All Free Online Calculators & Tools
134 free tools across health, finance, time, digital, and life. All instant, all free, no signup. CalcPool tools are built on documented, checked methodology — established formulas for math and finance tools, peer-reviewed research where a health or science claim needs it. Every tool works on any device and never sends your personal data anywhere. Browse all 134 tools below, featured and trending picks first, or jump directly to a category using the links at the bottom of this page.
Binary ↔ Decimal Converter
Easily convert numbers between binary (base 2) and decimal (base 10) systems. Perfect for programmers, students, and anyone learning how computers work.
Binary ↔ Hexadecimal Converter
Easily convert numbers between binary (base 2) and hexadecimal (base 16) systems. Essential for programmers, web developers, and computer science students.
Binary ↔ Octal Converter
Easily convert numbers between binary (base 2) and octal (base 8) systems. Useful for computing and digital electronics.
Burnout Risk Calculator
Answer 10 science-backed questions about your work, sleep, and stress to get your burnout risk score and a personalised recovery plan.
Calorie Deficit Calculator
Calculate your calorie deficit in three steps. Get your TDEE, daily calorie target, macro breakdown, and a week-by-week weight-loss projection that adjusts for the drop in metabolism as you lose weight.
Compound Interest Calculator
Calculate compound interest on any investment or savings. See your final balance, total interest earned, and year-by-year growth — with optional monthly contributions. The most powerful free money calculator online.
Cosmic Age Calculator
Discover your age in cosmic units — on every planet in the solar system, in light-years, and as a fraction of the universe's 13.8 billion year history.
Daily Hydration Schedule
Get a personalised hourly drinking schedule based on your weight, wake time, and activity level. Stop guessing about hydration. Get a science-backed hourly plan for today.
Days Until Calculator
Live countdown to any event — Eid, Christmas, birthdays, exams, holidays, Ramadan. Add multiple events and watch the days, hours, minutes, and seconds tick in real time.
Deadline Countdown Timer
A live countdown timer for any deadline — exams, project submissions, work presentations, personal goals. Set multiple deadlines and watch the clock tick in days, hours, minutes, and seconds.
Decimal ↔ Hexadecimal Converter
Easily convert numbers between decimal (base 10) and hexadecimal (base 16) systems. Essential for web developers working with colour codes and programmers debugging memory addresses.
Decimal ↔ Octal Converter
Easily convert numbers between decimal (base 10) and octal (base 8) systems. Useful for understanding Unix/Linux file permissions and legacy computing systems.
Discount Calculator
Free discount calculator with 4 modes: standard discount, stacked coupons, reverse (find original price or % off), and shopping cart with multiple items. Works in any currency with VAT support.
Electricity Bill Calculator
Find out exactly how much each appliance costs you per day, month, and year. Finally understand your electricity bill.
Exact Age Calculator
Your precise age in years, months, weeks, days, hours, minutes, and live seconds. Find what day of the week you were born, your next metric birthday (10,000 days, 1 billion seconds), a multi-year birthday-weekday forecast, and a downloadable age card.
Hexadecimal ↔ Octal Converter
Easily convert numbers between hexadecimal (base 16) and octal (base 8) systems. Useful for low-level programming, computing systems, and when working with different number representations.
Inflation Impact Calculator
Calculate the real impact of inflation on any amount of money over any time period. See how much purchasing power you have lost — and what you need to earn today to match what you earned before.
Life Progress Bar
See your entire life visualised as a grid of weeks, calculated from exact dates rather than a rough approximation. Adjust for your country's life expectancy or your own lifestyle, download a shareable poster, and see how many summers, Sundays, and birthdays remain — all calculated privately in your browser.
Loan EMI Calculator
Calculate your EMI for any home loan, car loan, or personal loan. See total interest, a full amortisation schedule, how a lump-sum prepayment can shorten your loan or lower your EMI, an EMI-to-income affordability check, and a side-by-side comparison against a second loan offer.
Margin Calculator
Calculate gross margin, net margin, and markup for any product or service. Compare against real industry benchmarks, analyse multiple products simultaneously, and find your break-even point. The most complete free margin calculator online.
Phone Life Thief Calculator
Calculate exactly how many days, weeks, and years of your life you have lost and will lose to your phone screen — based on your daily screen time.
Real Hourly Wage Calculator
Your salary looks good on paper. After tax, commute time, work prep, decompression, unpaid overtime, and job-related expenses — what is your real hourly rate? Enter your numbers and find out.
Salary to Daily Rate Calculator
Convert any annual, monthly, or weekly salary into a precise daily rate, hourly rate, and contractor equivalent — or work the other way, from a day rate to its salary equivalent. Simple, adjustable working-day settings.
Sleep Calculator
Calculate the best time to sleep or wake up based on 90-minute sleep cycles, an exact custom duration, or your own age group. Never wake up groggy again.
Test Grade Calculator
Calculate your test grade from any score. Supports US, UK, German, Pakistani, Indian, and Nigerian grading systems. Includes weighted grade calculator, reverse 'what score do I need?' tool, and a teacher class grader.
Tip Calculator & Bill Splitter
Calculate the perfect tip and split any restaurant bill between any number of people — equally or by custom amounts. Works in any currency worldwide with built-in tipping guides by country.
Today's Meal Timing Calculator
Get your personalised eating schedule based on your wake time and health goal. Science-backed circadian nutrition — the what matters far less than the when.
What If I Invested Calculator
See exactly how much money you would have today if you had invested your daily, weekly, or monthly spending — on coffee, subscriptions, eating out, or any habit — instead of spending it.
Net Worth Calculator
Free net worth calculator with fewer fields and a side-by-side layout that fits on one screen. Enter your assets and liabilities to instantly see your net worth, liquid net worth, and debt-to-asset ratio — calculated entirely in your browser.
Acceleration Calculator
Calculate acceleration from a change in velocity over time (a = Δv ÷ t), or solve for final velocity, initial velocity, or time using v = u + a·t. Includes the displacement too.
Add or Subtract Days Calculator
Add or subtract any number of days from a date to find the resulting day — useful for deadlines, contract notice periods, pregnancy and project dates, and '90 days from today' questions.
Age Gap Calculator
Find the precise age difference between two people from their birth dates — in years, months, and days, plus the total days apart.
Age in Units Calculator
Enter your date of birth to see your exact age in years, months, and days, plus the total number of days, weeks, hours, minutes, and seconds you've been alive.
Alcohol Units Calculator
Work out how many alcohol units are in your drinks. Enter the drink type and number, and get UK units, grams of pure alcohol, and US standard drinks for beer, wine, and spirits.
Area Calculator
Calculate the area of a rectangle, circle, triangle, or trapezoid. Enter dimensions in feet, metres, inches, or yards and get the area, plus the equivalent in square feet.
Attendance Percentage Calculator
Calculate your attendance percentage from classes attended and held, then see how many more classes you can safely miss, or must attend, to hit a target like 75%.
Average Calculator
Paste any list of numbers and instantly get the mean (average), median, mode, minimum, maximum, range, count, sum, and both sample and population standard deviation. Handles decimals and negatives.
BMI Calculator
Calculate your Body Mass Index (BMI) from your height and weight in metric or imperial units, see your WHO weight category, and find the healthy weight range for your height.
BMR Calculator
Calculate your basal metabolic rate (BMR) — the calories your body burns at complete rest — using the Mifflin-St Jeor and Harris-Benedict equations, with daily calorie estimates for different activity levels.
Board Foot Calculator
Calculate board feet from thickness, width, and length, for one piece or a batch. Add a price per board foot to estimate the total lumber cost.
Body Fat Calculator
Estimate your body fat percentage from simple tape measurements using the US Navy method. Enter height, neck, and waist (plus hip for women) to get body fat and lean mass.
Brick Calculator
Estimate how many bricks you need for a wall. Enter the wall dimensions or a known area, pick the brick type, and get a brick count including a waste allowance.
Business Days Calculator
Count the number of business days (Monday to Friday) between two dates, excluding weekends. Ideal for working deadlines, delivery estimates, and project timelines measured in working days.
Caffeine Calculator
Track your daily caffeine intake from coffee, tea, cola, energy drinks and more, and see how it compares with the general safe limit. Estimates when caffeine clears your system.
Calories Burned Calculator
Estimate how many calories you burn during exercise using MET values. Pick an activity, enter your body weight and duration, and get calories burned plus the rate per minute and hour.
Case Converter
Convert pasted text to sentence, title, upper, or lower case, or turn words into camelCase, snake_case, kebab-case, and other programming identifier styles.
CGPA to Percentage Calculator
Convert CGPA to a percentage (and percentage to CGPA) using the CBSE × 9.5 rule, a generic 10-point scale, or the US 4.0 scale. Clearly labelled, because the right formula depends on your institution.
Character Counter
Count user-perceived characters, words, lines, and UTF-8 bytes. See GSM-7 or Unicode SMS segments and compare your draft with common platform length guidance.
Click Speed Test
Choose a short test duration, click the button while the timer runs, and review your average clicks per second. Counts are measured in this page only.
Color Converter
Convert any colour between HEX, RGB, and HSL instantly. Type a hex code or adjust the red, green, and blue sliders to see the colour and all three formats update live.
Concrete Calculator
Estimate how much concrete you need for a slab, footing, or round column. Enter your dimensions in feet and inches and get cubic yards, cubic metres, and the number of 60 lb or 80 lb bags — including a waste allowance.
Cooking Measurement Converter
Convert cooking measurements between cups, tablespoons, teaspoons, millilitres, grams, and ounces — adjusted for the ingredient, since flour, sugar, and butter all weigh differently.
Cost Per Use Calculator
Divide the true cost of an item — price plus any running or maintenance cost, minus resale value — by how many times you'll use it, to reveal its real cost per use.
Data Storage Converter
Convert between bytes, kilobytes, megabytes, gigabytes, and terabytes — showing both the decimal (1 KB = 1,000 bytes) and binary (1 KiB = 1,024 bytes) values, so you can see why a '1 TB' drive reports as ~931 GiB.
Date Difference Calculator
Find the difference between any two dates in years, months, weeks, days, and hours. Handles leap years exactly — perfect for calculating durations, project timelines, and time between events.
Density Calculator
Calculate density from mass and volume, or find mass or volume from density. Handles grams, kilograms, pounds, litres, millilitres, cubic metres and more, reporting in both g/cm³ and kg/m³.
Download Time Calculator
Estimate how long a file takes to download from its size and your internet speed. Accounts for the bits-vs-bytes difference that trips up most estimates.
Drywall Calculator
Estimate drywall sheets for a room. Enter the dimensions, choose whether to include the ceiling, deduct doors and windows, and get the sheet count with a waste allowance.
Energy Calculator
Calculate kinetic energy (½mv²), gravitational potential energy (mgh), and work done (F × d) in joules, with results also in kilojoules and calories.
Escape Velocity Calculator
Calculate the escape velocity of Earth, the Moon, Mars, Jupiter, the Sun, or any custom body from its mass and radius. See the result in km/s, km/h, and Mach.
Exponent Calculator
Calculate a base raised to any exponent — positive, negative, or fractional. See the expanded multiplication for whole-number powers, and handle roots via fractional exponents.
Final Grade Calculator
Find out exactly what you need to score on your final exam to reach the overall grade you want, based on your current grade and how much the final is worth.
Force Calculator
Calculate force from mass and acceleration with Newton's second law, or find the mass or acceleration from force. Switch acceleration to gravity to get an object's weight in newtons.
Fraction Calculator
Add, subtract, multiply, or divide two fractions and get the answer fully simplified, as a decimal, and as a mixed number. Shows exact whole-number results via the greatest common divisor.
Fuel Cost Calculator
Estimate the fuel cost of a journey from the trip distance, your vehicle's fuel efficiency, and the price of fuel. Works in km or miles, and in L/100km, MPG, or km/L.
Generation Calculator
Find out which generation a birth year falls into — from the Silent Generation and Baby Boomers to Gen X, Millennials, Gen Z, Gen Alpha, and Gen Beta — with the full range for each.
GPA Calculator
Calculate your GPA on the standard 4.0 scale by entering each course's letter grade and credit hours. The calculator weights every course by its credits for an accurate grade point average.
Gravel Calculator
Calculate how much gravel, sand, topsoil, or mulch you need. Enter your area and depth to get the volume in cubic yards and the weight in tons and pounds.
Habit Cost Calculator
Turn a small daily, weekly, or monthly spend into its true long-term cost — per month, per year, and over 5 and 10 years. See what that coffee, subscription, or takeaway adds up to.
Hash Generator
Generate SHA-256, SHA-384, or SHA-512 digests for a text input using the browser's Web Crypto API. SHA-1 is offered only for legacy compatibility comparisons.
Heart Rate Zone Calculator
Calculate your five heart rate training zones using the Karvonen method or a percentage of maximum heart rate. Enter your age and resting heart rate to get bpm ranges for recovery through to maximum effort.
Ideal Gas Law Calculator
Solve the ideal gas law PV = nRT for pressure, volume, amount, or temperature. Enter the other three with flexible units (atm, kPa, bar; L, mL, m³; K, °C, °F) and get the answer in SI and everyday units.
Ideal Weight Calculator
Estimate your ideal body weight using the Robinson, Miller, Devine, and Hamwi formulas, alongside the healthy weight range from BMI. Based on your height and sex.
Image Compressor
Compress a local image to a best-effort target size by adjusting JPEG quality. Preview the result and download it without uploading the original.
Image Converter
Convert JPEG, PNG, or WebP images to another browser-supported format. Preview and download the converted copy without sending the source file to a server.
Image Resizer
Enter a width and height in pixels, preview the resized image, and export it as WebP, JPEG, or PNG directly from your browser.
Intermittent Fasting Calculator
Plan your intermittent fasting schedule. Pick a method like 16:8, 18:6, or 20:4, set when your eating window starts, and get your exact eating and fasting times.
JSON Formatter
Parse JSON to catch syntax errors, then format valid data with consistent indentation. Your pasted content is handled in this browser tab.
JWT Decoder
Decode the Base64URL-encoded header and payload of a JSON Web Token for debugging. This local inspection does not verify its signature or make the token safe to share.
LCM & GCD Calculator
Find the LCM (lowest common multiple) and GCD / HCF (greatest common divisor) of two or more whole numbers instantly, using the Euclidean method.
Light Travel Time Calculator
Calculate how long light takes to travel across any distance — from the Earth-Moon gap to interstellar space. Enter kilometres, AU, light-years, or parsecs and get the travel time.
Macro Calculator
Convert a daily calorie target into grams of protein, carbohydrate, and fat for popular diet splits — balanced, low-carb, high-carb, keto, and high-protein.
Microphone Test
Request microphone permission when you start, then speak to see a local audio-level meter respond. The tool does not record or transmit audio.
Molar Mass Calculator
Type any chemical formula — including brackets like Ca(OH)2 — and get its molar mass in g/mol, a full element-by-element breakdown, and each element's mass percentage.
Ohm's Law Calculator
Solve Ohm's Law instantly — enter any two of voltage, current, and resistance and get the third, plus the power dissipated. Works in volts, amps, ohms, and watts.
One Rep Max Calculator
Estimate your one-rep max (1RM) from a set you've already done. Enter the weight and reps, and get the 1RM plus a percentage table for planning working sets.
Orbital Period Calculator
Calculate the orbital period of a planet, moon, or satellite using Kepler's third law. Enter a distance from the Sun in AU, or a custom central mass and orbit radius.
Ovulation Calculator
Estimate your ovulation day and fertile window from your last period and cycle length. Shows your most fertile days and when your next period is expected.
Paint Calculator
Estimate how many litres or gallons of paint a room needs. Enter the dimensions, subtract doors and windows, choose your number of coats, and get a realistic amount — including the ceiling if you want it.
Password Generator
Choose a length and character groups to generate a random password using the browser's cryptographically secure random-number generator. Passwords are not stored by CalcPool.
Percentage Calculator
A free percentage calculator that answers the three questions people actually ask: what is X% of a number, what percent one number is of another, and the percentage increase or decrease between two values. The formula is shown with every result.
Pet Age Calculator
Convert your dog's or cat's age into human years with a realistic formula that accounts for the fast early years and breed size — not the outdated 'multiply by 7' rule.
pH Calculator
Convert between pH, pOH and hydrogen ion concentration [H⁺]. Enter any one value and get the rest, with an instant acid/neutral/base reading.
Pregnancy Due Date Calculator
Estimate your pregnancy due date from your last menstrual period or conception date, with your current gestational age in weeks and days and your trimester. Uses Naegele's rule.
Pressure Calculator
Calculate pressure from force and area, or solve for force or area. Enter area in m², cm², in² and more, and read pressure in pascals, kPa, bar, atm, and psi.
Protein Intake Calculator
Calculate your daily protein target in grams based on your body weight and goal — general health, muscle building, fat loss, or endurance training. Shows the range and calorie contribution.
QR Code Generator
Create a downloadable QR image for text, a URL, Wi-Fi, email, phone, or SMS. QR content is encoded locally in your browser.
Race Time Predictor
Use the Riegel formula to predict your race time at 5K, 10K, half marathon, or marathon from a recent result. Shows your predicted pace so you can plan a realistic target.
Random Number Generator
Generate one or many random whole numbers between any minimum and maximum, with an option for no duplicates. Great for draws, giveaways, games, sampling, and decision-making.
Ratio Calculator
Reduce any ratio to its simplest form (two or three terms), see it as a decimal and a '1 : n' scale, and solve proportions like 3 : 4 = 9 : ? by leaving one value blank. Handles decimals too.
Reaction Time Test
Wait for the green signal and click as quickly as you can. The browser reports the elapsed time while noting that display and input latency influence results.
Reading Time Calculator
Estimate how long a piece of text takes to read from its word count, at slow, average, or fast reading speeds — and compare the same text at each speed.
Recipe Scaler
Scale a recipe to any number of servings. Enter the original and new serving counts, list your ingredients, and get every amount recalculated instantly.
Rent Split Calculator
Split rent between housemates equally, or proportionally by each person's income so everyone pays a fair share. Add as many people as you need.
Roof Pitch Calculator
Convert a roof's rise and run into pitch (x:12), degrees, and percentage slope. Enter your footprint to get the true roof area using the slope-factor multiplier.
Rounding Calculator
Round any number to a set number of decimal places (with round-up and round-down shown), to significant figures, or to the nearest 10, 100, 1000 or any multiple.
Running Pace Calculator
Calculate your running pace from a time and distance — in minutes per km and per mile — or predict the time for a new distance at a given pace. Handles 5K, 10K, half marathon and marathon.
Savings Goal Calculator
Enter a savings goal, what you've saved already, and a monthly amount to see how many months (and what date) you'll hit the target — with optional interest factored in.
Scientific Notation Converter
Convert any number to scientific notation (a × 10ⁿ) and E-notation, or expand scientific notation back to a plain decimal. Works both directions, for very large and very small numbers.
Speech Time Calculator
Estimate how long a speech, script, or presentation takes to deliver from its word count, at slow, conversational, or fast speaking paces. Perfect for timing a talk or a timed exam answer.
Spin the Wheel
Enter names or choices on separate lines and let the browser select one at random. Each non-empty line is one entry, so repeated choices have proportionally greater chance.
Square Root Calculator
Find the square root, cube root, or any nth root of a number. Handles decimals and negative numbers (for odd roots), and shows a check so you can see the result is right.
Steps to Distance Calculator
Turn a step count into a distance. Enter your steps and height (or your own stride length) to see how far you've walked in kilometres and miles, plus an approximate calorie figure.
Study Planner Calculator
Enter how long you need to study and this planner builds a Pomodoro-style schedule of focus sessions and breaks, with the total time and finish time worked out.
Swim Pace Calculator
Calculate your swimming pace per 100 metres and per 100 yards from a distance and time. Also shows laps for your pool length and speed in km/h.
Target Heart Rate Calculator
Find the heart rate to aim for at a chosen exercise intensity, using the Karvonen method or a percentage of maximum heart rate. Adjust the intensity slider from easy to maximal effort.
TDEE Calculator
Calculate your total daily energy expenditure (TDEE) — how many calories you burn each day including activity — from your age, sex, height, weight, and activity level. Shows maintenance, weight-loss, and weight-gain targets.
Telescope Magnification Calculator
Calculate telescope magnification from the telescope and eyepiece focal lengths, including Barlow lenses. Also shows exit pupil, focal ratio, and the useful magnification limits for your aperture.
Tile Calculator
Estimate how many tiles and boxes you need for a floor or wall. Enter the area and tile size, add a waste allowance, and get the tile count and boxes to buy.
Time Duration Calculator
Find the time between any two clock times — shift length, meeting duration, or elapsed time — in hours and minutes, with an optional break subtracted. Handles overnight spans.
Timesheet Calculator
Enter start time, end time, and unpaid breaks for each day and get your total working hours — in hours and minutes and as decimal hours for payroll.
Typing Speed Test
Type a sample passage for up to one minute and see an approximate words-per-minute score and accuracy. Results are for practice, not formal assessment.
Unit Price Calculator
Compare two products by their unit price — the cost per gram, millilitre, or item — to see which is genuinely the better value, regardless of pack size or price tag.
VO2 Max Calculator
Estimate your VO2 max — a key measure of cardiovascular fitness — from your resting and maximum heart rate, with a fitness rating for your age and sex.
Volume Calculator
Calculate the volume of a box, cylinder, sphere, or cone. Enter dimensions in feet, metres, inches, or yards and get the volume in cubic units, litres, and gallons.
Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio and see your WHO health-risk category. A simple screening measure of how body fat is distributed, which matters more than weight alone.
Water Intake Calculator
Estimate your daily water target in litres and cups from your body weight, exercise time, and climate. A practical guide for staying properly hydrated.
Wavelength Calculator
Convert between wavelength and frequency using c = λf, with photon energy in joules and electronvolts. Enter a wavelength (in nm, µm, or m) or a frequency (Hz to THz).
Webcam Test
Request camera permission when you start and display a local muted preview. Stop the test to turn off the camera stream.
Week Number Calculator
Find the ISO week number for any date, plus the day of the year, the quarter, the weekday, and how many weeks are left in the year.
Weight on Other Planets Calculator
Find out what you'd weigh on the Moon, Mars, Jupiter, and every planet in the Solar System. Enter your Earth weight and see it scaled by each world's surface gravity.
Weighted Grade Calculator
Calculate your overall course grade from weighted categories — homework, quizzes, midterms, finals — each with its own score and weight. The calculator weights every category correctly and handles weights that don't sum to 100.
Word Counter
Count words, sentences, paragraphs, and unique terms in a draft. Estimate reading and speaking time, set a word goal, and inspect frequent words while your text stays in the browser.
Words to Pages Calculator
Convert a word count into an estimated page count, and compare it across common formats — single-spaced, double-spaced, and large-print. Ideal for essays, reports, and assignments with a page limit.
All Calculators are 100% free • No registration required • Instant results
Browse All Tools by Category
12 categories — find exactly what you need
Health & Wellness
Free health calculators for BMI, sleep cycles, hydration,...
10 tools
Education & Learning
Free calculators for students and teachers — grades, test...
10 tools
Finance & Money
Free financial calculators for loans, compound interest, ...
11 tools
Time & Date
Free time calculators for age, countdowns, deadlines, dat...
10 tools
Math & Statistics
Free calculators for percentages, averages, ratios, fract...
10 tools
Science
Free calculators for physics, chemistry, and scientific p...
10 tools
Engineering & Construction
Free calculators for area, volume, materials, concrete, a...
10 tools
Food & Nutrition
Free nutrition calculators for meal timing, calories, mac...
10 tools
Digital & Technology
Private browser utilities for number systems, QR codes, s...
12 tools
Sports & Fitness
Free fitness calculators for training, performance, pace,...
10 tools
Everyday Life
Free tools for daily habits, productivity, life planning,...
11 tools
Space & Universe
Free cosmic calculators for your age on other planets, li...
6 tools
Text & Writing Tools
Browser-based text utilities for word counts, character l...
3 tools
Image Tools
Resize, compress, and convert images locally in your brow...
3 tools
Developer Tools
Local JSON, digest, and token inspection utilities for de...
3 tools
Online Tests
Interactive typing, click, reaction, microphone, and webc...
5 tools
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