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Converters

Length Converter Enter a length in any unit to see it converted to metric and imperial units at once.

Temperature Converter Enter a temperature in any unit to see the equivalent in Celsius, Fahrenheit and Kelvin at the same time.

Weight & Mass Converter Enter a weight in any unit to see it in metric and imperial units at once.

Volume Converter Enter a volume in any unit to see metric, US and imperial equivalents at once.

Speed Converter Enter a speed in any unit to see it in every other unit at once.

Area Converter Enter an area in any unit to see metric and imperial equivalents at once.

Data Storage Converter Convert digital storage and bandwidth units, including both decimal (KB) and binary (KiB) prefixes.

Time Unit Converter Convert durations between time units, from nanoseconds to years.

Pressure Converter Enter a pressure in any unit to see it in every other unit at once.

Energy Converter Enter an amount of energy in any unit to see it in every other unit at once.

Fuel Economy Converter Convert fuel economy between L/100 km, km/L, US MPG and UK MPG, with the inverse maths handled for you.

Cooking Temperature Converter Convert oven temperatures between Celsius, Fahrenheit and gas mark, with the fan-oven setting.

Aspect Ratio Calculator Simplify dimensions into an aspect ratio, and find a missing dimension for a target ratio.

Power Converter Enter a power value in any unit to see it in every other unit at once.

CSS Unit Converter Convert CSS lengths between px, em, rem, pt and percent using a configurable base font size.

DPI / PPI Calculator Calculate a screen's pixels per inch from its resolution and diagonal size, with dot pitch.

Force Converter Enter a force in any unit to see it in every other unit at once.

Download Time Calculator Estimate transfer time from a file size and connection speed, handling megabits and megabytes.

Angle Converter Enter an angle in any unit to see it in every other unit at once.

Roman Numeral Date Converter Convert a date into Roman numerals for the day, month and year, as used on monuments and clocks.

Frequency Converter Enter a frequency in any unit to see it in every other unit at once.

Math Tools

Percentage Calculator Three percentage calculators in one — find a percentage of a number, a ratio as a percentage, and percentage change.

Prime Number Checker Test any whole number for primality and, if it is composite, see its prime factors.

Average Calculator Calculate the mean, median, mode, range, sum and count of any list of numbers.

Fraction Calculator Enter two fractions and an operation to get a simplified result, with decimal and mixed-number forms.

GCD & LCM Calculator Enter a list of whole numbers to get their GCD and LCM at once.

Quadratic Equation Solver Enter the coefficients a, b and c to find the roots, discriminant and vertex of a quadratic equation.

Roman Numeral Converter Type a number to get its Roman numeral, or type a numeral to get the number — both directions update live.

Ratio Calculator Enter a ratio to simplify it, see it as a decimal, and scale it so the first term equals any number.

Circle Calculator Enter any one circle measurement — radius, diameter, circumference or area — to get all the others.

Triangle Calculator Enter the three side lengths to get area, perimeter, all three angles and the triangle's type.

Scientific Notation Converter Enter a number in any form to see its scientific, engineering, E-notation and decimal equivalents.

Factorial Calculator Calculate the exact factorial of any whole number up to 5000, with the full number of digits.

Modulo Calculator Find a mod n with the quotient, the programming remainder and the true mathematical modulo.

Logarithm Calculator Calculate a logarithm in any base, plus natural (ln), common (log₁₀) and binary (log₂) logs.

Significant Figures Calculator Round a number to a set number of significant figures, and count the sig figs in any value.

Number to Words Convert any number into written words, handling negatives and decimals, in your page language.

Finance Calculators

Tip Calculator Enter the bill, choose a tip percentage and split it — see the tip, total and amount per person instantly.

Discount Calculator Enter a price and a percentage off to see the final price and the amount you save.

Sales Tax Calculator Add sales tax to a net price, or extract the net amount and tax from a tax-inclusive total.

Compound Interest Calculator Project the future value of savings or investments with compound interest and optional regular deposits.

Simple Interest Calculator Enter a principal, rate and time to calculate the simple interest and final total.

Mortgage Amortization Calculator Calculate your monthly mortgage payment and a full amortization schedule of principal and interest.

Loan & Mortgage Calculator Enter a loan amount, interest rate and term to see the monthly payment and the total interest you'll pay.

Savings Goal Calculator Work out how long until you hit a savings goal, or the monthly contribution needed to reach it in time.

Credit Card Payoff Calculator Find how long to clear a credit card balance at a fixed payment, and the total interest you'll pay.

Salary Converter Convert a pay rate between hourly, daily, weekly, monthly and yearly using your own work schedule.

Break-Even Calculator Calculate the units and revenue you need to break even from fixed costs, price and variable cost.

Markup and Margin Calculator Work out price, profit, markup and margin from a cost plus a price, a markup or a target margin.

Inflation Calculator Project how a steady inflation rate changes the future cost and purchasing power of an amount.

ROI Calculator Enter an amount invested and its final value to get net profit, total ROI and annualized ROI.

Retirement Calculator Project your retirement nest egg from current savings, monthly contributions, return and time.

CAGR Calculator Calculate the compound annual growth rate from a beginning value, ending value and number of years.

Date & Time Tools

Age Calculator Enter a date of birth to get the exact age in years, months and days, with totals in days and weeks.

Date Difference Calculator Pick two dates to see the number of days, weeks, and the full years-months-days breakdown between them.

Business Days Calculator Count working days between two dates, skipping weekends and any holidays you list.

Countdown Timer Set a duration and count down to zero, with start, pause and reset controls.

Date Add and Subtract Add or subtract years, months, weeks and days from a date to find the resulting date.

Online Stopwatch Time anything to the centisecond, record laps, and pause or reset whenever you need.

Week Number Calculator Find the ISO 8601 week number for any date, plus its week-year and weeks in the year.

Day of the Week Calculator Find the weekday for any date, with its ISO weekday number and day of the year.

Leap Year Checker Check if a year is a leap year, with days in the year, February's length and upcoming leap years.

Time Zone Converter Convert a date and time between any two time zones, with correct daylight saving and UTC offsets.

Time Duration Calculator Find the duration between two clock times in hours and minutes, decimal hours and total minutes.

Hours Calculator Calculate worked hours between two times, minus a break, with optional pay at an hourly rate.

Sleep Calculator Get bedtimes or wake-up times aligned to 90-minute sleep cycles so you wake refreshed.

Pomodoro Timer Work in focused sessions with short and long breaks using a customisable Pomodoro timer.

Due Date Calculator Estimate a pregnancy due date from the last menstrual period, with gestational age and trimester.

Countdown to Event Count down the days, hours, minutes and seconds to any date and time, updating live.

Health Calculators

BMI Calculator Enter your height and weight to get your BMI, the WHO weight category, and the healthy weight range for your height.

BMR Calculator Enter your sex, weight, height and age to estimate the calories your body needs at complete rest.

TDEE Calculator Enter your details and activity level to estimate how many calories you burn in a day.

Body Fat Calculator Enter a few body measurements to estimate your body fat percentage with the U.S. Navy method.

Ideal Weight Calculator Enter your height and sex to see ideal weight estimates from four well-known formulas.

Calories Burned Calculator Estimate calories burned during exercise from the activity, your body weight and the duration.

Macronutrient Calculator Turn a daily calorie target into grams of carbs, protein and fat using a chosen macro split.

Running Pace Calculator Enter a distance and a time to calculate your pace per unit and your speed per hour.

One Rep Max Calculator Enter a weight and the reps you completed to estimate your one-rep max and training loads.

Water Intake Calculator Estimate your daily water intake from your body weight and exercise, in litres and cups.

Heart Rate Zone Calculator Calculate your max heart rate and five training zones from your age, optionally using resting HR.

Waist-to-Hip Ratio Calculator Calculate your waist-to-hip ratio and its WHO health-risk band, based on your sex.

Blood Alcohol Calculator Estimate blood alcohol concentration from weight, sex, standard drinks and time — for education only.

Text Tools

Word Counter Paste your text to see live word, character, sentence and paragraph counts — plus an estimated reading time.

Case Converter Paste text and instantly see it in every common letter case, each with a one-click copy button.

Slug Generator Convert a title into a lowercase, hyphenated URL slug, with a choice of separator.

Word Frequency Counter Paste text to rank the most common words with their counts and share of the total.

Text Diff Checker Compare two texts line by line and see added and removed lines highlighted, with a change count.

Title Case Converter Convert text to title case with smart handling of minor words, ideal for headlines and titles.

Remove Extra Spaces Paste text to collapse repeated spaces, trim each line and remove extra blank lines.

Text Reverser Flip your text backwards by characters, reverse the order of words, or reverse the order of lines.

Find and Replace Text Paste text, set a search and replacement, and swap every match — with case, whole-word and regex options.

Sort Lines Alphabetically Paste a list and sort the lines A→Z, Z→A or numerically, with optional case sensitivity.

Remove Duplicate Lines Paste a list to remove repeated lines, keeping the first of each, with a count of how many were removed.

Text Repeater Type a word or phrase, set how many times to repeat it and choose a separator.

Lorem Ipsum Generator Create classic Lorem Ipsum filler text — choose how many paragraphs, sentences or words you need.

Morse Code Translator Convert between plain text and international Morse code in either direction, instantly.

Caesar Cipher Shift letters to encode or decode a Caesar cipher, with any shift from 1 to 25 including ROT13.

Binary to Text Converter Convert text to 8-bit binary and decode binary back to text, with full UTF-8 support.

NATO Phonetic Alphabet Converter Convert text into the NATO phonetic alphabet so it can be spelled out clearly over phone or radio.

Palindrome Checker Check whether text is a palindrome, ignoring spaces, punctuation and letter case.

Developer Tools

Number Base Converter Enter a value and its base to see it in binary, octal, decimal and hexadecimal at once.

Color Converter Enter a colour as HEX, RGB or HSL and see the other formats update instantly, with a live swatch.

JSON Formatter & Validator Paste JSON to pretty-print it with indentation, minify it to one line, or check that it's valid.

Hash Generator Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text, computed locally in your browser.

Unix Timestamp Converter Convert between Unix epoch seconds and readable dates, in both directions, with UTC and ISO output.

Regex Tester Test a regular expression against text and see all matches, capture groups and positions live.

Base64 Encode & Decode Convert text to and from Base64. Handles Unicode correctly and never sends your data anywhere.

JWT Decoder Paste a JWT to read its decoded header and payload, with issued-at and expiry times.

HTML Entity Encoder / Decoder Convert text to HTML entities and back, handling reserved characters and numeric entities.

URL Encode & Decode Convert text to and from URL percent-encoding, handling spaces, symbols and Unicode.

Color Contrast Checker Check the WCAG contrast ratio between two colors, with AA and AAA results for normal and large text.

UUID Generator Create random version-4 UUIDs locally, with a choice of how many and one-click copy.

Bitwise Calculator Compute bitwise AND, OR, XOR and shifts on two integers, with decimal, hex and binary output.

CIDR Subnet Calculator Enter an IPv4 CIDR block to get the network, broadcast, mask, host range and usable host count.

Cron Expression Explainer Translate a 5-field cron expression into a plain-English description of when it runs.

HMAC Generator Generate an HMAC from a message and secret key with SHA-1, SHA-256, SHA-384 or SHA-512.

Random & Generators

Password Generator Create secure random passwords with your choice of length and character types, generated locally in your browser.

Random Number Generator Generate one or many random integers in a range you choose, with an option for unique (no-repeat) results.

Dice Roller Roll any combination of dice with an optional modifier, using fair, unbiased randomness.

Random Picker Pick one or more random winners from a list of entries, with fair, unbiased draws.

Coin Flip Flip one coin or thousands at once and see the running heads and tails tally.

Random Team Generator Split a list of names into random, balanced teams of nearly equal size in one click.

List Randomizer Paste a list, one item per line, and shuffle it into a fair random order.

Random Color Generator Generate a random colour and copy its HEX, RGB and HSL values for design and CSS work.

Lottery Number Generator Generate fair, unique lottery numbers for popular games or any custom pick-and-range.

Random Date Generator Generate a random date between two dates you choose, useful for test data and prompts.

Yes or No Generator Get a random yes or no answer, with an optional "maybe", whenever you can't decide.

statistics

Descriptive Statistics Calculator Paste a list of numbers to get the count, sum, mean, median, mode, range, variance and standard deviation.

T-Test Calculator Enter your data to compute a t-test — one-sample, independent two-sample (Welch) or paired — with the t value, df and p-value.

Percentile Calculator Find the value at any percentile in your data, with quartiles and the interquartile range.

Z-Score Calculator Convert a value into a z-score and find its percentile and the probability of scoring above it.

Permutations & Combinations Calculator Enter n and r to get the number of permutations, combinations and the factorial of n.

Weighted Average Calculator Calculate a weighted average from values and their weights, with the simple average for comparison.

Confidence Interval Calculator Calculate a confidence interval for a mean, with the margin of error and z critical value.

Correlation Coefficient Calculator Paste paired x, y data to get Pearson's r, R², and a plain-language read on the strength and direction.

Linear Regression Calculator Paste x, y data to find the best-fit line y = mx + b, its R², and predicted values for any x.

Probability Calculator Combine independent event probabilities and find the chance of at least one success over trials.

Sample Size Calculator Calculate the survey sample size needed from confidence level, margin of error and proportion.

Coefficient of Variation Calculator Calculate the coefficient of variation of your data, for sample and population, with mean and std dev.

Everyday Tools

GPA Calculator Add your courses with their letter grade and credits to get your weighted GPA on a 4.0 scale.

Final Grade Calculator Enter your current grade, your goal and the final's weight to see the score you need on the final exam.

Unit Price Calculator Enter the price and quantity of each option to see the cost per unit and which is the best value.

Fuel Cost Calculator Enter your trip distance, fuel economy and fuel price to see the fuel needed and the total cost.

Electricity Cost Calculator Enter an appliance's power, daily use, your price per kWh and a number of days to see the energy and cost.

Speed, Distance & Time Calculator Choose what to solve for and enter the other two values to get speed, distance or time.

Paint Calculator Estimate the litres of paint a room needs from its size, coats and coverage, minus openings.

Tile Calculator Find how many tiles and boxes you need for an area, including a waste allowance for cuts.

Concrete Calculator Calculate concrete volume for a slab in m³ and yd³, plus the number of pre-mix bags required.

Recipe Scaler Scale a recipe's ingredient quantities up or down by servings, with tidy fractions in the result.

Pizza Comparison Calculator Compare pizza deals by price per unit of area to find which one is genuinely the best value.

Gravel Calculator Calculate the volume and weight of gravel for an area and depth, in cubic metres and tonnes.