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Free Calculators & Unit Converters
28 toolsRuns in your browser
Everyday maths done for you: convert units, work out money, health and study numbers, and do date and time arithmetic.
Converters
- Length ConverterConvert cm to inches, feet to meters, miles to km and more.
- Weight ConverterConvert kg to pounds, ounces to grams, stone and more.
- Temperature ConverterConvert Celsius, Fahrenheit, Kelvin and Rankine.
- Volume ConverterConvert cups, mL, liters, gallons, fluid ounces and spoons.
- Speed ConverterConvert mph, km/h, m/s, knots and ft/s.
- Data Storage ConverterConvert bytes, KB, MB, GB, TB and the binary KiB, MiB, GiB.
- Roman Numeral ConverterConvert numbers to Roman numerals and back, from 1 to 3999.
Money Calculators
- Percentage CalculatorPercent of a number, percent change, increase and decrease, reverse percent.
- Tip CalculatorWork out the tip and split the bill between any number of people.
- Loan Payment CalculatorMonthly payment, total interest and yearly breakdown, with extra-payment savings.
- Compound Interest CalculatorSee how savings grow with compounding and monthly deposits.
- Discount CalculatorFind the sale price, savings, or percent off. Stack two discounts.
- Sales Tax CalculatorAdd sales tax / VAT to a price, or take it out of a total.
- Hourly to Salary CalculatorConvert hourly pay to annual salary, or salary to an hourly rate.
- Debt Payoff CalculatorCompare snowball and avalanche plans and see your debt-free date.
Health & Study Calculators
- GPA CalculatorSemester and cumulative GPA on the 4.0 scale, with honors/AP weighting.
- BMI CalculatorBody mass index, category and healthy weight range, metric or imperial.
- TDEE & Calorie CalculatorEstimate BMR and daily maintenance calories for weight loss or gain.
- Running Pace CalculatorWork out pace per km and mile, or the finish time for a pace.
- Final Grade CalculatorSee what score you need on your final exam to reach a target grade.
Date & Time Tools
- Age CalculatorExact age in years, months and days, plus days until your next birthday.
- Days Between Dates CalculatorDays, weeks and weekdays between two dates, or add/subtract days from a date.
- Add Days to Date CalculatorAdd or subtract days, weeks, months or years from any date.
- Working Days CalculatorCount Monday–Friday working days between two dates, minus holidays.
- Time Zone ConverterConvert a date and time between world time zones with DST handled.
- Pomodoro TimerA simple focus timer: 25-minute sessions with short and long breaks.
Everyday & Random
About these calculators
Each calculator on this page does one job and shows its working in the guide underneath the tool. The unit converters use the exact internationally agreed definitions (an inch is exactly 2.54 centimetres, a pound exactly 0.45359237 kilograms), so results do not drift when you convert back and forth. The money tools, such as the loan, compound interest, discount, sales tax and debt payoff calculators, use standard formulas and explain their assumptions, for example how often interest compounds or whether tax is added to the price or already inside it.
The health and study tools give estimates, not medical or academic advice. The date and time tools do calendar arithmetic in your browser, so there is no server involved. Everything is free and nothing you enter leaves your device.