Calculators
Everyday maths — percentages, dates, units. Every one runs in your browser: nothing is uploaded, and there is no account or queue.
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All 40 calculators
Work and payroll
Money
- Sales Tax & VAT Calculatoradd or back out taxAdd tax, or take it back out of a tax-inclusive price.
- Percentage Calculatorof, what percent, changeThree percentage questions, each with the sum written out.
- Currency Converterdaily rates, cached hereMid-market rates, dated, so you can see the spread you are charged.
- Compound Interest Calculatorsavings with monthly depositsWhat your savings grow to, with the year-by-year table.
- Loan Calculatorfixed or declining paymentsThe monthly payment and every month of the schedule.
- Tip Calculatorsplit between peopleTip, total and the split, without doing it at the table.
- Discount Calculatorprice after a percent offSale price, saving, and what you are really paying.
Dates and time
- Days Between Datesdays between two datesDays, weeks, months and working days between two dates.
- Date Calculatoradd or subtract daysA date plus or minus days, business days, months or years.
- Age Calculatorexact age todayExact age in years, months and days, plus the next birthday.
- Unix Timestamp Converterepoch to date and backEpoch time to a readable date, and back again.
Training and health
- BMI Calculatorwith the bandsBMI, its class, and where the weight actually sits.
- TDEE Calculatormaintenance and targetsCalories to maintain, and sensible targets either side.
- Macro Calculatorgrams and per mealProtein, carbs and fat in grams, a day and a meal.
- One Rep Max Calculatorthree formulas and a % tableYour max from a set you already did, and the % table.
- Body Fat Calculatorwith a tape measureBody fat from a tape measure, with fat and lean mass.
- Protein Calculatorwith food examplesGrams of protein a day, per meal, and on a plate.
- Plate Calculatorplates per side, drawnWhich plates go on each side, drawn on the bar.
- Warm-up Calculatorsets rounded to your platesFour sets up to your working weight, ready to load.
- Heart Rate Zone CalculatorTanaka and KarvonenFive zones in beats per minute, and what each is for.
- Pace Calculatorsplits and race predictionsPace, time or distance from the other two, with splits.
- Interval TimerTabata, EMOM and restRounds of work and rest, with beeps you can hear.
- Calories Burned Calculatorby activity, 2024 METsCalories for an activity, from its METs and your weight.
- FFMI Calculatorlean mass for your heightLean mass for your height, in one number.
- Water Intake Calculatorwith training and sweatThe day's water, plus what training takes out.
- Wilks and DOTS CalculatorDOTS and WilksYour total on a scale that levels body weight.
- Waist-to-Height Ratio Calculatorkeep it under 0.5Is your waist less than half your height?
- Supplement Calculatorwhey, gainer, creatine, pre-workoutHow much of each, a day, and when — for your weight and goal.
Everyday
Units
- Color ConverterHEX, RGB, HSL and contrastOne colour in every notation, with its contrast.
- Length Convertermetres, feet, milesMeters, feet, inches, miles — all of them at once.
- Weight Converterkg, pounds, ouncesKilograms, pounds, stone, and the three different tons.
- Temperature ConverterCelsius, Fahrenheit, KelvinCelsius, Fahrenheit and Kelvin, offsets included.
- Volume Converterlitres, gallons, cupsLiters, cups, pints and gallons, US and UK kept apart.
- Area Converterm², acres, hectaresSquare meters, square feet, acres and hectares.
- Speed Converterkm/h, mph, knotskm/h, mph, m/s and knots.
- Data Storage ConverterMB, GB, TB, bitsMB, GB, TB in both the 1000 and 1024 senses.
Calculators that show the working
Most online calculators give a number and nothing else, which is useless the moment you need to check it or explain it to somebody. The ones here show the arithmetic alongside the answer, and update as you type rather than waiting for a button.
They also run entirely in the browser, which for a calculator matters less for privacy than for speed: the answer appears as fast as you can change the input, because nothing is being sent anywhere.
The ones people get wrong
Removing tax from a gross figure is not the same as subtracting the tax rate. Taking 20% off a price that already includes 20% VAT means dividing by 1.2, not multiplying by 0.8 — a difference of about four percent, which is the single most common mistake in this category. The tax calculator here does both directions and names which one it is doing.
Percentage change is the other: a rise from 40 to 50 is a 25% increase, while a fall from 50 to 40 is a 20% decrease, and the two are not symmetrical even though the gap is the same. The percentage calculator writes the expression out so the direction is visible.