All calculators
Free calculators for money, health, maths, business and daily life — with the rules of your own country built in.
Saving & investing
Compound interest, savings goals, returns, inflation and retirement.
- Compound interest calculatorSee what savings grow to with regular contributions, compounding, and the tax your country applies to the gains.
- Simple interest calculatorCalculate simple interest on a principal over any period in years, months or days, with no compounding.
- Retirement calculatorProject the capital you will have at your country's pension age and the monthly income it can pay.
- Inflation calculatorSee what an amount will need to be in the future to keep the same purchasing power, and what money loses to inflation.
- Savings goal calculatorWork out how much to set aside each month to reach a savings target by a chosen date, with interest.
- ROI calculatorCalculate return on investment and the annualised rate, so investments of different lengths can be compared fairly.
- Net worth calculatorAdd up what you own and subtract what you owe, with liquid wealth and property equity shown separately.
Borrowing
Mortgages, credit cards and what a lender will let you borrow.
- Mortgage calculatorWork out the monthly payment, the total interest and the outstanding balance of a fixed-rate mortgage or loan.
- Credit card payoff calculatorSee how long a credit card balance takes to clear, what the interest costs, and what paying only the minimum would cost instead.
- Borrowing capacity calculatorEstimate how much you can borrow from your income, existing debts and a lender's debt-to-income limit.
- Car loan calculatorWork out the monthly payment, total interest and real cost of car finance, with deposit, trade-in and sales tax.
- Debt-to-income ratio calculatorCalculate your front-end and back-end debt-to-income ratios, the figures lenders use to decide how much you can borrow.
Business
Pricing, margin, tax and the point where a product pays for itself.
- VAT calculatorAdd or remove VAT, GST or sales tax at your country's standard rate, with the net, tax and gross amounts.
- Profit margin calculatorCalculate gross margin and markup from cost and selling price, and the profit across a batch of units.
- Break-even calculatorFind how many units you must sell to cover fixed costs, and what revenue that represents.
- Discount calculatorWork out a sale price, the amount saved, and the true combined rate when two discounts are applied one after another.
- Freelance hourly rate calculatorWork out the hourly rate a freelancer needs to charge, counting unbillable time, business costs, holidays and tax.
- Advertising metrics calculatorCalculate CTR, CPC, CPM, conversion rate, CPA and ROAS from one set of campaign figures, with break-even ROAS.
- Sales commission calculatorCalculate sales commission with a base salary, a quota and an accelerated rate above it, plus the effective rate.
Health
Body measurements and cycle dates, with clear limits on what they mean.
- BMI calculatorCalculate body mass index in metric or imperial units, with the WHO category and the matching weight range.
- BMR and TDEE calculatorEstimate basal metabolic rate with the Mifflin–St Jeor equation and daily energy use from your activity level.
- Body fat calculatorEstimate body fat percentage with the US Navy tape method, plus fat mass, lean mass and waist-to-height ratio.
- Water intake calculatorEstimate how much water to drink a day from your weight, exercise and climate, separating drinks from fluid in food.
- Heart rate zone calculatorCalculate your maximum heart rate and the five training zones, by the Karvonen reserve method or as a percentage of maximum.
- Running pace calculatorCalculate pace, time or distance for a run, with equivalent race times for 5k, 10k, half marathon and marathon.
- Ideal weight calculatorCompare ideal body weight by the Devine, Robinson, Miller and Hamwi formulas against the healthy BMI range for your height.
- One-rep max calculatorEstimate your one-repetition maximum from a set near failure, by the Epley, Brzycki and Lombardi formulas, with training loads.
Women's health
Cycle, fertility and pregnancy dates, with their limits clearly stated.
- Ovulation calculatorEstimate your ovulation date, fertile window, next periods and expected due date from your cycle length.
- Period calendarProject your next six cycles: period dates, ovulation day and the fertile window, from your own cycle length.
- Pregnancy due date calculatorEstimate your due date from your last period or conception date, with gestational age, trimester and key milestones.
- Pregnancy weight gain calculatorSee the recommended pregnancy weight gain range for your pre-pregnancy BMI, and how your current gain compares.
Maths
Percentages, statistics and number theory, with the working shown.
- Percentage calculatorFive percentage calculations in one tool: percent of a number, share, change between two values, discount and increase.
- Mean, median and standard deviation calculatorPaste a list of numbers and get the mean, median, mode, range, and sample and population standard deviation.
- GCD and LCM calculatorFind the greatest common divisor and least common multiple of two or more whole numbers, with prime factors.
- Fraction calculatorAdd, subtract, multiply and divide fractions, with the answer in lowest terms, as a mixed number and as a decimal.
- Quadratic equation solverSolve ax² + bx + c = 0 with the quadratic formula, including complex roots, the vertex and the axis of symmetry.
- Right triangle calculatorSolve a right-angled triangle from any two sides: the third side, area, perimeter, angles and height to the hypotenuse.
- Combinations and permutations calculatorCalculate combinations and permutations of n items taken r at a time, with and without repetition.
- Rule of three calculatorSolve a proportion by cross-multiplication, in direct or inverse mode — recipes, prices, speeds and scaling.
- Roman numeral converterConvert numbers to Roman numerals and back, from 1 to 3999, with a strict check and a breakdown of each symbol.
Science & engineering
A scientific calculator, electricity, density, motion and screens.
- Scientific calculatorA full scientific calculator: trigonometry, logarithms, powers, roots, factorials and constants, in degrees or radians.
- Ohm's law calculatorCalculate voltage, current, resistance and power from any two of them, with Ohm's law and the power formulas.
- Density calculatorCalculate density, mass or volume from the other two, with reference densities for common materials.
- Speed, distance and time calculatorCalculate travel time, average speed or distance from the other two, with arrival time and break allowance.
- Screen PPI calculatorCalculate pixel density, physical dimensions, aspect ratio and the viewing distance at which pixels stop being visible.
Dates
Ages, durations and working days between two dates.
- Age calculatorWork out an exact age or the duration between two dates, in years, months, weeks and days.
- Business days calculatorCount working days between two dates, excluding weekends and any public holidays you enter.
- Countdown calculatorCount the days, weeks, months and working days until a date — or since one, for a date in the past.
- Hours worked calculatorCalculate hours between two times, minus an unpaid break, in hours and minutes and in decimal hours for payroll.
- Add or subtract days from a dateAdd or subtract days, working days, weeks, months or years from a date, with the week number and day of year.
Conversion
Units, number bases, file sizes, aspect ratios and kitchen measures.
- Unit converterConvert mass, length, volume, area, temperature, speed, pressure and data between metric and imperial units.
- Download time calculatorWork out how long a file takes to download or upload at a given connection speed, accounting for bits against bytes.
- Cooking measurement converterConvert cups, spoons and millilitres to grams for common ingredients, and scale a recipe up or down.
- Binary, hex and decimal converterConvert numbers between binary, octal, decimal and hexadecimal, with bit count, bytes and nibble grouping.
- Aspect ratio calculatorFind the aspect ratio of any image or screen, and the missing dimension when resizing without distortion.
Home & DIY
Paint, tiles, concrete and what your appliances cost to run.
- Electricity cost calculatorWork out what an appliance costs to run per use, day, month and year, including the cost of standby power.
- Paint calculatorWork out how much paint a room needs from its dimensions, the number of coats and the coverage on the tin.
- Tile calculatorWork out how many tiles and boxes you need for a floor or wall, with an allowance for cuts and breakage.
- Concrete calculatorCalculate the concrete volume for a slab, footing or round column, with the number of bags and a waste allowance.
Car
Fuel, charging an electric car, and what a car loses in value.
- Fuel cost calculatorWork out what a journey costs in fuel, in litres per 100 km, miles per gallon or kilometres per litre.
- Car depreciation calculatorEstimate how much value a car loses each year, its resale value, and depreciation per month and per kilometre.
- Electric car charging cost calculatorCalculate the cost and time of charging an electric car, with charging losses, fast-charger taper and cost per 100 km.
Everyday
Tips, sleep and grades — the small sums that come up constantly.
- Tip calculatorSplit a bill, add a tip at any percentage, and round the total so the table pays a clean number.
- Weighted grade average calculatorCalculate a weighted average of grades on a 4, 10, 20 or 100 scale, and the mark needed on what is left.
- Sleep calculatorFind the bedtimes and wake times that line up with 90-minute sleep cycles, so you wake at the end of a cycle.
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