Free online calculators

Work out your monthly mortgage payment, total interest and loan-to-value for a repayment or interest-only mortgage.

Work out your UK take-home pay after income tax, National Insurance, student loan and pension, a year, month and week. Includes Scottish tax rates.

Work out Stamp Duty Land Tax on a home in England or Northern Ireland, including first-time buyer relief and the second home surcharge.

See how savings grow with compound interest and monthly payments. Free, with the formula and a worked example.

See how your pension pot could grow by retirement with your and your employer's contributions, tax relief, investment growth and charges.

Work out the monthly repayment on a personal loan or car loan, the total interest, and how the balance falls year by year.

Add VAT to a price or take it off, at 20%, 5% or any rate. Shows the VAT amount and the prices with and without VAT.

Work out profit margin and markup from cost and price, or the selling price you need for a target margin or markup.

Work out the income tax and Class 4 National Insurance you'll pay as a self-employed sole trader, and how much to set aside each month.

Work out the day rate and hourly rate you need to charge as a freelancer or contractor, allowing for holidays, costs and unpaid admin time.

Work out the statutory interest and compensation you can claim on a late business invoice in the UK: 8% plus the Bank of England base rate.

Work out how much paint you need for a room's walls or ceiling, allowing for doors, windows and the number of coats, with tin sizes to buy.

Work out how much concrete you need for a slab, base or path, with extra for waste and an approximate weight.

Work out how many tiles and boxes you need for a floor or wall, allowing for grout gaps and extra for cuts and breakages.

Work out how many tonnes of gravel, MOT Type 1 or sand you need for a driveway, path or base, and how many bulk bags or small bags that is.

Work out how many rolls of wallpaper you need for a room or feature wall, allowing for the pattern repeat.

Find a roof's pitch from its rise and run, or the roof height from the pitch. In degrees, rise in 12 and percent, with the rafter length.

Convert watts to amps, or amps to watts, for DC, single-phase or three-phase AC, with power factor. Shows the working.

Find voltage, current or resistance from the other two using Ohm's law, or a heater element's resistance from its watts. Shows the power.

Check the voltage drop on a copper cable run against the UK wiring regulations' 3% and 5% limits, with the longest run and smallest cable that pass.

Work out a gear ratio from the number of teeth, and the output speed and torque from the input, allowing for efficiency.

Find the right tap drill size for metric, UNC and UNF threads, at any thread percentage, with the nearest standard drill and the thread it gives.

Work out the tightening torque and clamp force for metric and UNC/UNF bolts by grade and lubrication, from 4.6 to 12.9 and SAE Grade 2, 5 and 8.

Work out your body mass index (BMI) in cm and kg, feet and inches, or stones and pounds, and see the healthy weight range for your height.

Work out how many calories you need a day to keep your weight steady, or to lose or gain weight gradually, from your age, size and activity.

Work out your baby's due date from your last period, conception date, IVF transfer or a dating scan, and see how many weeks pregnant you are.

Work out how many UK units of alcohol are in a drink from its size and strength, and how that compares with the weekly guideline.

Work out a percentage of a number, what percentage one number is of another, percentage change, and adding or taking off a percentage.

A free online calculator with a big keypad, percentages, memory and a history of your sums. Switch to scientific mode for trig, logs and powers.

A free online scientific calculator: sin, cos, tan and inverses in degrees or radians, logs, powers, roots, factorials, π and e, with history.

Work out the area of a rectangle, triangle, circle, trapezium, parallelogram or ellipse in m², ft², acres or hectares, with the formula.

Work out the volume of a box, cylinder, sphere, cone or pyramid in m³, litres, ft³ or gallons, with the formula for each shape.

Simplify a ratio, find the missing number in an equal ratio, or share an amount in a ratio such as 2:3:5. With the working shown.

Work out exact age in years, months and days from a date of birth, plus total days and weeks lived and the days until the next birthday.

Count the days, weeks and weekdays between two dates, with the option to include the end date.

Count the working days between two dates, leaving out weekends and UK bank holidays for England and Wales, Scotland or Northern Ireland.

Work out the hours in a shift from start and finish times, minus breaks, in hours and minutes and decimal hours, plus weekly hours and pay.

Convert stones and pounds to kilograms, and kg to stones and pounds. Also grams, ounces, pounds, tonnes and UK and US tons.

Convert centimetres to inches, feet and inches, metres, millimetres, yards, kilometres and miles, and back again.

Convert temperatures between Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Rømer, Newton and Delisle, with the formulas.

Convert litres to UK and US gallons, pints, fluid ounces, cups, millilitres and cubic metres, and back again.