Calculators

Add or subtract days, weeks, months, years or working days from a date.

Work out an exact age in years, months and days, plus the next birthday.

Convert between 6 angle units, with the conversion factors shown so the result can be checked.

Convert between 10 area units, with the conversion factors shown so the result can be checked.

Find the aspect ratio of a size, and scale it to a new width or height without distortion.

Find the mean, median and mode of a list of numbers.

Calculate body mass index in metric or imperial units, with the healthy range for your height.

Find radius, diameter, circumference and area from whichever one you know.

Project savings growth with compounding and regular contributions, and see the year-by-year balance.

Distance, midpoint, slope, the equation of the line, section formula and triangle area from coordinates - each with the formula worked out.

Convert between 10 digital storage units, with the conversion factors shown so the result can be checked.

Count the days, weeks and working days between two dates, plus the calendar difference in years and months.

Find the sale price and how much you save, including stacked discounts.

Find the straight-line distance between two points, with the Pythagorean working shown step by step.

Convert between 7 energy units, with the conversion factors shown so the result can be checked.

Simplify fractions, convert them to decimals, or turn a decimal back into a fraction.

Find the greatest common divisor and lowest common multiple of two or more numbers.

Convert between 12 length units, with the conversion factors shown so the result can be checked.

Calculate the monthly payment on a loan, the total interest, and how the first year splits between interest and principal.

Turn cost and selling price into profit, margin and markup - three numbers people mix up.

Find the point exactly halfway between two coordinates.

Convert a number between binary, octal, decimal, hexadecimal and any base up to 36.

Work out a percentage of a number, what percent one number is of another, or the whole from a part.

Find the percentage increase or decrease between two values.

Convert between 6 pressure units, with the conversion factors shown so the result can be checked.

Check whether a number is prime, and factorise it if it is not.

Find the hypotenuse, or a missing side, of a right-angled triangle.

Simplify a ratio and see it as a decimal, as percentage shares, and scaled to 1.

Area, perimeter, diagonal and aspect ratio of a rectangle.

Convert numbers to Roman numerals and back, with strict validation of the notation.

Add tax to a net amount, or work backwards to find the net amount from a gross figure.

Find the point dividing a line segment in a given ratio, internally or externally.

Calculate interest charged on the principal only, with no compounding.

Find the slope of a line through two points, plus its angle, intercept, perpendicular slope and equation.

Convert between 6 speed units, with the conversion factors shown so the result can be checked.

Calculate sample and population standard deviation and variance, with the full summary.

Mean, median, mode, range, quartiles, variance and standard deviation for a list of numbers.

Convert between Celsius, Fahrenheit, Kelvin and Rankine, with absolute zero enforced.

Convert between 8 time units, with the conversion factors shown so the result can be checked.

Work out the tip and split the bill, with an option to round the total up.

Area, perimeter, angles and type of a triangle from its three sides.

Add or remove VAT at any rate, with the net, VAT and gross figures shown separately.

Volume and surface area of a cube, box, sphere, cylinder or cone.

Convert between 14 volume units, with the conversion factors shown so the result can be checked.

Convert between 9 weight and mass units, with the conversion factors shown so the result can be checked.

Average values where some count for more than others - grades, scores or prices.