Calculators

Work out any percentage of a number in one step, such as 15% of 200. Enter the percentage and the total and the result updates when you calculate,…

Find the percentage increase or decrease between an old value and a new value. Useful for prices, wages, traffic and results. A negative answer…

Add a percentage to any number, such as a price rise or a pay increase. Enter the starting value and the percentage to see the new total and the…

Take a percentage off a price to see the sale price and how much you save. Enter the original price and the discount to compare deals quickly.

Find the mean of three numbers instantly. Enter each value to see the sum and the average, which is handy for marks, measurements, readings and…

Calculate the area and circumference of a circle from its radius. Enter the radius in any unit and the results use the same unit squared for area.

Find the area and perimeter of a rectangle from its length and width. Use any consistent unit, and the area is returned in that unit squared.

Calculate the area of a triangle from its base and perpendicular height. Enter both measurements in the same unit to get the area in that unit squared.

Find the hypotenuse of a right-angled triangle from the two shorter sides. Enter sides a and b, and the calculator returns c using the formula a…

Calculate the volume of a cylinder from its radius and height, such as a tank or pipe. Enter both in the same unit to get volume in cubic units.

Find the volume and surface area of a sphere from its radius. Enter the radius in any unit to get volume in cubic units and area in square units.

Calculate average speed from distance and time. Enter the distance travelled and the time taken to see the speed, useful for trips, running and cycling.

Work out how far you will travel at a steady speed. Enter the speed and the time to get the distance, helpful for planning drives and rides.

Estimate how long a trip takes from the distance and your average speed. The answer is shown in hours and in minutes so you can plan arrival times.

Estimate the fuel cost of a drive. Enter the distance, your vehicle's consumption in litres per 100 km and the fuel price to see litres used and…

Calculate fuel economy in litres per 100 km from the distance driven and the fuel used. Compare vehicles, track efficiency over time and spot…

Estimate how much paint you need for the walls of a room. Enter the room size, ceiling height, the area of doors and windows and the number of coats.

Calculate the volume, slant height and surface area of a cone from its base radius and vertical height. Enter base radius and height to see volume,…

Find the volume and surface area of a pyramid with a square base from the base side length and the height. Enter base side and height to see volume,…

Calculate the volume, surface area and space diagonal of a cube from the length of one side. Enter side length to see volume, surface area and space…

Find the volume, surface area and space diagonal of a box or cuboid from its three dimensions. Enter length, width and height to see volume, surface…

Work out the area of a trapezoid from its two parallel sides and the perpendicular height between them. Enter parallel side a, parallel side b and…

Calculate the area and an accurate approximate perimeter of an ellipse from its semi-major and semi-minor axes. Enter semi-major axis and semi-minor…

Find the area and arc length of a sector, the slice of a circle, from the radius and the angle in degrees. Enter radius and angle to see sector area…

Calculate the area of a parallelogram from its base and the perpendicular height, not the slanted side. Enter base and height to see area when you…

Find the area, side length and perimeter of a rhombus when you know the lengths of both diagonals. Enter first diagonal and second diagonal to see…

Work out the area, perimeter and interior angle of any regular polygon from its number of sides and side length. Enter number of sides and side…

Calculate the area and perimeter of a regular hexagon from the length of one side, useful for tiles and paving. Enter side length to see area and…

Use Heron's formula to find a triangle's area when you know all three side lengths but not the height. Enter side a, side b and side c to see…

Find both acute angles and the hypotenuse of a right-angled triangle from the two shorter sides. Enter opposite side and adjacent side to see angle…

Calculate the length of the diagonal of a rectangle or screen from its length and width using Pythagoras. Enter length and width to see diagonal…

Find the area of a ring or washer, the space between two concentric circles, from the outer and inner radius. Enter outer radius and inner radius to…

Work backwards from the distance around a circle to its radius, diameter and area. Enter circumference to see radius, diameter and area when you…

Calculate the length of a circular arc and its chord from the radius and the central angle in degrees. Enter radius and central angle to see arc…

Find the volume and surface areas of a hemisphere, half a sphere, from its radius. Enter radius to see volume, curved surface area and total surface…

Calculate the area, perimeter and diagonal of a square from the length of one side. Enter side length to see area, perimeter and diagonal when you…

Find the area, height and perimeter of an equilateral triangle from the length of its side. Enter side length to see area, height and perimeter when…

Calculate the curved and total surface area of a cylinder from its radius and height, handy for paint and wrapping. Enter radius and height to see…

Solve ax² + bx + c = 0, where a is the x² coefficient, b the x coefficient and c the constant. A dash means there are no real roots. Enter…

Find the slope between two points on a line, along with the rise and run used to calculate it. Enter x1, y1, x2 and y2 to see slope, rise and run…

Calculate the straight-line distance between two points on a flat grid using the distance formula. Enter x1, y1, x2 and y2 to see distance when you…

Find the midpoint halfway between two points by averaging their x and y coordinates. Enter x1, y1, x2 and y2 to see midpoint x and midpoint y when…

Solve a proportion of the form a : b = c : d to find the missing fourth value. Enter a, b and c to see d when you calculate.

Convert a fraction to a decimal and a percentage by dividing the numerator by the denominator. Enter numerator and denominator to see decimal and…

Raise any base to any power, including negative and fractional exponents, and read the answer straight away. Enter base and exponent to see result…

Find the cube root of a positive number, the value that multiplied by itself three times gives your number. Enter number to see cube root when you…

Calculate the logarithm of a number to any base, including base 10, base 2 and natural logs. Enter number and base to see logarithm when you calculate.

Find the third side of a triangle when you know two sides and the angle between them. Enter side a, side b and angle c between them to see side c…