Maths calculators
Solve percentages, ratios and averages, with the operation and denominator made explicit.
Choose the right tool
Percentage-point change is different from relative percentage change. Arithmetic, geometric and harmonic means answer different questions; choose the one matching the problem.
Before you calculate
Zero denominators and inputs outside a formula's domain are rejected. Use consistent units before comparing or combining quantities.
14 calculators
Percentage of a number ↗
Find a specified percentage of an amount.
MathsPercentage change ↗
Measure increase or decrease relative to the original non-zero value.
MathsAverage speed ↗
Calculate average speed using distance and non-zero elapsed time.
MathsPercentage-point difference ↗
Find an absolute difference between two percentages.
MathsOriginal amount before increase ↗
Recover the original amount before a percentage increase.
MathsOriginal price before discount ↗
Recover an original price from a discounted amount.
MathsSuccessive discount price ↗
Apply one discount followed by a second discount to the reduced price.
MathsPart as percentage of total ↗
Express a part relative to a total.
MathsDivide total by a ratio ↗
Calculate the first share of a total divided in a two-part ratio.
MathsMean of three values ↗
Calculate the arithmetic mean of three numbers.
MathsWeighted mean of two values ↗
Average two values with different non-negative weights.
MathsGeometric mean of two values ↗
Find the two-value geometric mean.
MathsHarmonic mean of two rates ↗
Average two positive rates using the harmonic mean.
MathsRoot mean square of two values ↗
Calculate the square root of the mean of two squared values.