Math
Percentages, fractions, areas and the everyday arithmetic behind them.
16 calculators
- Percentage CalculatorThree questions get asked as one. Pick which of them you mean, put in the two numbers, and the working is shown underneath.
- Percentage Change CalculatorTwo numbers, before and after. This gives the change as a percentage, as a plain difference and as a multiple, because each answers a different question.
- Area CalculatorPick a shape and fill in the measurements it needs. The extra fields are ignored for shapes that do not use them.
- Circle CalculatorEvery measurement of a circle follows from any one of them. Enter whichever you actually have and the rest come out.
- Right Triangle CalculatorGive any two sides and the third follows, along with both angles. This is the calculation behind squaring up a deck, a wall or a fence line.
- Fraction CalculatorTwo fractions, one operation, and the answer in lowest terms. The mixed number and the decimal come with it, along with the common denominator that was used.
- Ratio CalculatorSimplify a ratio, scale it, or solve a proportion. Leave the last number at zero and it will be solved for instead.
- Average CalculatorPaste your numbers separated by commas, spaces or new lines. You get the mean along with the median, mode and spread, because the mean alone can be misleading.
- Exponent CalculatorRaise any number to any power. Negative exponents, fractions and decimals all work, and the rule being used is shown under the answer.
- Square Root CalculatorThe square root as a decimal and, when the number allows it, in simplified radical form. Cube roots and any other root are on the same page.
- Probability CalculatorEnter the chance of each of two independent events. You get both, either, neither and exactly one, plus what happens if you repeat the first event many times.
- Random Number GeneratorPick numbers between any two values. Change the seed to draw again - the same seed always gives the same numbers, so a shared link shows the same draw.
- Scientific CalculatorType an expression or tap it out. The answer updates as you go, there is no equals key to press, and the link in the address bar carries your working so you can send it to someone.
- Roman Numeral ConverterType a number for the numerals, or type numerals for the number. It works in both directions at once, and shows how the answer is put together letter by letter.
- Slope CalculatorEnter two points and this gives you the slope, the equation of the line through them, the angle it makes with the horizontal, and the distance between the points.
- Standard Deviation CalculatorPaste your numbers separated by commas, spaces or new lines. You get the standard deviation both ways, the variance, the mean, the median and the spread, with the steps shown.
Everyday arithmetic, with the working shown
The percentage calculators cover the three questions people ask most: what is X percent of Y, X is what percent of Y, and how much did something go up or down. Percentage change always measures against the starting value, which is why a 50 percent fall followed by a 50 percent rise does not get you back where you began.
For shapes, use the area, circle, right triangle and slope calculators. For data, the average and standard deviation calculators work on a list of numbers you paste in. The fraction calculator gives the answer as a simplified fraction and as a decimal.
Every calculator shows the formula and the steps behind its answer, so you can check the method or follow it by hand for homework.