Math & Geometry Calculators

Percentages, fractions, exponents, ratios, standard deviation and the area, volume and perimeter of common shapes.

Most everyday maths is percentages and fractions. The percentage calculator answers the three usual questions, and the percent increase and percent decrease calculators measure change between two values. The fractions calculator adds, subtracts, multiplies and divides, and the simplify fractions calculator reduces the result.

The geometry tools work out the area, perimeter, surface area and volume of common shapes, and the statistics tools cover the standard deviation, the z-score and the confidence interval. Each page shows its formula and worked examples so you can check the answer by hand. Round only at the last step: carrying extra digits through a multi-step problem keeps the answer closer to the true value, and a result that looks too large or too small is worth a second look before you rely on it.

Popular math & geometry calculators

• Percentage CalculatorPercent of a number, one number as a percent of another, and more.
• Fraction CalculatorArithmetic with fractions and mixed numbers, shown as a fraction.
• Standard Deviation CalculatorMean, variance and standard deviation for a list of numbers.
• Area CalculatorArea of rectangles, circles, triangles and other shapes.

All math & geometry calculators

• Percentage CalculatorPick the question you need answered, enter two numbers and get the result instantly, whether you want a percent change, a percentage difference or X% of Y.
• Area CalculatorChoose a shape, enter the measurements you know and get its area in the unit you prefer. Triangles can be solved from sides, angles, or a hypotenuse and a leg.
• Volume CalculatorPick a solid, enter its dimensions in whichever units you measured them in, and get the volume in the cubic unit you prefer. Boxes, cubes, cylinders, cones, spheres and triangular prisms are covered.
• Exponent CalculatorType a base and an exponent, whole, negative or fractional, and get the power straight away. A power with no real value, or one too large to store, is reported as such instead of as a wrong number.
• Fraction CalculatorWork with simple fractions, mixed numbers and decimals in basic mode, or type a whole expression with brackets in advanced mode. Every answer comes as a decimal and as a mixed fraction.
• Combination CalculatorEnter how many items you can choose from and how many you will pick, and the calculator returns the number of different selections. Tick the repetition box when the same kind of item may be picked more than once.
• Confidence Interval CalculatorGet a confidence interval for a single average, or for the gap between two groups measured as means or proportions, in absolute or relative terms. Choose your confidence level and read both the two-sided and one-sided bounds.
• Greatest Common Divisor (GCD) CalculatorPaste or type two or more numbers and get their greatest common divisor in one click. Whole numbers, decimals and negatives all work, and zero is handled too.
• Percentage Decrease CalculatorChoose whether you want to take a percentage off a number or find the percentage drop between two values, fill in the fields and press Calculate. The drop is (original − new) ÷ original × 100.
• Percentage Increase CalculatorChoose whether to add a percentage to a number or to measure how much one value grew into another, enter the figures and press Calculate to get the increased value or the percent rise, along with the absolute difference.
• Perimeter CalculatorPick a shape, enter its measurements in any mix of units and read the perimeter in the unit you choose. Each of the nine shapes has its own formula, from 4a for a square to a series approximation for an ellipse.
• Ratio CalculatorFill in three of the four numbers in a:b = c:d, leave one empty and read off the missing value. Notes on simplifying and combining ratios, odds and screen aspect ratios are included.
• Scientific Notation Calculator & ConverterSwitch between the converter and the calculator at the top. Convert a number between decimal and scientific form, or do arithmetic on two numbers written in e-notation.
• Simplify Fractions CalculatorType a fraction as numerator/denominator and the calculator reduces it to lowest terms, showing a mixed number when the fraction is improper. You can check any result by hand with the greatest common divisor, as in 48/180 = 4/15.
• Square Root CalculatorType a positive number and the calculator returns its principal square root, exact for perfect squares and rounded to six decimals otherwise. Zero and negative numbers are rejected.
• Standard Deviation CalculatorPaste your numbers, choose sample or population, and get the standard deviation with the variance, mean, standard error of the mean, range and count. A second mode handles proportions and rates.
• Surface Area CalculatorChoose a shape, enter its measurements in any mix of units, and get the total outside area in the square unit you prefer. Boxes, cubes, cylinders, cones, spheres and triangular prisms are covered.
• Z Score CalculatorEnter a raw score with the mean and standard deviation of its distribution to get the z score and the areas above, below and outside it. Or enter a probability to get the matching critical z score.