Math

Percentage of / change / reverse plus mean, median, mode, and standard deviation — free math helpers for study and everyday work.

• Random Number GeneratorPick random numbers between any minimum and maximum, with or without repeats, or switch to a coin flip, dice roll or lottery quick pick.
• Password Generator: Random or MemorableCreate strong passwords you can actually remember. Every password comes with a memory hint, a strength score and crack-time estimate, and it is generated on your device, never sent anywhere.
• Percentage calculatorThree everyday percentage identities — part of whole, percent change, and reverse — with wording that matches how people actually search.
• Ratio CalculatorSimplify a ratio, find the missing term of a proportion, or scale a ratio up, down or to a total. Every answer shows the GCD or cross-multiplication step by step.
• Slope CalculatorEnter two points to find the slope (rise over run), the y-intercept and the line's equation in slope-intercept, point-slope and standard form, plus the angle, distance and midpoint — all shown step by step.
• Area converterConvert any area via the SI square metre. Exact BIPM / NIST factors — see the arithmetic for your input, plus a table of every equivalent.
• Length converterConvert any length via the SI metre. Factors are exact international definitions — see the arithmetic for your input, plus a table of every equivalent.
• Temperature converterConvert any temperature via the SI Kelvin. Exact textbook / ITS-90 relations — see the arithmetic for your input, plus a table of all five scales (°C, °F, K, °R, °Ré) with common temperatures: body temperature, freezing and boiling water, oven settings.
• Volume converterConvert any volume via the SI cubic metre. Exact BIPM / NIST factors — see the arithmetic for your input, plus a table of every equivalent.
• Weight converterConvert any mass via the SI kilogram. Factors are exact international definitions — see the arithmetic for your input, plus a table of every equivalent.
• Statistics calculatorPaste a list of numbers to see center and spread: mean, median, mode, range, and standard deviation for study or small datasets.
• Speed converterConvert any speed via the SI metre per second. Exact international factors, the arithmetic for your input, all equivalents and pace per km / mile.
• Power converter (kW, hp, PS)Convert any power unit via the watt. Exact factors, the arithmetic for your input, all equivalents and a car-engine table of kW, PS and hp.
• Combination and Permutation CalculatorEnter how many fields there are (N) and how many you pick (k). You get the exact number of combinations or permutations, written out in full and in scientific notation, plus the odds of guessing everything with one ticket. Example: picking 6 numbers out of 40, as in many 6/40 lotteries, gives 3,838,380 combinations.
• Fraction calculatorAdd, subtract, multiply or divide two fractions or mixed numbers. The answer is simplified and shown as an improper fraction, a mixed number and a decimal, with every step of the working.
• Mean, median and mode calculatorPaste a list of numbers to get the mean, median, mode and range, plus count, sum and standard deviation, with the sorted list shown.
• Midpoint calculatorEnter two points to get the midpoint of the segment between them in 2D or 3D, the distance AB and the slope, with every step shown.
• Paint calculatorEnter the wall length, height, doors, windows and coats. You get the area to paint, the litres or gallons of paint and how many cans to buy.
• Volume calculatorPick a shape, enter its dimensions in mm, cm, m, in, ft or yd and get the volume in m³, litres, cm³, ft³, yd³ and US/UK gallons — with the formula worked out using your numbers.