Free science calculators

Physics, chemistry and study tools that show every substitution, so you can see where each number came from.

Ohm's Law CalculatorGive any two of voltage, current, resistance and power to find the other two.Speed, Distance and Time CalculatorFind speed, distance or time from the other two, in km, miles or metres.SUVAT Equations CalculatorSolve constant-acceleration problems when you know any three of s, u, v, a, t.Density, Mass and Volume CalculatorFind density, mass or volume with unit conversion and a float-or-sink check.Molar Mass CalculatorType a formula like Ca(OH)2 for molar mass, percent composition and moles.Molarity and Dilution CalculatorWork out concentration, moles of solute, or how much solvent to add when diluting.Scientific Notation ConverterConvert to scientific, engineering and E-notation with chosen significant figures.Weighted Grade CalculatorCombine scores and weights, then see the mark needed on the final to hit a target.

Using these tools well

Science questions go wrong in small, boring ways: a unit left in grams instead of kilograms, a formula rearranged with the wrong sign, a power of ten dropped on the way. Each calculator here writes out the formula, the substitution and the units, so a slip shows up as a line that does not look right instead of a mystery answer.

A good habit is to estimate first. If a 60 W bulb on a 12 V supply gives you an answer of 50 amps, your instinct should object before the calculator does. Run your own working, run ours, and compare. Everything calculates in your browser, nothing you enter is sent anywhere, and every page works on a school laptop or a phone. If you want the idea behind a topic rather than the arithmetic, the study guides are written for exactly that.