Math & Science Calculators
Homework and lab work share a problem: the answer alone is worthless if you have to explain how you got it. The calculators in this section print the formula with your values substituted, so the output doubles as a worked example you can copy into a notebook and defend. That covers the chemistry and physics staples, the statistics that first-year courses assume you already know, and the grade arithmetic students run more often than any of it.
Chemistry problems usually start at the Molar Mass Calculator, which parses a formula like Ca(OH)2 and totals the atomic weights, with the Dilution Calculator and Density Calculator covering the rest of a lab write-up. Physics coursework leans on the Ohm's Law Calculator, Kinetic Energy Calculator and Half-Life Calculator. For statistics, the Z-Score Calculator converts a raw value into standard deviations from the mean, and the Percent Error Calculator compares a measurement against the accepted figure.
Precision is the usual sticking point. A calculator will happily return ten digits, but a result can only carry as many significant figures as your least precise measurement, which is what the Sig Fig Calculator is for. Check units before you trust a number: mixing grams with kilograms or centimeters with meters produces answers that are wrong by orders of magnitude and still look plausible. Z-scores assume a roughly normal distribution, and grading scales differ between US and UK institutions.
15 free tools — all run entirely in your browser.
Frequently asked questions
How do I calculate the molar mass of a compound?
Type the chemical formula into the Molar Mass Calculator using standard notation, including parentheses and subscripts, and it sums the standard atomic weights of each element. The result is given in grams per mole, along with the per-element breakdown so you can check the parsing matched the compound you meant. Double-check the capitalization, since Co is cobalt and CO is carbon monoxide.
What is the difference between percent error and percent difference?
Percent error compares a measured value against a known or accepted value, dividing the absolute difference by the accepted value, which is what lab reports ask for. Percent difference compares two measurements when neither is the reference, dividing by their average instead. The Percent Error Calculator does the first; using it when you have no accepted value will overstate or understate the gap.
What does a z-score actually tell me?
It says how far a value sits from the mean, measured in standard deviations. A z-score of 1.5 means the value is one and a half standard deviations above average; a negative score is below it. For a roughly normal distribution you can read that as a percentile, which is how test scores and quality thresholds are usually interpreted. Skewed data breaks that reading.