About ChemistryStepByStep

ChemistryStepByStep is a free collection of chemistry calculators: molarity, dilution, stoichiometry, gas laws, pH, molar mass, and more. The goal is to show the actual formula and the real intermediate steps behind an answer, not just a final number, so you can check your own work instead of copying a result you can't verify.

Everything runs in your browser. Your numbers never leave your device.

Where the constants come from

Every atomic weight used across these calculators comes from IUPAC's official Standard Atomic Weights table (iupac.qmul.ac.uk/AtWt), not a value typed from memory. The gas constant used in the ideal gas law calculator comes from NIST's CODATA reference (physics.nist.gov). Both are cited directly in the site's code, and both are cross-checked against known real-world results — for example, the weighted-average atomic mass calculator's chlorine example reproduces chlorine's published atomic weight (35.45) from its two real isotopes, and the ideal gas law calculator reproduces the textbook STP molar volume (22.414 L/mol) from the cited gas constant alone.

The formulas themselves aren't invented here — they're standard, textbook chemistry: the molarity and dilution equations, the ideal and combined gas laws, the Henderson-style pH relationship, first-order half-life decay, and IUPAC's own definitions for molar mass and empirical formula. The calculators exist to make those standard methods fast and show the work, not to introduce a new way of doing the chemistry.

Who built this

ChemistryStepByStep is built and maintained by Elbert Ballo. Every constant above is checked against its cited primary source before anything ships, and a second, independent pass re-derives each worked example by hand rather than trusting the code to grade itself.