Free Chemistry Calculators

Solutions, stoichiometry, acids and bases — each one printing the substituted formula rather than only the answer, so you can check where a number came from.

43 free tools
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A 3 tools

Activation Energy Calculator Solves the Arrhenius equation for activation energy from rate constants at different temperatures. Air Fuel Ratio Calculator Converts between air-fuel ratio and lambda for a chosen fuel and computes AFR from mass flows. Average Atomic Mass Calculator Computes average atomic mass from isotope masses and abundances, or solves a missing abundance.

B 2 tools

Beer-Lambert Law Calculator Solve A = ε × l × c for any term and convert between absorbance and transmittance. Boiling Point Calculator Finds the boiling point of a liquid at a chosen pressure or altitude, using Clausius-Clapeyron.

C 4 tools

Calibration Curve Calculator Fits a least-squares calibration line to standards and reads unknown concentrations off the fit. Carbon Dating Calculator Estimates a radiocarbon age from the fraction of carbon-14 remaining or a measured activity. Chemical Equation Balancer Balance any chemical equation and get an atom-by-atom check and the reaction type. Colligative Properties Calculator Computes boiling point elevation and freezing point depression, with the van t Hoff factor.

D 1 tool

Degree of Unsaturation Calculator Computes the degree of unsaturation of a molecular formula containing C, H, N, O and halogens.

E 4 tools

Electron Configuration Calculator Get the full and noble-gas electron configuration and orbital diagram for any element. Empirical Formula Calculator Convert element percentages or masses into an empirical and molecular formula. Entropy Change Calculator Find the standard entropy change of a reaction from S° values, or the ΔS of a process from heat. Equilibrium Constant Calculator Get Kc from equilibrium concentrations, convert it to Kp with the Δn correction, and read the position.

G 1 tool

Gibbs Free Energy Calculator Calculate ΔG from enthalpy, entropy and temperature, and find the crossover temperature.

H 2 tools

Half-Life Calculator Convert half-life, decay constant and mean lifetime, and find the amount remaining. Henderson-Hasselbalch Calculator Find buffer pH from pKa and the base-to-acid ratio, or the amounts needed for a target pH.

I 1 tool

Ideal Gas Law Calculator Solve PV = nRT for pressure, volume, moles or temperature in mixed units, with molar volume and STP.

M 8 tools

Mass Percent Calculator Work out mass percent, volume percent or w/v percent of a solution and convert it to ppm. Michaelis-Menten Calculator Get enzyme velocity from Vmax, Km and substrate, or fit both parameters from your velocity data. Molality Calculator Get molality in mol/kg from solute and solvent mass, then convert it to molarity with density. Molar Mass Calculator Type a chemical formula and get its molar mass in g/mol with a per-element breakdown. Molar Ratio Calculator Convert an amount of one species into another with the balanced ratio and find the limiting reactant. Molarity Calculator Solve for molarity, moles, solute mass or volume by leaving the unknown field blank. Mole Fraction Calculator Work out the mole fraction and mole percent of every component from moles or from masses. Moles to Grams Calculator Convert between moles, grams and particle count for any substance in either direction.

N 3 tools

Nernst Equation Calculator Find cell potential under non-standard conditions from E, n, the reaction quotient and temperature. Net Ionic Equation Calculator Get balanced molecular, complete ionic and net ionic equations with spectator ions identified. Normality Calculator Convert molarity to normality using the equivalence factor, with equivalent weight and mass needed.

O 1 tool

Osmotic Pressure Calculator Calculate osmotic pressure from molarity, van 't Hoff factor and temperature, or solve for molar mass.

P 5 tools

Partial Pressure Calculator Apply Dalton's law to split a total pressure among up to four gases in a mixture. Percent Composition Calculator Get the mass percent of every element in a chemical formula, plus grams in a real sample. Percent Yield Calculator Work out percent yield, or solve for theoretical or actual yield from the other two. pH Calculator Convert between pH, pOH and ion concentrations, or find pH from concentration and Ka. pKa and Ka Calculator Convert Ka, pKa, Kb and pKb, or derive Ka from a measured pH and acid concentration.

R 2 tools

Raoult's Law Calculator Find the vapour pressure above an ideal mixture and the composition of the vapour. Reaction Rate Constant Calculator Find the rate constant and half-life for a zero, first or second order reaction.

S 3 tools

Serial Dilution Calculator Plan a full serial dilution series with per-tube concentrations and pipetting volumes. Solution Concentration Calculator Rewrite one solution strength as molarity, molality, g/L, percent, ppm and mole fraction. Solution Dilution Calculator Solve the dilution equation for stock volume, diluent volume or final concentration.

T 1 tool

Titration Calculator Find an unknown concentration or the titrant volume at the equivalence point.

V 1 tool

Vapour Pressure Calculator Find a pure liquid's vapour pressure at any temperature, by Antoine or Clausius-Clapeyron.

W 1 tool

Water Hardness Calculator Convert water hardness between grains, ppm, mmol/L and the German and French degrees.

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Built around a real formula parser

Most online chemistry tools ask you to type in a molar mass you already worked out somewhere else. These read the formula itself: nested parentheses, hydrates written with a dot, multi-letter symbols and subscripts all parse, and an element symbol that does not exist is rejected by name instead of being quietly treated as zero. The atomic weights come from the IUPAC and NIST tables, linked on the page.

The approximations are named, not hidden

A pH calculation for a weak acid can be done with a simplifying assumption or with the full quadratic, and the two disagree exactly where students are most often marked wrong. These tools solve the quadratic and say on screen which route was used. Henderson-Hasselbalch has a section on where it stops being valid, because a buffer equation applied outside its range returns a confident wrong answer.

What these pages will not do

They describe how a calculation works. None of them gives laboratory procedure, handling advice or safety instruction, because that belongs with the person responsible for the bench you are standing at, not with a web page.

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All 1141 free tools are organised into 22 categories.