Stoichiometry Calculators: Moles, Atoms and Mass

Use these stoichiometry calculators to work with the quantities of atoms, moles, and mass in chemistry problems. Convert Atoms to Moles helps you move between particle counts and amounts of substance, while Avogadro's Number helps you check the relationship behind that conversion. Use Atomic Mass and Molecular Mass (GMV Law) when you need mass values for a substance.These tools are useful for students checking homework, teachers preparing examples, and anyone working through basic chemical calculations. Choose the calculator that matches the quantity you know and the result you need.

C1V1 = C2V2

Find the volume of stock solution needed for a dilution. Enter the stock concentration, desired concentration, and desired final volume.

Convert Atoms to Moles

Convert a number of atoms into moles using Avogadro’s number. Enter a positive value in the Number of Atoms field to see the result in mol.

Mass Spectrometry m/z

Calculate the mass-to-charge ratio (m/z) of an ion from its neutral mass, charge number and adduct mass. Handles protonated, sodiated, ammoniated and multiply charged ions.

Water Hardness

Enter the measured calcium and magnesium concentrations and this water hardness calculator converts them to total hardness in mg/L as CaCO₃, classifies the water from soft to very hard, and shows the result in grains per gallon, German and French degrees.

Kohlrausch's Law

Calculate the limiting molar conductivity of any electrolyte at infinite dilution from its ionic conductivities and stoichiometric coefficients, using Kohlrausch's law of independent ion migration.

Debye–Hückel Activity Coefficient

Estimate the activity coefficient of an ion in aqueous solution using the Debye–Hückel limiting law, extended equation, or Davies equation. Enter the ionic strength, ion charge, and temperature to get γ and log₁₀ γ.

Avogadro's Number

Estimate Avogadro’s number from the number of particles in a crystal unit cell, molar mass, density, and unit cell volume. Enter all four values in the units shown.

Molecular Mass (GMV Law)

Estimate a gas’s molar mass from its density relative to hydrogen. Enter the Density of Gas and Density of Hydrogen in g/L to calculate vapour density and molecular mass.

Raoult's Law

Calculate the total vapor pressure and vapor-phase composition of an ideal two-component liquid mixture using Raoult's law. Enter the mole fractions and the pure vapor pressures of both components.

Empirical Formula

Enter the mass percentages or gram amounts of each element in a compound and instantly get its empirical formula, mole ratios, and the molar mass of the simplest formula.

Molecular Weight

Find molar mass from a chemical formula and see each element’s contribution. Optionally enter a sample mass to calculate moles and the number of molecules or formula units.

Molar Conductivity

Calculate the molar conductivity (Λm) of an electrolyte solution from its measured conductivity κ and molar concentration c. Enter both values with their units and get results in S·cm²/mol and S·m²/mol.

Molarity

Calculate the molarity (molar concentration) of a solution from the solute mass and molar mass, or directly from moles, and the total solution volume. Results are given in mol/L.

Normality

Calculate the normality (equivalent concentration) of a solution from its molarity, or from the mass and molar mass of the solute. Enter the equivalence factor and volume to get N in eq/L.

Percent Composition from Formula

Enter a chemical formula such as C6H12O6, Ca(OH)2 or CuSO4·5H2O and get the molar mass plus the mass percent of every element in the compound. Optionally override the atomic masses used.

Atomic Mass

Estimate an isotope’s atomic mass from its numbers of protons and neutrons. Enter the two counts to get an approximate result in atomic mass units (amu).

Boiling Point Elevation

Calculate the boiling point elevation of a solution from molality, the ebullioscopic constant Kb, and the van 't Hoff factor. Enter the pure solvent's boiling point to get the new boiling point in °C and °F.

Freezing Point Depression

Calculate the freezing point of a solution from molality, the cryoscopic constant (Kf), and the van 't Hoff factor. Enter your values to get the depression ΔTf and the new freezing point in °C and °F.

Percent Yield

Enter the actual yield you obtained and the theoretical yield from stoichiometry to instantly calculate the percent yield of your reaction, plus the difference between the two values. Supports g, mg, kg, lb and oz.

Molality

Calculate the molality of a solution in mol/kg. Enter the solute by mass or moles, plus the mass of the solvent, and get moles of solute and molality instantly.

Limiting Reactant

Enter the balanced-equation coefficients and available moles of two reactants to find which one is limiting, the maximum product yield, and how much excess reactant is left over.