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Stoichiometry Calculator

Convert between grams, moles and liters at STP across a balanced equation using mole ratios.

Stoichiometry Calculator works straight from this page — free, instant, nothing to install. You will find it under Chemistry, with Chemical Equation Balancer and Empirical Formula Calculator for the neighbouring cases.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Stoichiometry Calculator?

Convert between grams, moles and liters at STP across a balanced equation using mole ratios.

When would I actually use this?

Preparing a solution at a stated concentration, working out how much of a reagent a reaction needs, and converting between mass, moles and volume.

What is the most common mistake?

Confusing molarity with molality. One is per litre of solution and the other per kilogram of solvent; they diverge as concentration rises, and only one of them is temperature-independent.

How is Stoichiometry Calculator different from Chemical Equation Balancer?

They sit next to each other but answer different questions. Chemical Equation Balancer: balance any chemical equation instantly by solving the element matrix exactly — even tricky redox reactions. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Empirical Formula Calculator is the closest one after this: Find the empirical (and molecular) formula from mass percentages or experimental masses.

What else is worth having open alongside it?

Limiting Reactant Calculator and Molar Mass Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Atomic masses are the IUPAC standard values. Results assume ideal behaviour and standard conditions unless the tool says otherwise — real solutions deviate, and lab work needs lab measurement.

Further reading

All guides →
How-toHow to Solve Stoichiometry Problems: Grams to Moles to Ratio to GramsEvery problem in the chapter is the same four moves. The mole ratio is the hinge, and it is the step students lose — worked here end to end, limiting reactant and percent yield included.ExplainerMolarity Is per Litre of Solution, Not per Litre of Water0.5 mol in 2 litres is 0.25 mol/L. The two litres have to be the finished solution — adding solute to two litres of water gives something else, and the label will be wrong.How-toHow to Calculate Molar Mass, Including Parentheses and HydratesMultiply each atomic weight by its subscript and add. The only three places the arithmetic goes wrong are a subscript after a closing bracket, the hydrate dot, and a capital letter typed as a lowercase one.ExplainerAn Absorbance of Two Means One Per Cent of the Light Gets Through6,220 M⁻¹cm⁻¹ at 100 µM through 1 cm gives A = 0.622, and 23.9 % of the light emerges. Double the path length and A doubles to 1.244 — the scale is logarithmic, and that is where it breaks.ExplainerThe Same Burette Reading Gives Two Different Concentrations24.80 mL of 0.1 M titrant into 25.00 mL of analyte gives 0.0992 M — or 0.0496 M if the analyte releases two protons. The stoichiometry is typed, not measured.ExplainerEighty Per Cent Five Times Over Leaves a Third8 grams obtained where 10 were possible is an 80 % yield. Chain five such steps and 32.8 % of the starting material reaches the end — which is why a long synthesis is judged step by step.