Four calculators, one panel.
Pick a mode below — type any valid chemical formula, including parentheses and hydrates, and every result comes with a full element-by-element breakdown.
Use parentheses for groups and a middle dot or asterisk for hydrates, e.g. CuSO4·5H2O.
The substance whose moles you want to find.
The amount of the substance you're starting with.
The substance whose mass you want to find.
The known amount of substance, in moles.
See what share of the total mass each element contributes.
A formula in, an answer out.
No manual required — but here's the entire flow in four moves.
Pick a mode
Molar mass for a formula alone. Grams to moles or Moles to grams for the two conversions. % composition to see each element's share of the mass.
Type the formula
Standard notation works as-is — capital-then-lowercase symbols, numbers for counts, parentheses for groups, and a middle dot or asterisk before a hydrate's water. The example chips fill everything in with one tap.
Read the results
The main answer sits up top in large type. A full per-element breakdown sits below it, and the exact calculation with your numbers substituted sits at the bottom.
Trust the checks
Typos, unknown elements, mismatched parentheses, and impossible values like negative mass all get flagged with a plain-English reason instead of a wrong answer. Copy any result set with one click.
One idea, three ways to use it.
Every mode above builds on the same relationship between mass, moles, and atomic weight.
Molar mass
Multiply each element's atom count by its atomic mass, then add every element together. Result comes out in grams per mole (g/mol).
Mass ↔ moles
Divide mass by molar mass to get moles, or multiply moles by molar mass to get mass back.
Percent composition
Each element's contribution to the molar mass, divided by the total, gives its share of the compound's mass.
Questions people actually ask.
The short answers — with the long ones one tap away.
What is molar mass?+
Molar mass is the mass of one mole of a substance, measured in grams per mole (g/mol). It's found by adding up the atomic masses of every atom in the chemical formula, each multiplied by how many times that atom appears.
How do you calculate molar mass from a chemical formula?+
Type the formula into the Molar mass tab — parentheses, subscripts and hydrates like CuSO4·5H2O all work. The calculator parses every atom, multiplies each element's atomic mass by its count, and adds the results together for the total molar mass and a full per-element breakdown.
How do I convert grams to moles?+
Divide mass by molar mass: n = m ÷ M. Enter the formula and the mass in the Grams to moles tab and the calculator works out the molar mass automatically, then returns the number of moles and formula units.
How do I convert moles to grams?+
Multiply moles by molar mass: m = n × M. Enter the formula and the number of moles in the Moles to grams tab and the calculator returns mass in grams, kilograms, milligrams, pounds and ounces.
What is percent composition and how is it calculated?+
Percent composition is the share of a compound's total mass contributed by each element, calculated as (count × atomic mass ÷ molar mass) × 100. The % composition tab lists this for every element, ranked from largest to smallest share.
Can this calculator handle hydrates like CuSO4·5H2O?+
Yes. Write the water molecules after a middle dot or asterisk, such as CuSO4·5H2O or CuSO4*5H2O, and the calculator adds the water's atoms into the total molar mass and breakdown automatically.
Is this tool free, and where does my data go?+
It's completely free and runs entirely in your browser — nothing you type is uploaded, logged, or sent to any server. No account, no sign-up, no limits.