Classic tool
Molecular Weight Calculator
Calculate molecular weight and molar mass from a chemical formula, including parentheses, hydrates and repeated groups.
Use this molecular weight calculator to find the molar mass of compounds, salts, oxides, acids and hydrates without adding every atomic mass by hand. It reads the chemical formula and returns the total in g/mol.
Enter formulas such as H2O, NaCl, Ca(OH)2, Fe2(SO4)3 or CuSO4·5H2O. The tool handles multipliers, repeated groups and common hydrate notation, then shows a clear element-by-element breakdown.
It is useful for homework, lab prep, solution planning, stoichiometry checks and quick comparisons before converting grams to moles or reviewing reaction inputs.
Use clear inputs to get a more useful result.
How the calculation works
The calculator parses each element symbol, applies the multipliers for groups inside parentheses, brackets or braces, and adds the mass contribution of every atom. The final result is shown as an estimated molar mass in grams per mole.
Formula tips
- Keep element symbols case-sensitive, such as NaCl, Fe2O3 and Mg(OH)2.
- Hydrates can be written with a dot, such as CuSO4·5H2O.
- Use the breakdown panel to verify where most of the mass comes from before moving on to stoichiometry or solution calculations.
How to use Molecular Weight Calculator
Open the tool, fill in the fields with the data you already have and generate the result step by step. If you want to compare scenarios, change one field at a time so it is easier to understand the impact of each value.
When Molecular Weight Calculator is useful
The goal here is simple: Calculate molecular weight and molar mass from a chemical formula, including parentheses, hydrates and repeated groups. It works well for quick checks, planning, study and review before you move to a final decision or document.
What to review before using the result
Check units, labels, numbers, timing and any context that can change the meaning of the output. If the result will be used in a quote, technical task, published page or report, finish with a manual review.
Frequently asked questions
What should I prepare before using the tool?
Keep the key values, labels and units ready before filling in the fields. Cleaner inputs make the final result easier to review and compare.
Can I test different scenarios on the same page?
Yes. The safest approach is to change one field at a time, compare the outputs and note which value actually changes the final answer.
Is the result ready to use without checking it?
It is better to treat it as support. Review the output once more before using it in a quote, document, spreadsheet, technical task or published page.