Calculator tool
How this calculator works
Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.
What This Calculator Does
This calculator adds the atomic masses in a chemical formula to estimate molecular weight, often called molar mass in grams per mole.
A Simple Example
Water is written as H2O. That means 2 hydrogen atoms and 1 oxygen atom:
Why the Formula Must Be Read Carefully
Subscripts are counts, not decoration. CO and CO2 are different substances with different masses because one has one oxygen atom and the other has two. Parentheses also matter because they can multiply whole groups of atoms.
How to Use the Result
Molar mass helps convert between grams and moles in chemistry calculations. Before using the answer, check capitalization, subscripts, and parentheses so the formula describes the intended compound.
Frequently asked questions
Is molecular weight the same as molar mass?
They are closely related. Molecular weight is a relative mass, while molar mass is usually reported in grams per mole for practical calculations.
Why do subscripts matter?
A subscript tells how many atoms of that element are present. H2O and H2O2 are different compounds with different masses.
Can I use the result to convert grams to moles?
Yes. Divide sample mass in grams by molar mass in grams per mole to estimate the number of moles.
What should I check in a chemical formula?
Check capitalization, subscripts, and parentheses. A small notation error can describe a completely different compound.
