Molar Mass Calculator
Enter a classroom chemical formula to calculate molar mass in grams per mole. The calculator breaks the formula into elements, atom counts, mass contributions, and percent-by-mass rows.
Main unit
g/mol
Supports
Parentheses + hydrates
Reference
Atomic weights
Live calculator
Chemical formula input
Supports common classroom element symbols, parentheses, and hydrates such as CuSO4.5H2O.
Molar mass
74.092 g/mol
Formula
Ca(OH)2
Atoms
5
Elements
3
| Element | Count | Mass | % mass |
|---|---|---|---|
| CaCalcium | 1 | 40.078 | 54.09% |
| HHydrogen | 2 | 2.016 | 2.72% |
| OOxygen | 2 | 31.998 | 43.19% |
Turn formulas into auditable molar-mass rows
Element breakdowns
See each supported element, count, atomic weight, mass contribution, and percent-by-mass share.
Hydrate examples
Check formulas such as CuSO4.5H2O without manually expanding every water molecule first.
Percent composition
Compare how much each element contributes to the compound's total molar mass.
Molar mass formulas used on this page
Molar mass is the sum of each element count multiplied by its atomic weight. Percent composition compares each element contribution with the total.
Working formulas
Molar mass
M = sum(n_i x atomic weight_i)
Multiply each element count by its atomic weight, then add all contributions.
Mass contribution
element mass = n_i x atomic weight_i
The contribution is shown in grams per mole for each element row.
Percent by mass
percent = element mass / total molar mass x 100
Use this to compare formula composition by mass instead of atom count.
Symbols
- M - molar mass
- The mass of one mole of formula units, shown in grams per mole.
- n_i - element count
- The number of atoms of a given element after parentheses and hydrates are expanded.
- atomic weight_i - relative atomic weight
- The source-backed atomic-weight value used for the element.
- percent - percent by mass
- The share of total molar mass contributed by one element.
Chemistry results with the formula audit visible
Formula parsing you can check
- Element rows make it clear which symbols were recognized and how many atoms were counted.
- Parentheses and hydrate notation are expanded before the mass table is calculated.
- The percent-by-mass column supports composition questions without a second calculation.
- Copy and print controls let users keep the parsed result with homework notes.
Source-aware classroom scope
- The guide links explain that atomic weights are reference values and may be rounded for classroom work.
- FAQ copy distinguishes molar mass, molecular mass, empirical formulas, and percent composition.
- Related tools connect molar mass to dilution and pH where concentration units are used.
- The page avoids medical, dosing, and laboratory safety recommendations; it is an educational calculator.
Molar-mass support for chemistry study
Students
Check formula parsing before using molar mass in stoichiometry or percent-composition practice.
Teachers
Create examples that show each element contribution instead of only the final grams-per-mole value.
Science reviewers
Audit common formulas, hydrates, and rounded atomic-weight assumptions for educational notes.
How it works in three quick steps.
Enter the formula
Type a formula such as H2O, Ca(OH)2, or CuSO4.5H2O using standard element capitalization.
Review element counts
Check the parsed table to confirm each element symbol, atom count, and atomic weight contribution.
Use the molar mass
Use the grams-per-mole result for classroom stoichiometry, percent composition, or mole-to-mass checks.
Save or print a molar mass result
Copy the mass summary
Copy the formula, total molar mass, and atom count for notes or classroom answer checks.
Print the formula table
Print the result panel, element table, formulas, FAQ answers, and related chemistry tools.
Compare examples
Switch between common formulas to compare atom count and percent-by-mass changes.
Why molar mass needs a visible element table
Molar mass is a foundation calculation in chemistry because it connects a written formula with grams per mole. The answer is easy to misuse if the formula was parsed incorrectly. A missing parenthesis, lower-case element error, or hydrate multiplier can change the result before the arithmetic even begins. Toolarithm's Molar Mass Calculator keeps the parsing step visible by showing each element, count, atomic weight, mass contribution, and percent-by-mass share.
The content is intentionally educational. The calculator uses a practical common-element set and rounded atomic weights so students can compare results with classroom reference tables. It links to the concentration guide for users who need to move from grams per mole into molarity, dilutions, or pH relationships. The page avoids lab-safety instructions and medical uses because those contexts require validated procedures beyond a web calculator.
Keep building