Molarity Calculator
Adjust the inputs below. Results update as you type.
How it works
Molarity (M) = moles of solute / liters of solution. Moles = mass(g) / molecular weight(g/mol). To prepare a solution: moles needed = molarity × volume(L); mass needed = moles × MW. Dilution: M₁V₁ = M₂V₂. Standard solutions are prepared gravimetrically for accuracy. Temperature affects volume—volumetric glassware is calibrated at a specific temperature (usually 20°C).
Input guidance
- Confirm date/time/unit settings before comparing outputs.
- If a task has optional fields, run both with and without them to understand impact.
- Save scenario variants when making practical decisions.
The formula
Molarity (M) = moles of solute ÷ liters of solution. Moles = mass ÷ molar mass, so M = (mass ÷ molar mass) ÷ volume in liters.
Worked example
Dissolving 58.5 g of NaCl (molar mass 58.5 g/mol) in 1 liter gives 1 mole ÷ 1 L = 1 M solution.
More examples to test
- Quick-pass example: run default assumptions for a first estimate.
- Refined example: update one assumption at a time to isolate impact.
How to interpret results
Use outputs as operational estimates and pair them with local constraints, business rules, or provider requirements.
When this can be inaccurate
Utilities can miss local policy details, special-case rules, and environment-specific constraints.
Change history
- July 2026: Quality-reviewed for publication with formula checks and explanatory copy updates.
Site-wide corrections also appear on the corrections log.
Find productivity tools for everyday workflows
General recommendation, not professional advice.
Frequently asked questions
What is molarity?+
The concentration of a solution in moles of solute per liter of solution — the most common concentration unit in chemistry.
How do I prepare a specific molarity?+
Calculate the moles needed (M × volume), convert to grams using molar mass, dissolve, and dilute to the final volume.
How does dilution work?+
Use M₁V₁ = M₂V₂: the moles stay constant, so adding solvent lowers concentration in proportion to the volume increase.
Why are outputs slightly different from another tool?+
Different tools can use different rounding rules, default assumptions, and treatment of edge cases.
How can I improve estimate reliability?+
Use verified inputs from real records and re-run calculations after major assumption changes.