Molarity Calculator
Molarity calculator (M = n/V) — enter any two of molarity, moles and volume (or use mass + molar mass) and solve for the rest. Curriculum-aligned.
Molarity Calculator
Enter any two of molarity, moles and volume — or supply mass and molar mass to get the moles. Concentration is in mol/L.
- Curriculum
- English (global) — Cambridge International + IB
- Built against
- Cambridge IGCSE Chemistry 0620 + IB Diploma (2023–2025) — The Mole Concept
- Unit system
- SI primary; US/imperial readout below
- First published
- 1 Jun 2026
- Last updated
- 1 Jun 2026
View authoritative scientific sources
- IUPAC — 2019 redefinition of the mole (Nₐ = 6.02214076×10²³)
- BIPM SI Brochure, 9th edition (2019)
- NIST — Avogadro constant
- Mole (unit) — Encyclopædia Britannica
⚠️ Educational use only — see full disclaimer
EDUCATIONAL USE DISCLAIMER
This calculator is provided for educational and reference purposes only. It is not a substitute for instruction from a qualified teacher, your prescribed textbook, or your school's official curriculum materials.
When preparing for examinations, always cross-check our calculations and notation against your current syllabus and your teacher's guidance. Syllabus conventions and accepted notation vary between curricula and may change between examination years.
If you believe any calculation, notation, or curriculum reference in this tool is inaccurate, please let us know via the feedback button. We review feedback promptly and update tools when verified corrections are needed.
RECATOOLS accepts no liability for academic, examination, professional, or research outcomes arising from use of this tool.
How to Use the Molarity Calculator
Pick your curriculum
Use the curriculum pills above to match your syllabus (Cambridge, SEAB, SPM, SBMPTN, 高考, 學測 or HKDSE). Terminology, the worked example and the whole page follow your selection.
Enter the values you know
Give any two of molarity, the number of moles and the volume. If you only know the solute mass, enter that mass and its molar mass — the calculator finds the moles first.
Read the result
The answer is in SI units — mol/L, mol, litres — plus the solute mass when a molar mass is given.
Check against your syllabus
The Tool Information block shows exactly which syllabus this is built against. Spot something off? Use the feedback button — we review every report.
Molarity, in Your Curriculum's Words
Molarity (M = moles ÷ volume)
Example: 58.5 g of sodium chloride (NaCl, molar mass = 58.5 g/mol) is dissolved in water to make 2.0 L of solution.
Given: mass = 58.5 g, Mr = 58.5 g/mol, V = 2.0 L. Using n = mass / Mr then M = n / V:
n = 58.5 / 58.5 = 1.0 mol; M = 1.0 / 2.0 = 0.50 mol/L
Molarity is a measure of concentration: the number of moles of solute per litre of solution, M = n / V. The moles n can be given directly, or worked out from mass using n = mass / molar mass. The calculator solves for whichever quantity you leave blank, and when you supply a molar mass it also reports the solute mass.
Molarity uses the volume of the final solution, not the solvent. Molar concentration has no imperial equivalent, so results are reported in SI scientific units only. All calculation happens in your browser — nothing is uploaded.
A 1 mol/L solution holds one mole of solute in every litre of solution — about 6.022 × 10²³ particles per litre.
10 Facts About Molarity
Molarity M = n / V — moles of solute per litre of solution.
One mole is 6.022 × 10²³ particles (Avogadro's number).
Since 2019 the mole is defined by fixing Nₐ = 6.02214076 × 10²³ exactly.
Molarity uses litres of solution, not solvent.
A 1 M solution has one mole of solute per litre.
Molarity changes with temperature (volume expands); molality does not.
n = mass / molar mass links grams to moles.
Concentration in mol/L is written M or mol dm⁻³.
Diluting with water lowers molarity: M₁V₁ = M₂V₂.
This calculator runs in your browser — your working stays private.
Frequently Asked Questions
- M = n / V — molarity equals the number of moles of solute divided by the volume of solution in litres. Rearranged, n = M × V and V = n / M. The calculator solves for whichever value you leave blank, and when you supply a molar mass it also works out the solute mass via mass = n × molar mass.
- Molarity in moles per litre (mol/L or M), moles in mol, volume in litres, mass in grams and molar mass in g/mol. Molar concentration has no imperial equivalent, so results are reported in SI scientific units only. You may enter mL for volume or mg/kg for mass; the tool converts to canonical units first.
- Enter the solute mass and its molar mass. The calculator finds the moles first via n = mass / molar mass, then uses M = n / V. For sodium chloride (NaCl) the molar mass is about 58.5 g/mol.
- The volume of the final solution. You dissolve the solute, then add solvent up to the desired total volume. This is why molarity differs slightly from molality, which uses the mass of solvent.
- The chemistry — M = n / V — is identical worldwide. What changes is the terminology. For example "mole" is written 摩尔 in mainland China, 莫耳 in Taiwan and 摩爾 in Hong Kong, while SPM students see "mol" and "kemolaran" — but the calculated value is the same.
- The smaller of your inputs' significant figures, capped at five, switching to scientific notation for very large or very small numbers — standard exam practice.
- Yes. 1 M = 1 mol/L = 1 mol dm⁻³ because one litre equals one cubic decimetre. Different textbooks use different notation, but the value is identical.
- The Tool Information block lists the exact syllabus for your selected curriculum (e.g. SEAB O-Level Chemistry 6092 or SPM Kimia 4541). It is a study aid, not a substitute for your official syllabus or teacher.
- Completely free, no account or usage limit. It runs entirely in your browser and collects no data.
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