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Concentration Calculator

Convert between molarity, mass concentration, percent and ppm — the four ways the same solution gets labelled.

Concentration is amount divided by volume, but "amount" can be moles, grams or a percentage, and the conversions all run through the molar mass.

g/mol
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Results
Molarity
1 mol/L
Grams per litre
Percent w/v
Parts per million
Milligrams per litre
Millimolar
Mass in that volume (g)
Moles in that volume
Reviewed September 2026. Chemistry is the same in every country: SI and laboratory units throughout.
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About concentration

How the concentration calculator works

Concentration is amount divided by volume, but "amount" can be moles, grams or a percentage, and the conversions all run through the molar mass.

Mass concentration in g/L divided by molar mass gives molarity. Percent w/v is grams per 100 mL, so 1% w/v is 10 g/L. And ppm for a dilute aqueous solution is simply mg/L, because a litre of water weighs a kilogram.

Formula: M = (g/L) / molar mass; 1% w/v = 10 g/L; 1 ppm ≈ 1 mg/L

Worked examples

InputsMolarityNote
58.44 g/L of NaCl1 mol/Lexactly 1 M
0.9% saline0.154004 mol/L0.154 M — physiological saline
10 ppm0.000171 mol/L0.171 mM

Frequently asked questions

How do I convert g/L to molarity?

Divide by the molar mass. 58.44 g/L of NaCl is exactly 1 mol/L because that is its molar mass.

What is percent w/v?

Grams of solute per 100 mL of solution. 1% w/v is 10 g/L.

Is ppm the same as mg/L?

For dilute aqueous solutions, yes, because a litre of water weighs a kilogram. For other solvents or concentrated solutions the density differs and they diverge.

What is physiological saline?

0.9% w/v NaCl — 9 g/L, or 0.154 M. It is roughly isotonic with blood.

Why so many units?

Different fields need different things. Chemistry wants moles for reactions, medicine wants mass for dosing, and environmental work wants ppm for trace amounts.

Where these figures come from

Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.