How It Works

This converter works in 4 steps.

Enter the value and unit
Type the concentration and pick its unit.
Choose the target unit
Pick M, mM, µM, g/L, mg/mL, % w/v, % w/w, ppm, or ppb.
Add molecular weight or density
Type MW in g/mol for molar conversions and ρ in g/mL for mass-fraction conversions.
Read the converted value
The converter shows the result and the chain of factors used.

The Formula

The formula links the 3 unit families through molecular weight and density.

Molar → mass g/L = M × MW

Mass/volume → percent % w/v = g/L ÷ 10

Mass fraction → mass/volume g/L = (% w/w ÷ 100) × ρ × 1,000

Aqueous ppm ppm = mg/L

M:: Molarity (mol/L)
MW:: Molecular weight (g/mol)
ρ:: Solution density (g/mL)
ppm:: Parts per million on the mg/L basis

Worked example

Physiological saline is 0.154 M NaCl (MW 58.44 g/mol). 0.154 × 58.44 = 9.0 g/L = 0.9% w/v = 9,000 ppm.

Conversion Table

The conversion table converts 6 sodium chloride (NaCl, MW 58.44 g/mol) molarities into 4 other units.

Molarity	Millimolar	g/L	% w/v	ppm (mg/L)
1 M	1,000 mM	58.44 g/L	5.844% w/v	58,440 ppm
0.5 M	500 mM	29.22 g/L	2.922% w/v	29,220 ppm
0.154 M	154 mM	9 g/L	0.9% w/v	9,000 ppm
0.1 M	100 mM	5.844 g/L	0.5844% w/v	5,844 ppm
0.01 M	10 mM	0.5844 g/L	0.05844% w/v	584.4 ppm
0.001 M	1 mM	0.05844 g/L	0.005844% w/v	58.44 ppm

What Is the Concentration Unit Converter?

The Concentration Unit Converter is a tool that converts a concentration between compatible units, including molarity, mass per volume, percent, and ppm, using molecular weight and density when the conversion needs them. The converter refuses incompatible conversions that lack the required property, such as % w/w to M without a density.

Concentration units fall into 3 families: amount per volume (M, mM), mass per volume (g/L, % w/v, mg/L ppm), and mass per mass (% w/w, mg/kg). Moving within a family needs only a prefix factor. Moving between families needs molecular weight (MW) or solution density (ρ). The converter shows which property each step uses.

Common Uses

There are 5 main uses of this converter.

Recipe translation
Users turn a % w/v recipe into molar amounts for a protocol.
Label reading
Technicians convert supplier labels from g/L to mM.
Report harmonization
Analysts report all results in one unit across methods.
Regulatory limit checks
Labs compare mg/L results with limits stated in µmol/L.
Chemistry teaching
Instructors show how MW and density bridge unit families.

Concentration Unit Converter