Concentration converter

Concentration describes how much of a substance is present in a given volume of solution. This category uses mass-per-volume measures: grams, milligrams, or micrograms per liter, and percent weight per volume (% w/v), which means grams of solute per 100 mL of solution. Water quality reports and laboratory work rely heavily on these units.

Convert between 6 concentration units. Pick any two units below; results update as you type.

From

Popular concentration conversions

About concentration units

Parts per million (ppm) and parts per billion (ppb) are ratios rather than mass-per-volume units. For dilute solutions in water, whose density is close to 1 kg/L, 1 ppm is approximately 1 mg/L and 1 ppb is approximately 1 µg/L. This approximation breaks down for concentrated solutions, liquids other than water, and gases.

For gases in air, ppm usually refers to parts by volume (ppmv), which cannot be converted to mg/m³ without knowing the gas's molar mass, temperature, and pressure.

Tips

Treat ppm as equal to mg/L only for dilute aqueous solutions such as drinking water tests.
A 1% (w/v) solution contains 1 g of solute per 100 mL, which is 10 g/L.
Molar concentrations (mol/L) require the molar mass of the substance and are not covered by these mass-based units.

All concentration units

Unit	Symbol	Value in percent (w/v)
Percent (W/v)	% w/v	1 % w/v = 1 % w/v
Micrograms per Liter	µg/L	1 µg/L = 1E-7 % w/v
Milligrams per Liter	mg/L	1 mg/L = 0.0001 % w/v
Grams per Liter	g/L	1 g/L = 0.1 % w/v
Parts per Million	ppm	1 ppm = 0.0001 % w/v
Parts per Billion	ppb	1 ppb = 1E-7 % w/v

Factors: NIST SP 811 · SI Brochure · NIST Handbook 44 — Updated October 17, 2026