mg/L to PPM Converter
Convert a concentration in milligrams per liter (mg/L) to parts per million (ppm) and back. For dilute aqueous solutions the density is about 1 g/mL, so mg/L and ppm are numerically equal. Adjust the density for other solvents.
Convert
Concentration
mg/L
Solute density
mg/L vs PPM
Parts per million is a mass ratio: milligrams of solute per kilogram of solution. Milligrams per liter is a mass-per-volume concentration.
They are linked by the solution's density. Dividing mg/L by the density in g/mL converts to ppm. When the density is 1 g/mL — true for dilute water solutions — the two values are identical.
Formula
ppm = concentration (mg/L) ÷ density (g/mL)
Example: Convert 50 mg/L in water (density 1 g/mL) to ppm:
50 ÷ 1 = 50 ppm