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PPM Calculator

Enter a concentration and its unit to see it as ppm, ppb, percent by mass, mg/L and µg/L. The density turns per-litre units into mass fractions.

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Formula

  • ppm = mass of solute ÷ mass of mixture × 1,000,000
  • ppb = ppm × 1,000 and ppt = ppm × 1,000,000
  • percent = ppm ÷ 10,000
  • mg/L = ppm × density (g/mL), so ppm = mg/L ÷ density
  • µg/L = mg/L × 1,000 and g/L = mg/L ÷ 1,000

mg/kg is identical to ppm. The density only matters for per-litre units; the default of 1 g/mL suits dilute water solutions.

Worked example

5 mg/L in water (density 1 g/mL):

  • ppm = 5 ÷ 1 = 5 ppm
  • ppb = 5 × 1,000 = 5,000 ppb
  • percent = 5 ÷ 10,000 = 0.0005 %

With a density of 1.2 g/mL, 12 mg/L is 12 ÷ 1.2 = 10 ppm. A concentration above 100 percent (1,000,000 ppm) by mass is impossible and is rejected.

Frequently asked questions

How do I convert ppm to percent?

Divide ppm by 10,000. One percent is one part in 100, which is 10,000 parts per million, so 2,500 ppm is 0.25 percent.

Is 1 ppm the same as 1 mg/L?

In dilute water solutions, yes, because 1 L of water weighs about 1 kg and 1 mg in 1 kg is one part per million. For other liquids use mg/L = ppm × density in g/mL. At a density of 1.2 g/mL, 12 mg/L is 12 ÷ 1.2 = 10 ppm.

How many ppb are in a ppm?

1 ppm is 1,000 ppb, and 1 ppb is 1,000 ppt. So 5 mg/L in water is 5 ppm, which is 5,000 ppb or 5,000 µg/L.

Does ppm mean mass or volume?

This calculator uses mass fractions (mg of solute per kg of mixture), which is the usual meaning for liquids and solids. For gases ppm is often by volume (ppmv) or by mole, and those do not convert with the density used here.

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