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Parts per Million (ppm)


Updated June 27, 2014

Definition: “Parts per million” – usually abbreviated as “ppm” – means “out of a million.”

"Parts per Million" is a way to quantify very low concentrations of substances. For example, 1 ppm is equivalent to 1 milligram of something per liter of liquid (abbreviated as mg/L) or 1 milligram of something per kilogram of solid substance (abbreviated as mg/kg).

In terms of percents, 1 ppm equals 0.0001 percent.

If a product has 20 ppm of gluten, that would mean it contains 20 milligrams of gluten (about 7 thousandths of an ounce, or 0.0007 ounces) per kilogram (2.2 pounds) or per liter.

Also Known As: ppm

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