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ppm to ppb Conversion

Parts per million and parts per billion both describe a very small share of a whole, and one part per million is the same share as 1000 parts per billion. Enter a ppm value and press Convert to see the matching figure in ppb.

What ppm and ppb describe

A part per million is one unit out of a million, or 1/1,000,000 of the whole. A part per billion is one unit out of a billion, or 1/1,000,000,000 of the whole. Because a billion is a thousand times bigger than a million, the same quantity written in ppb always comes out a thousand times larger as a number than it does in ppm.

Both units are ratios rather than physical measures, so moving between them changes only the scale the share is written on, not the share itself. That is why a single multiplication is all the conversion takes.

ppm to ppb formula

ppb = ppm x 1000. Multiply the number of parts per million by 1000 to get the number of parts per billion. The factor 1000 is exact here: a part per million is 1/10^6 and a part per billion is 1/10^9, and those two definitions differ by precisely a thousandfold.

For example, 7 ppm works out to 7 x 1000 = 7000 ppb. To go the other way and turn a ppb figure back into ppm, divide by 1000 instead.