PPB to PPM converter
Water and air quality reports give trace amounts in ppb, while many meters and specs use ppm. This converter moves between them exactly.
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How to use it
- Enter concentration.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
1 ppm = 1000 ppb, so ppm = ppb ÷ 1000. And 1 ppb = 0.0000001% = 0.000000001, one part in a billion.
Example
Inputs: Concentration = 50 ppb. Result: Parts per million: 0.05 ppm; Percentage: 0.000005%; Decimal: 0.00000005.
Limits and caveats
- This is a pure ratio on the same basis: ppb by volume gives ppm by volume.
- Treating 1 ppb as 1 µg/L is an approximation for dilute water only and does not hold for gases.
Questions about this tool
How many ppb are in 1 ppm?
1 ppm equals 1000 ppb, so divide by 1000 to go from ppb to ppm.
What is 10 ppb of arsenic in drinking water in ppm?
It is 0.01 ppm, which is the World Health Organization guideline value for arsenic in drinking water, 10 µg/L.
Is ppb the same as micrograms per litre?
Roughly, in dilute water only, because a litre of it weighs about a kilogram, so 1 ppb is close to 1 µg/L. For gases the relationship is different.