Percent and PPM Converter
Convert a plain ratio, percent, per mille, parts per million and parts per billion with the factor behind each answer.
1 ppm = 1 × 10⁻⁴ %
Common conversions
- 1 ppm = 1 × 10⁻⁴ %
- 1 % = 10,000 ppm
- 1 ppb = 0.001 ppm
- 1 ppm = 1,000 ppb
- 1 ratio = 100 %
- 1 % = 0.01 ratio
Percent and ppm
One percent is one part in 100 and one ppm is one part in 1,000,000, so 1 % = 10,000 ppm and 100 ppm = 0.01 %.
Where ppm appears
Crystal accuracy, resistor temperature coefficients (ppm/°C), sensor drift and gas concentrations are quoted in ppm. A 50 ppm/°C resistor changes by 0.005 % per degree.
Mass, volume and mole ppm
The conversion here is for a pure ratio. A gas concentration in ppm by volume is not the same as mg/kg by mass, which also depends on the gas.
Unit factors
Every unit in terms of the base unit shown. To convert, multiply by the factor of the unit you have and divide by the factor of the unit you want.
| Unit | Equals | What it is |
|---|---|---|
| ratio | 1 ratio | A plain ratio or fraction, where 1 means the whole. 0.5 is 50 %. |
| % | 0.01 ratio | Percent, parts per hundred. |
| ‰ | 0.001 ratio | Per mille, parts per thousand. |
| ppm | 1 × 10⁻⁶ ratio | Parts per million. Contaminant, drift and tolerance figures. |
| ppb | 1 × 10⁻⁹ ratio | Parts per billion. |
Conversion pages
Frequently asked questions
What is the formula to convert ppm to %?
% = ppm × 1 × 10⁻⁴. For example, 250 ppm is 0.025 %.
How do I convert % back to ppm?
ppm = % × 10,000. The Swap button above reverses the direction for any pair of units.
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