PPM Calculator
This ppm calculator converts parts per million. Example: 250 ppm is 0.025%, 250,000 ppb and, at a density of 1 kg/L, exactly 250 mg/L.
Source: Wikipedia – Parts-per notation (1 ppm = 10⁻⁶ = 1 mg/kg). Updated: .
How it is calculated
ppm stands for “parts per million” and means one millionth: 1 ppm = 0.0001% = 1 mg per kilogram. It is used for very small fractions, such as trace substances in water, soil or food. ppb (parts per billion) is a thousandth of that.
Conversions
Percent = ppm / 10,000, and conversely ppm = percent · 10,000. 1 ppm equals 1000 ppb and 1 mg/kg. From substance mass and sample mass, ppm = mg of substance / kg of sample. For solutions mg/L = ppm · density in kg/L; for dilute aqueous solutions with a density of about 1 kg/L, mg/L and ppm are practically equal.
Worked example
250 ppm is 250 / 10,000 = 0.025%, and likewise 250,000 ppb. At a density of 1 kg/L that corresponds to 250 mg/L. 5 mg of a substance in 2 kg of sample gives 5 / 2 = 2.5 ppm. And 0.5% is 0.5 · 10,000 = 5000 ppm.
- For liquids with a density other than 1 kg/L, mg/L and ppm differ; that is why the calculator asks for the density.
- For gases, ppm usually means a volume fraction (ppmv), not a mass fraction.
- A fraction of 1,000,000 ppm equals 100%.
Frequently asked questions
How do you convert ppm to percent?
Divide by 10,000: 250 ppm / 10,000 = 0.025%. Conversely, multiply percent by 10,000.
Are ppm and mg/L the same?
Only approximately, namely at a density of 1 kg/L, as with dilute aqueous solutions. In general mg/L = ppm · density in kg/L.
What is the difference between ppm and ppb?
ppm is one millionth, ppb one billionth. So 1 ppm is 1000 ppb.
Sources and legal basis
- Wikipedia – Parts-per notation (1 ppm = 10⁻⁶ = 1 mg/kg)
- NIST SP 811 – Guide for the Use of the International System of Units (Kap. 7.10: ppm ist kein SI-Symbol, Dimension angeben)
As of: · Editorial policy
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