PPM Calculator
Calculate parts per million from the amount of a substance and the total amount, or convert between ppm, ppb, percent and mg/L.
PPM formula
ppm = amount of substance ÷ total amount × 1,000,000
Both amounts must use the same unit. Parts per million is common for water quality, air pollutants and nutrient solutions.
Worked example
0.5 g of salt in 2,000 g of solution is 0.5 ÷ 2,000 × 1,000,000 = 250 ppm, which is 0.025%.
Conversions
| From | To | How |
|---|---|---|
| ppm | % | divide by 10,000 |
| % | ppm | multiply by 10,000 |
| ppm | ppb | multiply by 1,000 |
| ppm | mg/L | about equal for dilute water solutions |
The ppm ≈ mg/L shortcut only holds for dilute solutions in water at room temperature, where 1 L weighs about 1 kg.
Frequently asked questions
Is ppm the same as mg/L?
For dilute solutions in water, approximately yes, because 1 liter of water has a mass of about 1 kilogram.
How do I convert percent to ppm?
Multiply by 10,000. 0.5% is 5,000 ppm.
What is ppb?
Parts per billion, 1,000 times smaller than ppm.
Does ppm use mass or volume?
Either, as long as both amounts use the same basis. Gases are often given by volume (ppmv).
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