PPM Calculator (Parts Per Million)
Enter the amount of the part and the whole (in the same units) to get the concentration in ppm.
Use the same units for both (e.g. grams and grams).
Parts per million (ppm) expresses a small concentration as the number of parts of a substance per million parts of the whole. Divide the part by the whole and multiply by 1,000,000. In water, 1 ppm also equals about 1 milligram per litre. For example, 2 grams in 10,000 grams is 200 ppm.
How to Use This Calculator
Enter the amount of the substance (the part) and the total amount (the whole), using the same units for both so they cancel. The calculator returns the concentration in parts per million, along with the equivalent percentage.
PPM is used for very dilute concentrations where a percentage would be an awkward small decimal — water hardness, pool chemicals, air pollutants and trace nutrients are all commonly measured in ppm.
How the Calculation Works
A part per million is one unit of substance in a million units of total, so you divide the part by the whole to get the fraction, then multiply by one million to scale it. It is just a percentage taken to a finer resolution — a percent is parts per hundred, ppm is parts per million.
For dilute water solutions, one ppm is essentially one milligram per litre, because a litre of water weighs about a million milligrams. That equivalence makes ppm and mg/L interchangeable in water chemistry.
ppm = (part ÷ whole) × 1,000,000
Worked Example
Dissolve 2 grams of a substance in 10,000 grams of solution. The fraction is 2 ÷ 10,000 = 0.0002, and multiplying by 1,000,000 gives 200 ppm.
As a percentage that is 0.02% — the same concentration, which shows why ppm is the clearer unit for small amounts.
Assumptions and Limitations
- Part and whole must be in the same units
- 1 ppm ≈ 1 mg/L only for dilute water-based solutions
- ppm is a ratio, so it is unitless
- For extremely small amounts, ppb (parts per billion) may be clearer
Who Uses a PPM Calculator
Chemistry and environmental-science students, along with water and pool testers, use this to convert a part-to-whole ratio into parts per million. Run it for lab work, water-quality checks, or dilution problems. Enter the amounts to get the concentration in ppm.
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Open calculator →Frequently Asked Questions
How do you calculate ppm?
Divide the part by the whole (in the same units) and multiply by 1,000,000. So 2 g in 10,000 g is (2 ÷ 10,000) × 1,000,000 = 200 ppm.
Is 1 ppm the same as 1 mg/L?
For dilute water solutions, essentially yes, because a litre of water is about a million milligrams. In water chemistry ppm and mg/L are used interchangeably.
How do ppm and percent relate?
Percent is parts per hundred; ppm is parts per million. To convert, 1% = 10,000 ppm, and to go from ppm to percent divide by 10,000.
What is ppm used for?
Very dilute concentrations — water hardness, chlorine in pools, dissolved solids, air pollutants, and trace nutrients — where a percentage would be an inconveniently tiny number.
What is ppb?
Parts per billion — a thousand times finer than ppm — used for extremely small concentrations such as some contaminants. 1 ppm equals 1,000 ppb.
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