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Parts Per Million (ppm) Calculator

Calculate concentration in parts per million from the mass of solute and the mass of the whole solution.

Mass of solute

Mass of solution

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How it works

ppm = (mass of solute ÷ mass of solution) × 1,000,000

Parts per million is a mass ratio scaled by a million: 1 ppm means 1 gram of solute in 1,000,000 grams (1 tonne) of solution, equivalent to 1 mg per kg. For dilute water solutions where 1 L weighs about 1 kg, 1 ppm is also roughly 1 mg per litre. It is the standard unit for trace contaminants, water hardness and air quality.

Worked example

Dissolving 0.5 g of a mineral in 1000 g of water gives (0.5 ÷ 1000) × 1,000,000 = 500 ppm, i.e. 500 mg of mineral per kilogram of solution.

Sources: Parts-per notation — Wikipedia

Frequently asked questions

Is 1 ppm the same as 1 mg/L?

For dilute water solutions, yes — because 1 L of water weighs about 1 kg and 1 ppm equals 1 mg per kg. For denser solutions or non-aqueous solvents the density correction matters.

How do ppm, ppb and percent relate?

1% = 10,000 ppm and 1 ppm = 1000 ppb. So to convert ppm to percent divide by 10,000, and to convert ppm to ppb multiply by 1000.

What counts as the mass of solution?

The total mass of solute plus solvent. In very dilute cases the solvent mass alone is a close approximation, but for accuracy add the solute mass in too.

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Educational estimate. Check the formula, units and significant figures for your exact case.