PPM Calculator AU
Convert a part and a total into parts per million (ppm), percent, parts per billion and a ratio.
How it works
Enter the part (the amount of the substance) and the total it is contained in. The calculator returns parts per million, the equivalent percent, parts per billion, and the figure as a simple ratio.
Frequently asked questions
What does ppm mean?
Parts per million — the number of parts of a substance per one million parts of the whole. 1 ppm equals 0.0001%.
How do I convert ppm to percent?
Divide the ppm value by 10,000. So 250 ppm is 0.025%.
How do I convert percent to ppm?
Multiply the percent by 10,000. So 0.5% is 5,000 ppm.
Is 1 ppm the same as 1 mg/L?
In dilute water solutions, yes — they are practically equal because a litre of water weighs about one million milligrams.
What is ppb?
Parts per billion — one thousand times smaller than ppm. 1 ppm equals 1,000 ppb.
Where is ppm used?
In water quality, air pollution, pool maintenance and chemistry, wherever very small concentrations need to be measured.
What parts per million means
Parts per million (ppm) expresses a very small concentration: how many parts of a substance there are in one million parts of the whole. 1 ppm = 1⁄1,000,000 = 0.0001%. The calculator converts between ppm, percent and fractions for you.
ppm and percent
Because 1% is 10,000 ppm, converting is easy: divide ppm by 10,000 to get percent, or multiply percent by 10,000 to get ppm. So 250 ppm is 250 ÷ 10,000 = 0.025%, and 0.5% is 5,000 ppm.
ppm in water and air
For dilute water solutions, 1 ppm is very close to 1 milligram per litre (mg/L), because a litre of water weighs about a million milligrams. This is why water-quality reports for hardness, chlorine or contaminants are given in ppm or mg/L interchangeably.
ppm is used wherever tiny concentrations matter — air quality, drinking water, pool chemistry and laboratory work — and its cousin ppb (parts per billion) handles concentrations a thousand times smaller still.
Results are estimates for general guidance in Australia and may not reflect the latest local rates, fees or rules. Check official sources before making decisions.