Parts-Per Converter
Convert a concentration between ppm, ppb, ppt and percent - handy for water tests, air quality readings and lab measurements.
About the Parts-Per Converter
This tool converts a concentration between parts per million (ppm), parts per billion (ppb), parts per trillion (ppt) and percent. These are dimensionless ratios that express how much of one substance is present in a whole, common in water testing, air quality, chemistry and environmental reporting.
How to use it
- Enter the value you have into its field, for example a water reading in ppm.
- Read the equivalent as a percent or in ppb and ppt.
- Convert in either direction when a report or limit uses a different scale.
The relationships are simple powers of ten: 1 percent is 10,000 ppm, 1 ppm is 1000 ppb and 1 ppb is 1000 ppt. So a 0.5 percent solution is 5000 ppm. One caveat: ppm can be defined by mass, by volume or by moles, and this converter treats the values as plain ratios, so make sure you are comparing the same basis (for example mg/L is often treated as ppm by mass in dilute water). All conversions run in your browser and nothing you type is uploaded.
Frequently asked questions
How do I convert ppm to percent?
Divide ppm by 10,000. So 2500 ppm equals 0.25 percent, and 1 percent equals 10,000 ppm.
How many ppb are in 1 ppm?
One part per million equals 1000 parts per billion. Likewise, one ppb equals 1000 ppt, since each step is a factor of 1000.
Is ppm by mass the same as ppm by volume?
Not always. ppm can be defined by mass, volume or moles, and the values differ unless the basis is the same. For dilute water solutions, 1 mg/L is commonly treated as 1 ppm by mass.
What is parts per million used for?
It expresses very small concentrations, such as contaminants in drinking water, CO2 in air or trace chemicals in a sample, where a percent would be an awkwardly small fraction.