Parts-per Converter
Convert between Parts-per units instantly, with every unit shown side by side.
The same value in every unit
Conversion reference
One Percent expressed in each of the other Parts-per units.
| Unit | Symbol | Equivalent |
|---|---|---|
| Part per million | ppm | 10000 |
| Part per billion | ppb | 10000000 |
| Part per trillion | ppt | 10000000000 |
| Per mille | ‰ | 10 |
| Per myriad | ‱ | 100 |
About Parts-per units
Parts-per notation expresses very small proportions without long strings of zeros. One percent is 10,000 ppm, and the scale continues down through ppb and ppt — the range used for air quality, water testing and trace contamination.
How to use this converter
- Type a value into the box and choose the unit it is in.
- Pick the unit you want on the right — the result updates as you type.
- The table underneath shows the same value in every other Parts-per unit at once, so you rarely need to convert twice.
Use Swap units to reverse the direction. Values may include thousands separators.
Frequently asked questions
How accurate are the results?
Conversions use exact factors where an exact factor exists, and standard published values otherwise. Results are shown to six significant digits, which is more precision than almost any practical measurement warrants.
Is anything sent to a server?
No. The conversion runs entirely in your browser. Nothing you type is uploaded, logged or stored.
Why does the table skip some units?
A unit is left out when the value has no finite equivalent in it — for example a pace of zero, which would mean standing still forever.
Can I convert several units at once?
Yes. The table under the converter shows your value in every unit of this dimension simultaneously, so you can read off whichever you need.