Meaning & use
ppm
Last updated
Meanings
abbreviationchemistry
Parts per million: a unit showing how many units of a substance are present in every million units of a mixture, used for very small amounts.
Grammar: Follows a number and does not take a s: 5 ppm, not 5 ppms.
Patterns
- something ppm of something
The test found lead at 3 ppm in the water sample.
Carbon dioxide in the air passed 420 ppm this year.
The pool needs about 2 ppm of chlorine to stay safe.
abbreviationcomputing
Pages per minute: a measure of how fast a printer or copier produces pages.
Grammar: Written after a number: a 30 ppm printer.
The office bought a laser printer rated at 40 ppm.
At only 8 ppm, the old inkjet was too slow for large reports.
Common combinations
- parts per million
- Fluoride is measured in parts per million.
- measured in ppm
- Soil salt levels are measured in ppm.
- ppm level
- The ppm level of ammonia in the tank rose overnight.
- below a limit of ppm
- The factory kept emissions below 50 ppm.
Synonyms and how they differ
- milligrams per liter
- For water this is nearly the same number as ppm, but it names the exact units instead of using a ratio.
- parts per billion
- It is a thousand times smaller (ppb), so it suits trace amounts that ppm is too coarse to describe.
Word family
- ppb abbreviation
- parts per billion
- percent noun
- parts per hundred
- concentration noun
- the amount of a substance in a mixture
Commonly confused: ppm or ppb?
ppm vs ppb
Ppb means parts per billion, which is a thousand times smaller than ppm, so mixing them gives a hugely wrong figure.
Practice
A lab report says the water contains 5 ppm of nitrate. What does ppm tell you?
Choose one answer.
Ppm means parts per million, a measure of concentration. Percent would mean parts per hundred, which is a much larger unit.
Make it your own
Write a sentence using “ppm”, then check it and compare it with the examples above.