How ratio unit conversion works
Percent, permille, ppm, and the plain multiplier (×) all express the same idea — a fraction of a whole — at different scales. The value is first converted to the base ratio (×1), then into the target unit.
- factor_from — value of 1 unit of the source unit relative to ×1 (0.01 for %, 0.001 for ‰, 0.000001 for ppm)
- factor_to — same factor for the target unit
Common values
| Value (ppm) | Result |
|---|---|
| 42 ppm | 0.0042 % |
| 110 ppm | 0.011 % |
| 210 ppm | 0.021 % |
| 420 ppm | 0.042 % |
| 630 ppm | 0.063 % |
| 840 ppm | 0.084 % |
| 1,300 ppm | 0.13 % |
| 2,100 ppm | 0.21 % |
| 4,200 ppm | 0.42 % |
More detail
When to use which unit
Percent (%) fits everyday ratios. Permille (‰) shows up where more precision matters, like blood alcohol concentration or birth rates. Ppm covers ratios too small for percent to show cleanly, like air pollution or semiconductor impurities. The multiplier (×) just states how many times the original value — 100% equals exactly 1×.
Common conversions
1% = 10‰ = 10,000 ppm. 0.1% = 1,000 ppm. 1‰ = 1,000 ppm. Atmospheric CO2 at roughly 420 ppm works out to 0.042% — small in percent terms but significant at ppm scale.
Watch the zeros. Percent and ppm differ by a factor of 10,000, so it's easy to misplace a decimal. After converting, sanity-check the result's order of magnitude against the table above.
Frequently asked questions
How many ppm is 1%?
1% = 0.01 = 10,000 ppm. Set Value to 1, From to Percent, and To to ppm above to see it computed live.
What's the difference between permille (‰) and percent (%)?
Permille is parts per thousand, ten times finer than percent's parts per hundred — 1% = 10‰. It's used where percent isn't precise enough, such as blood alcohol concentration.
When is ppm used instead of percent?
Ppm (parts per million) covers ratios too small to show cleanly in percent, like air pollution or semiconductor impurities. Atmospheric CO2 at about 420 ppm — this tool's default — equals 0.042%.
What percent is 2 times (2×)?
2× equals 200%. The multiplier unit states how many times the original value, and 100% equals exactly 1×.