Convert Per mille to Per cent
1 per mille is 0.1 %. One per mille is exactly 0.1 per cent.
One per mille is 0.1 per cent. To convert per mille to per cent, multiply by 0.1; to go the other way, divide by 0.1 or multiply by 10. The factor is exact rather than rounded: it follows from NIST SP 811 §7.10.3. Parts per thousand, written ‰.
Factor checked against the defining standard · How we check
- Per mille × 0.1
1 * 0.10.1 %
1 per mille in every concentration unit
| Unit | Value | Exact factor |
|---|---|---|
| per cent | 0.1 % | × 0.1 |
| per mille (as entered) | 1 ‰ | — |
| parts per million | 1,000 ppm | × 1,000 |
| parts per billion | 1,000,000 ppb | × 1,000,000 |
| parts per trillion | 1,000,000,000 ppt | × 1,000,000,000 |
Factors are entered by hand from NIST SP 811 §7.10.3 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert per mille to per cent? The converter and the working
- 1.Take the measurement in per mille.
- 2.Multiply by 0.1 — that is how many per cent fit in one per mille.
- 3.To go back the other way, divide by 0.1, or multiply by 10.
Worked example: 25 per mille to per cent
- Formula
- ‰ × 0.1 = %
- Arithmetic
- 25 × 0.1 = 2.5 %
- Answer
- 25 ‰ = 2.5 %
The factor is exact, so this figure is exact too — only the display is rounded.
Per mille to per cent conversion table
| Per mille | Per cent |
|---|---|
| 1 ‰ | 0.1 % |
| 2 ‰ | 0.2 % |
| 3 ‰ | 0.3 % |
| 4 ‰ | 0.4 % |
| 5 ‰ | 0.5 % |
| 6 ‰ | 0.6 % |
| 7 ‰ | 0.7 % |
| 8 ‰ | 0.8 % |
| 9 ‰ | 0.9 % |
| 10 ‰ | 1 % |
| 12 ‰ | 1.2 % |
| 15 ‰ | 1.5 % |
| 20 ‰ | 2 % |
| 25 ‰ | 2.5 % |
| 50 ‰ | 5 % |
| 100 ‰ | 10 % |
| 200 ‰ | 20 % |
| 300 ‰ | 30 % |
| 500 ‰ | 50 % |
| 1000 ‰ | 100 % |
| 2000 ‰ | 200 % |
| 5000 ‰ | 500 % |
| 10000 ‰ | 1,000 % |
What is a per mille?
Parts per thousand, written ‰. Used for blood alcohol in most of Europe, for salinity, and for slope in rail engineering.
What is a per cent?
Parts per hundred. One per cent is 10,000 ppm, which is the conversion people reach for when a water report and a lab result are in different units.
How many per cent are in a per mille?
One per mille is 0.1 per cent, exactly. Going the other way, one per cent is 10 per mille. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every concentration unit here
The whole group — 5 units with their symbols and the size of each one in part per millions — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a per mille.
Source: NIST SP 811 §7.10.3 — why ppm, ppb and ppt should be avoided and what they mean
Cite this page
- APA
- Rule Calculator. (2026). Convert Per mille to per cent. Rule Calculator. https://rulecalculators.com/convert/permille-to-percent
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- "Convert Per mille to per cent." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/permille-to-percent.
- Chicago
- Rule Calculator. "Convert Per mille to per cent." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/permille-to-percent.
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Questions people actually ask
- How many per cent are in a per mille?
- 0.1. Parts per hundred. One per cent is 10,000 ppm, which is the conversion people reach for when a water report and a lab result are in different units.
- How do I convert per cent back to per mille?
- Divide by 0.1, or multiply by 10 — they are the same operation.
Other concentration conversions
Per cent to per mille — the same conversion the other way.