Convert Per cent to Per mille
1 per cent is 10 ‰. One per cent is exactly 10 per mille.
One per cent is 10 per mille. To convert per cent to per mille, multiply by 10; to go the other way, divide by 10 or multiply by 0.1. The factor is exact rather than rounded: it follows from NIST SP 811 §7.10.3. Parts per hundred.
Factor checked against the defining standard · How we check
- Per cent × 10
1 * 1010 ‰
1 per cent in every concentration unit
| Unit | Value | Exact factor |
|---|---|---|
| per cent (as entered) | 1 % | — |
| per mille | 10 ‰ | × 10 |
| parts per million | 10,000 ppm | × 10,000 |
| parts per billion | 10,000,000 ppb | × 10,000,000 |
| parts per trillion | 10,000,000,000 ppt | × 10,000,000,000 |
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 cent to per mille? The converter and the working
- 1.Take the measurement in per cent.
- 2.Multiply by 10 — that is how many per mille fit in one per cent.
- 3.To go back the other way, divide by 10, or multiply by 0.1.
Worked example: 25 per cent to per mille
- Formula
- % × 10 = ‰
- Arithmetic
- 25 × 10 = 250 ‰
- Answer
- 25 % = 250 ‰
The factor is exact, so this figure is exact too — only the display is rounded.
Per cent to per mille conversion table
| Per cent | Per mille |
|---|---|
| 1 % | 10 ‰ |
| 2 % | 20 ‰ |
| 3 % | 30 ‰ |
| 4 % | 40 ‰ |
| 5 % | 50 ‰ |
| 6 % | 60 ‰ |
| 7 % | 70 ‰ |
| 8 % | 80 ‰ |
| 9 % | 90 ‰ |
| 10 % | 100 ‰ |
| 12 % | 120 ‰ |
| 15 % | 150 ‰ |
| 20 % | 200 ‰ |
| 25 % | 250 ‰ |
| 50 % | 500 ‰ |
| 100 % | 1,000 ‰ |
| 200 % | 2,000 ‰ |
| 300 % | 3,000 ‰ |
| 500 % | 5,000 ‰ |
| 1000 % | 10,000 ‰ |
| 2000 % | 20,000 ‰ |
| 5000 % | 50,000 ‰ |
| 10000 % | 100,000 ‰ |
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.
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.
How many per mille are in a per cent?
One per cent is 10 per mille, exactly. Going the other way, one per mille is 0.1 per cent. 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 cent.
Source: NIST SP 811 §7.10.3 — why ppm, ppb and ppt should be avoided and what they mean
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- APA
- Rule Calculator. (2026). Convert Per cent to per mille. Rule Calculator. https://rulecalculators.com/convert/percent-to-permille
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- "Convert Per cent to per mille." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/percent-to-permille.
- Chicago
- Rule Calculator. "Convert Per cent to per mille." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/percent-to-permille.
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Questions people actually ask
- How many per mille are in a per cent?
- 10. Parts per thousand, written ‰. Used for blood alcohol in most of Europe, for salinity, and for slope in rail engineering.
- How do I convert per mille back to per cent?
- Divide by 10, or multiply by 0.1 — they are the same operation.
Other concentration conversions
Per mille to per cent — the same conversion the other way.