Convert Parts per billion to Per mille
1 part per billion is 0.000001 ‰. One part per billion is exactly 0.000001 per mille.
One part per billion is 1.0000 × 10^-6 per mille. To convert parts per billion to per mille, multiply by 1.0000 × 10^-6; to go the other way, divide by 1.0000 × 10^-6 or multiply by 1000000. The relation is exact but the figure is not: it is a rounding of a number that does not terminate, and it follows from NIST SP 811 §7.10.3. One in a thousand million, on the short scale.
Factor checked against the defining standard · How we check
- Parts per billion × 1.0000 × 10^-6
1 * 0.0000010 ‰
1 part per billion in every concentration unit
| Unit | Value | Exact factor |
|---|---|---|
| per cent | 0.0000001 % | × 0.0000001 |
| per mille | 0.000001 ‰ | × 0.000001 |
| parts per million | 0.001 ppm | × 0.001 |
| parts per billion (as entered) | 1 ppb | — |
| parts per trillion | 1,000 ppt | × 1,000 |
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 parts per billion to per mille? The converter and the working
- 1.Take the measurement in parts per billion.
- 2.Multiply by 1.0000 × 10^-6 — that is how many per mille fit in one part per billion.
- 3.To go back the other way, divide by 1.0000 × 10^-6, or multiply by 1000000.
Worked example: 25 parts per billion to per mille
- Formula
- ppb × 1.0000 × 10^-6 = ‰
- Arithmetic
- 25 × 1.0000 × 10^-6 = 0.000025 ‰
- Answer
- 25 ppb = 0.000025 ‰
The factor is rounded for display; the figure above is computed from the full value.
Parts per billion to per mille conversion table
| Parts per billion | Per mille |
|---|---|
| 1 ppb | 0.000001 ‰ |
| 2 ppb | 0.000002 ‰ |
| 3 ppb | 0.000003 ‰ |
| 4 ppb | 0.000004 ‰ |
| 5 ppb | 0.000005 ‰ |
| 6 ppb | 0.000006 ‰ |
| 7 ppb | 0.000007 ‰ |
| 8 ppb | 0.000008 ‰ |
| 9 ppb | 0.000009 ‰ |
| 10 ppb | 0.00001 ‰ |
| 12 ppb | 0.000012 ‰ |
| 15 ppb | 0.000015 ‰ |
| 20 ppb | 0.00002 ‰ |
| 25 ppb | 0.000025 ‰ |
| 50 ppb | 0.00005 ‰ |
| 100 ppb | 0.0001 ‰ |
| 200 ppb | 0.0002 ‰ |
| 300 ppb | 0.0003 ‰ |
| 500 ppb | 0.0005 ‰ |
| 1000 ppb | 0.001 ‰ |
| 2000 ppb | 0.002 ‰ |
| 5000 ppb | 0.01 ‰ |
| 10000 ppb | 0.01 ‰ |
What is a part per billion?
One in a thousand million, on the short scale. The EPA states lead and arsenic limits in it, and the ambiguity of "billion" is exactly why NIST asks for 10⁻⁹ instead.
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 part per billion?
One part per billion is 1.0000 × 10^-6 per mille. Going the other way, one per mille is 1000000 parts per billion. 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 part per billion.
Source: NIST SP 811 §7.10.3 — why ppm, ppb and ppt should be avoided and what they mean
Cite this page
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- Rule Calculator. (2026). Convert Parts per billion to per mille. Rule Calculator. https://rulecalculators.com/convert/ppb-to-permille
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- Rule Calculator. "Convert Parts per billion to per mille." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/ppb-to-permille.
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Questions people actually ask
- How many per mille are in a part per billion?
- 1.0000 × 10^-6. 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 parts per billion?
- Divide by 1.0000 × 10^-6, or multiply by 1000000 — they are the same operation.
Other concentration conversions
Per mille to parts per billion — the same conversion the other way.