Convert Per cent to Parts per billion
1 per cent is 10,000,000 ppb. One per cent is exactly 10000000 parts per billion.
One per cent is 10000000 parts per billion. To convert per cent to parts per billion, multiply by 10000000; to go the other way, divide by 10000000 or multiply by 1.0000 × 10^-7. 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 × 10000000
1 * 1000000010,000,000 ppb
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 parts per billion? The converter and the working
- 1.Take the measurement in per cent.
- 2.Multiply by 10000000 — that is how many parts per billion fit in one per cent.
- 3.To go back the other way, divide by 10000000, or multiply by 1.0000 × 10^-7.
Worked example: 25 per cent to parts per billion
- Formula
- % × 10000000 = ppb
- Arithmetic
- 25 × 10000000 = 250,000,000 ppb
- Answer
- 25 % = 250,000,000 ppb
The factor is exact, so this figure is exact too — only the display is rounded.
Per cent to parts per billion conversion table
| Per cent | Parts per billion |
|---|---|
| 1 % | 10,000,000 ppb |
| 2 % | 20,000,000 ppb |
| 3 % | 30,000,000 ppb |
| 4 % | 40,000,000 ppb |
| 5 % | 50,000,000 ppb |
| 6 % | 60,000,000 ppb |
| 7 % | 70,000,000 ppb |
| 8 % | 80,000,000 ppb |
| 9 % | 90,000,000 ppb |
| 10 % | 100,000,000 ppb |
| 12 % | 120,000,000 ppb |
| 15 % | 150,000,000 ppb |
| 20 % | 200,000,000 ppb |
| 25 % | 250,000,000 ppb |
| 50 % | 500,000,000 ppb |
| 100 % | 1,000,000,000 ppb |
| 200 % | 2,000,000,000 ppb |
| 300 % | 3,000,000,000 ppb |
| 500 % | 5,000,000,000 ppb |
| 1000 % | 10,000,000,000 ppb |
| 2000 % | 20,000,000,000 ppb |
| 5000 % | 50,000,000,000 ppb |
| 10000 % | 100,000,000,000 ppb |
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 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.
How many parts per billion are in a per cent?
One per cent is 10000000 parts per billion, exactly. Going the other way, one part per billion is 1.0000 × 10^-7 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 parts per billion. Rule Calculator. https://rulecalculators.com/convert/percent-to-ppb
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- Chicago
- Rule Calculator. "Convert Per cent to parts per billion." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/percent-to-ppb.
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Questions people actually ask
- How many parts per billion are in a per cent?
- 10000000. 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.
- How do I convert parts per billion back to per cent?
- Divide by 10000000, or multiply by 1.0000 × 10^-7 — they are the same operation.
Other concentration conversions
Parts per billion to per cent — the same conversion the other way.