Convert Parts per trillion to Per cent
1 part per trillion is 1.00e-10 %. One part per trillion is exactly 1e-10 per cent.
One part per trillion is 1.0000 × 10^-10 per cent. To convert parts per trillion to per cent, multiply by 1.0000 × 10^-10; to go the other way, divide by 1.0000 × 10^-10 or multiply by 10000000000. 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 million million.
Factor checked against the defining standard · How we check
- Parts per trillion × 1.0000 × 10^-10
1 * 1e-100 %
1 part per trillion in every concentration unit
| Unit | Value | Exact factor |
|---|---|---|
| per cent | 0.0000000001 % | × 0.0000000001 |
| per mille | 0.000000001 ‰ | × 0.000000001 |
| parts per million | 0.000001 ppm | × 0.000001 |
| parts per billion | 0.001 ppb | × 0.001 |
| parts per trillion (as entered) | 1 ppt | — |
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 trillion to per cent? The converter and the working
- 1.Take the measurement in parts per trillion.
- 2.Multiply by 1.0000 × 10^-10 — that is how many per cent fit in one part per trillion.
- 3.To go back the other way, divide by 1.0000 × 10^-10, or multiply by 10000000000.
Worked example: 25 parts per trillion to per cent
- Formula
- ppt × 1.0000 × 10^-10 = %
- Arithmetic
- 25 × 1.0000 × 10^-10 = 2.50e-9 %
- Answer
- 25 ppt = 2.50e-9 %
The factor is rounded for display; the figure above is computed from the full value.
Parts per trillion to per cent conversion table
| Parts per trillion | Per cent |
|---|---|
| 1 ppt | 1.00e-10 % |
| 2 ppt | 2.00e-10 % |
| 3 ppt | 3.00e-10 % |
| 4 ppt | 4.00e-10 % |
| 5 ppt | 5.00e-10 % |
| 6 ppt | 6.00e-10 % |
| 7 ppt | 7.00e-10 % |
| 8 ppt | 8.00e-10 % |
| 9 ppt | 9.00e-10 % |
| 10 ppt | 1.00e-9 % |
| 12 ppt | 1.20e-9 % |
| 15 ppt | 1.50e-9 % |
| 20 ppt | 2.00e-9 % |
| 25 ppt | 2.50e-9 % |
| 50 ppt | 5.00e-9 % |
| 100 ppt | 1.00e-8 % |
| 200 ppt | 2.00e-8 % |
| 300 ppt | 3.00e-8 % |
| 500 ppt | 5.00e-8 % |
| 1000 ppt | 1.00e-7 % |
| 2000 ppt | 2.00e-7 % |
| 5000 ppt | 5.00e-7 % |
| 10000 ppt | 0.000001 % |
What is a part per trillion?
One in a million million. PFAS limits are set here — the EPA’s 2024 drinking-water rule is 4 ppt, which is four drops in a thousand Olympic pools.
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 part per trillion?
One part per trillion is 1.0000 × 10^-10 per cent. Going the other way, one per cent is 10000000000 parts per trillion. 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 trillion.
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 Parts per trillion to per cent. Rule Calculator. https://rulecalculators.com/convert/ppt-to-percent
- MLA
- "Convert Parts per trillion to per cent." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/ppt-to-percent.
- Chicago
- Rule Calculator. "Convert Parts per trillion to per cent." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/ppt-to-percent.
The date is when the figures on this page were last checked against their source, not the day you opened it. Add your own access date if your style needs one.
Questions people actually ask
- How many per cent are in a part per trillion?
- 1.0000 × 10^-10. 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 parts per trillion?
- Divide by 1.0000 × 10^-10, or multiply by 10000000000 — they are the same operation.
Other concentration conversions
Per cent to parts per trillion — the same conversion the other way.