Convert Parts per trillion to Parts per million
1 part per trillion is 0.000001 ppm. One part per trillion is exactly 0.000001 parts per million.
One part per trillion is 1.0000 × 10^-6 parts per million. To convert parts per trillion to parts per million, 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 million million.
Factor checked against the defining standard · How we check
- Parts per trillion × 1.0000 × 10^-6
1 * 0.0000010 ppm
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 parts per million? The converter and the working
- 1.Take the measurement in parts per trillion.
- 2.Multiply by 1.0000 × 10^-6 — that is how many parts per million fit in one part per trillion.
- 3.To go back the other way, divide by 1.0000 × 10^-6, or multiply by 1000000.
Worked example: 25 parts per trillion to parts per million
- Formula
- ppt × 1.0000 × 10^-6 = ppm
- Arithmetic
- 25 × 1.0000 × 10^-6 = 0.000025 ppm
- Answer
- 25 ppt = 0.000025 ppm
The factor is rounded for display; the figure above is computed from the full value.
Parts per trillion to parts per million conversion table
| Parts per trillion | Parts per million |
|---|---|
| 1 ppt | 0.000001 ppm |
| 2 ppt | 0.000002 ppm |
| 3 ppt | 0.000003 ppm |
| 4 ppt | 0.000004 ppm |
| 5 ppt | 0.000005 ppm |
| 6 ppt | 0.000006 ppm |
| 7 ppt | 0.000007 ppm |
| 8 ppt | 0.000008 ppm |
| 9 ppt | 0.000009 ppm |
| 10 ppt | 0.00001 ppm |
| 12 ppt | 0.000012 ppm |
| 15 ppt | 0.000015 ppm |
| 20 ppt | 0.00002 ppm |
| 25 ppt | 0.000025 ppm |
| 50 ppt | 0.00005 ppm |
| 100 ppt | 0.0001 ppm |
| 200 ppt | 0.0002 ppm |
| 300 ppt | 0.0003 ppm |
| 500 ppt | 0.0005 ppm |
| 1000 ppt | 0.001 ppm |
| 2000 ppt | 0.002 ppm |
| 5000 ppt | 0.01 ppm |
| 10000 ppt | 0.01 ppm |
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 part per million?
One in a million. The working unit of drinking-water limits, CO₂ in air and dissolved solids — 1 ppm is 1 mg per liter of water, since a liter weighs a kilogram.
How many parts per million are in a part per trillion?
One part per trillion is 1.0000 × 10^-6 parts per million. Going the other way, one part per million is 1000000 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
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- Rule Calculator. (2026). Convert Parts per trillion to parts per million. Rule Calculator. https://rulecalculators.com/convert/ppt-to-ppm
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- Chicago
- Rule Calculator. "Convert Parts per trillion to parts per million." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/ppt-to-ppm.
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Questions people actually ask
- How many parts per million are in a part per trillion?
- 1.0000 × 10^-6. One in a million. The working unit of drinking-water limits, CO₂ in air and dissolved solids — 1 ppm is 1 mg per liter of water, since a liter weighs a kilogram.
- How do I convert parts per million back to parts per trillion?
- Divide by 1.0000 × 10^-6, or multiply by 1000000 — they are the same operation.
Other concentration conversions
Parts per million to parts per trillion — the same conversion the other way.