Salinity PPM Calculator
Oceanographers say "35 ppt", aquarists say "35,000 PPM" — same water. Multiply ppt by 1,000 to move between the two.
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Salinity PPM Calculator
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Oceanographers say "35 ppt", aquarists say "35,000 PPM" — same water. Multiply ppt by 1,000 to move between the two.
How to use this calculator
- Enter salinity in ppt.
- Multiply by 1,000.
- Read PPM.
The formula
ppt here means parts per thousand; ×1,000 gives parts per million.
What the units mean
ppt (salinity) — parts per thousand as oceanographers use it. Seawater is about 35 ppt; brackish water sits between fresh and seawater.
PPM (parts per million) — one part of solute per million parts of the total mixture. The workhorse unit for trace concentrations in water, air, and food.
Worked example
Brackish water at 5 ppt → 5,000 PPM.
Quick reference
| Water type | ppt | PPM |
|---|---|---|
| Fresh | <0.5 | <500 |
| Brackish | 0.5–30 | 500–30,000 |
| Seawater | 35 | 35,000 |
| Brine | >50 | >50,000 |
ppt = parts per thousand here.
Where you will actually use this
Marine tank targets, desalination specs, and brackish-water classifications all use different units.
- Marine aquariums
- Desalination
- Estuary studies
Mistakes that give wrong answers
- Confusing ppt (thousand) with ppt (trillion) — context matters
Key takeaways
- Formula: PPM = salinity (ppt) × 1,000
- Remember: ppt = parts per thousand here.
- Watch out for: Confusing ppt (thousand) with ppt (trillion) — context matters
- Next step: run your own numbers in the calculator above, then verify with a measurement — calculated values are only as good as the inputs.
Frequently asked questions
What is seawater salinity in PPM?
About 35,000 PPM.
What is brackish water in PPM?
Roughly 1,000–10,000 PPM.