Specific gravity to practical salinity units
Type a value in SG to get it in PSU instantly.
40PSU
That's about the same as the Red Sea. Every liter holds about 40 g of dissolved salt.
Convert the other way: PSU to SG
What it means
How salty is that?
Specific gravity depends on temperature. Aquarium hydrometers are usually calibrated at 25 °C, and a reading taken cold will be wrong.
The math
How to convert SG to PSU
Specific gravity rises with salt: SG ≈ 1 + PSU × 0.00075 at 25 °C, and conductivity runs at roughly 0.656 mS/cm per PSU for ordinary seawater.
Example: 1.03 SG = 40 PSU.
Every unit
Your salinity in every unit
Tables
SG to PSU conversion table
| SG | PSU |
|---|---|
| 1.01 SG | 13.3333 PSU |
| 1.02 SG | 26.6667 PSU |
| 1.03 SG | 40 PSU |
| 1.04 SG | 53.3333 PSU |
PSU to SG conversion table
| PSU | SG |
|---|---|
| 0.5 PSU | 1.00038 SG |
| 1 PSU | 1.00075 SG |
| 5 PSU | 1.00375 SG |
| 10 PSU | 1.0075 SG |
| 15 PSU | 1.01125 SG |
| 20 PSU | 1.015 SG |
| 25 PSU | 1.01875 SG |
| 30 PSU | 1.0225 SG |
| 35 PSU | 1.02625 SG |
| 40 PSU | 1.03 SG |
| 50 PSU | 1.0375 SG |
Quick answers
Quick answers
- How many PSU is 1 SG?
- 1 SG is 0 PSU.
- How many PSU is 10 SG?
- 10 SG is 12,000 PSU.
- How many PSU is 1.03 SG?
- 1.03 SG is 40 PSU.
The units
About these units
Specific gravity (SG)
What an aquarium hydrometer reads, at 25 °C.
Practical salinity units (PSU)
The oceanographic standard, measured by conductivity.
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