Salinity Converter
Compare SG, PPT, PSU and conductivity using simplified aquarium salinity conversions.
SG, ppt, PSU and mS/cm are used in both US and metric aquariums. No gallon conversion is needed.
Check the entered values and ranges before calculating.
Result
Reference band used here: 33-35 PPT (approximate conversions)
Read these salinity conversions as approximations
SG, PPT, practical salinity (often labeled PSU) and conductivity describe related measurements, but they are not interchangeable definitions. The tool uses simple linear conversions for quick comparison, without a temperature input.
Formula and units
SG ≈ 1 + (PPT + 0.2) × 0.0007. Conductivity (mS/cm) ≈ PPT × 1.5. This tool treats the numeric PSU value as equal to PPT.
Worked example
Entering 35 PPT gives approximately 1.0246 SG, 35 PSU and 52.50 mS/cm with these formulas. These outputs illustrate the calculator’s model; they are not certified reference values for seawater or instrument calibration.
Assumptions and limits
Practical salinity is dimensionless; absolute salinity is expressed in g/kg. Scientific conductivity conversions also use temperature and pressure. For a measurement decision, follow your instrument’s calibration and temperature guidance rather than treating this approximation as a standard.
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Frequently Asked Questions
Are PPT and PSU the same?
Not strictly. PPT describes parts per thousand, while practical salinity is a dimensionless scale commonly labeled PSU. This simplified tool treats their numeric values as equal; it does not calculate absolute salinity.
Why does my meter show a different SG or conductivity?
Temperature, calibration and the instrument’s salinity model affect the reading. This calculator uses linear approximations without temperature compensation. Use your instrument’s instructions and reference solution for calibration.
Can I calibrate my refractometer with these results?
No. These estimates are for comparison only and are not a calibration standard. Use a suitable reference solution and the calibration procedure specified for your instrument.
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