Salinity Calculator

Salinity — the concentration of dissolved salt in water — is measured in several different units, and converting between them is essential for aquarium keeping, aquaculture, and water testing. The Salinity Calculator lets you convert between salinity units by entering an Input Salinity Value and selecting your Input Unit (ppt, specific gravity, or conductivity) to get results across all three formats. Switch to Calculate salt needed mode and enter your water volume, current salinity, and target salinity to find exactly how much salt is required to hit your goal.

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Temperature affects salinity measurements

Results

Converted Salinity

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Parts Per Thousand (ppt)

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Specific Gravity

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Conductivity

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Salt Required

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Frequently Asked Questions

What is the ideal salinity level for a saltwater pool?

The ideal salinity level for a saltwater pool is typically between 2,700-3,400 ppm (parts per million), which is equivalent to about 2.7-3.4 ppt. This is much lower than ocean water, which is around 35 ppt.

How do I convert specific gravity to parts per thousand (ppt)?

To convert specific gravity to ppt, use the formula: ppt = (Specific Gravity - 1) × 1000. For example, a specific gravity of 1.025 equals 25 ppt salinity.

What is the difference between conductivity and salinity?

Conductivity measures how well water conducts electricity (measured in mS/cm), while salinity measures the total amount of dissolved salts (measured in ppt or ppm). Higher salt content increases conductivity, so they're related but not identical measurements.

How much salt does my pool need to reach the target salinity?

The amount of salt needed depends on your pool volume, current salinity level, and target salinity. Generally, you need about 8-10 pounds of salt per 1,000 gallons to increase salinity by 1,000 ppm.

Does water temperature affect salinity measurements?

Yes, temperature affects salinity measurements because it influences water density and conductivity. Most salinity meters automatically compensate for temperature, but manual calculations should account for temperature variations.

What's the salinity level of ocean water?

Ocean water typically has a salinity of about 35 ppt (35,000 ppm) or a specific gravity of 1.025. This is much higher than what's used in saltwater pools or most aquarium applications.

How often should I test my pool's salinity level?

Test your saltwater pool's salinity at least once a week during swimming season. More frequent testing may be needed after heavy rainfall, adding fresh water, or if you notice changes in water quality.