Saltwater Aquarium Salt Mix Calculator
Estimate salt mix for preparing new saltwater, using US gallons or liters.
US liquid gallons (1 US gal = 3.785411784 L). Switching units converts your entries.
Check the entered values and ranges before calculating.
Result
Follow your salt manufacturer’s mixing time and instructions.
Prepare new saltwater in a separate container; check salinity and temperature before use.
Estimate salt for a new batch of water
Enter the amount of new water you are preparing, not the entire aquarium unless you are filling it. Choose a preset or Other brand / label instructions to enter the salt mass, corresponding water volume and resulting salinity from your package. The calculator scales that recipe to your target.
Formula and units
Salt (g) = new water volume (L) ÷ label water volume (L) × label salt mass (g) × target PPT ÷ label PPT. Presets use a 1 L reference at 35 PPT. One US gallon is about 3.78541 L.
Worked example
At a reference of 35 g/L and a target of 35 PPT, a 10 US gallon batch needs about 1,325 g of mix: 46.73 oz or 2.92 lb. This is a starting estimate; the final measured salinity determines any adjustment.
Assumptions and limits
Commercial salt mix is not the same as pure sodium chloride, and formulations differ. Follow the package’s water quality, mixing and storage directions. This calculation is for new saltwater; it does not model raising salinity in an occupied tank.
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Frequently Asked Questions
Can I use a salt brand that is not listed?
Yes. Select Other brand / label instructions and enter the salt mass, corresponding water volume and resulting salinity in PPT from the package. Use grams and liters or ounces and US gallons. The calculator scales that recipe to your batch and target salinity. Measure salinity after mixing; this is an estimate, not a measured result.
Can I use this to raise salinity in an occupied aquarium?
This tool estimates salt for a fresh batch of water, not a correction to existing saltwater. Prepare the mix separately and follow an appropriate gradual adjustment plan. Do not interpret the result as dry salt to add directly to livestock.
Does every salt mix need 24 hours of mixing?
No. Mixing time, temperature and storage guidance depend on the formula. Follow your manufacturer’s instructions, let the mix dissolve fully and measure the salinity before using it.
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