Saltwater Mixing Calculator: Scale Your Salt Mix Recipe

Before you use this: this tool scales your salt mix's own recipe to a different volume — it doesn't change the target salinity that recipe produces, and it can't confirm your product has dissolved fully or reached the intended reading. Always verify the actual mixed batch with a refractometer or hydrometer before adding it to your tank.

Enter exactly what your salt mix's label states, and how much saltwater you want to prepare. Nothing here is pre-filled or assumed for you.

Your salt mix's stated recipe

Usually worded like "use this much salt mix per this much purified water."

Salt mix amount

Unit

Per this much water

Unit

How much saltwater you want to prepare

Target batch volume

Unit

Your results

What this calculator is — and isn't

This is a narrow arithmetic tool with one job: turning "my label says X amount per Y litres or gallons" into the equivalent amount for the batch volume you actually want to mix, correctly and consistently. It doesn't hold a database of salt mix brands or formulations, doesn't predict your resulting specific gravity, and doesn't let you target a different salinity than your product's own recipe is designed to produce — that would require assuming a linear salt-to-salinity relationship this calculator can't verify from a label alone.

If you're not yet sure what target salinity to aim for, our salinity and specific gravity guide covers testing methods and commonly used target ranges.

Common saltwater-mixing mistakes

Adding water to the tank before it's fully mixed and dissolved. Let the batch circulate with a powerhead or pump until completely clear and dissolved before using it.
Never checking the actual result with a refractometer or hydrometer, trusting the calculation alone without confirming the real reading.
Using tap water instead of purified (RO/DI) water for the mixing batch, introducing contaminants a marine system is often more sensitive to than a freshwater one.
Applying a different product's recipe to yours. Salt mix formulations genuinely vary between brands — always use your own product's own label.
Mixing at a different water temperature than the label assumes, which can affect how readily the salt dissolves and how the final reading settles.

How AquaPulse helps

Getting today's batch right is one calculation. Knowing whether the salt mix you're using has been consistent from bag to bag — whether this batch's actual tested reading matches the last one at the same recipe — is a different problem, and it's the one a single calculation can't answer on its own.

AquaPulse works from what you enter — it doesn't test your mixed water automatically. Logging your specific gravity readings in AquaPulse after each batch keeps a record you can compare, so you can catch a genuine formulation or measuring inconsistency rather than assuming every batch behaves identically. Get AquaPulse on the App Store or Google Play to try it.

Keep going

Common questions

Frequently asked questions

Does this calculator tell me what specific gravity my mix will reach?

No. This tool scales your salt mix product's own stated recipe to your target batch volume — it doesn't know or predict the resulting specific gravity, since that depends on your specific product's formulation. It assumes you're following the same recipe ratio your product's label already states for its intended salinity, just scaled to a different volume. Always verify the actual result with your own refractometer or hydrometer before using the batch.

Can I use this to target a different salinity than my product's stated recipe?

No, deliberately. Changing the salt-to-water ratio to hit a different target salinity than your product's own recipe would require assuming a linear relationship between salt mass and specific gravity that varies by formulation and isn't something this calculator can verify from a label alone. It only scales the same recipe to a different total volume — for a different target, follow your product's own instructions for that target if provided, or check with the manufacturer.

Why isn't there a dropdown to pick my salt mix brand?

Deliberately. This calculator doesn't hold a database of salt mix brands or formulations, and never will — recipes genuinely vary between products, and presenting a fixed figure for a named brand would risk being wrong or outdated. Instead, you enter the amount and reference volume printed on your own product's label, and the calculator scales that to your target batch.

Do I need to test the water after mixing?

Yes, always. This calculator only checks your arithmetic — it doesn't confirm the salt has fully dissolved, that your scale or measuring method matches what the label assumes, or that the batch has actually reached your intended salinity. Test with a refractometer or hydrometer before adding the water to your tank, particularly for a display already stocked with livestock.

How this calculator works: the result is your salt mix amount, multiplied by (your target volume ÷ your recipe's reference volume) — pure ratio scaling of your own product's recipe, with no salt-mix-brand data built in. Volume unit conversions use exact published constants (1 US gallon = 3.785411784 litres, 1 UK gallon = 4.54609 litres). Nothing you enter is saved or sent anywhere.

What we deliberately left out: any list or database of salt mix brands or formulations; any target-salinity adjustment beyond your product's own stated recipe, for the reasons explained above; and any assumption about your water's starting salinity before mixing — this calculator assumes you're mixing from purified (RO/DI) water, consistent with standard practice, not correcting an existing saltwater batch.

Sources and editorial information

Published: 8 August 2026
Last reviewed: 8 August 2026
Written and maintained by: AquaPulse (Valeon Labs Ltd)

This calculator and its supporting content are written and maintained by the AquaPulse team at Valeon Labs Ltd. The arithmetic uses only the figures you enter from your own product's label and your own target volume — there is no built-in salt-mix brand or formulation data of any kind. We'll update this page if we find something we've got wrong.

Good to know: This tool provides arithmetic assistance only. It does not predict your resulting salinity, does not test your water for you, and does not replace verifying the actual mixed batch with a reliable refractometer or hydrometer.

Saltwater Mixing Calculator