Clear single-column workflow Switch between %w/w and %w/v Supports seawater and additives

Brine concentration calculator

Calculate the salt needed for a target concentration, switch between %w/w and %w/v, and reverse-check the percentage from the salt you actually used.

Includes starting salinity for seawater or existing brine, optional additives such as sugar, g/oz display, and approximate spoon-volume conversions.

See the salt amount required for a target concentration at a glance.
Switch between %w/w (weight %) and %w/v (weight/volume %) and compare both definitions.
Account for starting salinity when you begin with seawater or existing brine.
Include additives such as sugar in the final weight for %w/w calculations.
Reverse-calculate the current percentage from the salt you actually used.
Reuse a setup with shareable URLs and restore the previous state.

How to Use

  1. Choose %w/w or %w/v and check the short definition and example first.
  2. Enter the target salt percentage and the amount of liquid.
  3. If needed, open the advanced settings for initial salinity, additives, and display units.
  4. Read the salt-to-add result, then use the reverse card to confirm the percentage from your actual measured salt.

Examples

Make a 5% brine in %w/w

Input

5.0% w/w, 1000 g

Output

Salt to add: 52.6 g, predicted concentration: 5.00%

Make a 5% salt solution in %w/v

Input

5.0% w/v, 1000 mL

Output

Salt to add: 50.0 g, predicted concentration: 5.00%

Raise seawater from 3.5% to 5.0% w/w

Input

Target 5.0%, initial 3.5%, 1000 g

Output

Salt to add: 15.8 g

Reverse-calculate after using 50 g

Input

%w/w, 1000 g, actual salt 50 g

Output

Estimated salt %: 4.76%, difference from target: -0.24 pt

Quick glossary

%w/w (weight %)

The percentage of the final mixture's total weight that is salt. A 5% w/w brine contains 5 g of salt per 100 g of mixture.

%w/v (weight/volume %)

The grams of salt per 100 mL of solution. A 5% w/v brine contains 5 g of salt per 100 mL.

Initial salinity

The salt percentage already present in seawater or existing brine before you add more salt.

Additives

Ingredients other than salt, such as sugar. In %w/w mode they count toward the final weight.

Formulas

  • %w/w: ds = (t × (m0 + a) - s0) ÷ (1 - t)
  • %w/v: ds = (t - p0) × V
  • %w/w reverse: percent = (s0 + sUsed) ÷ (m0 + a + sUsed) × 100
  • %w/v reverse: percent = (s0 + sUsed) ÷ V × 100

FAQ

What if I start with seawater or an existing brine?

Enter the current salinity in Advanced settings under “Initial salt %”. The result shows how much additional salt to add. If the starting salinity is already above the target, dilute rather than adding salt.

Can I see the result in oz instead of g?

Yes. Switch the display unit between g and oz in Advanced settings. The calculation itself is normalized to grams internally.

Can I add sugar too?

Yes. Add sugar or other ingredients in Advanced settings. In %w/w they count toward the final weight, so the same salt amount produces a slightly lower percentage. In %w/v they appear only as a note and do not change the main calculation.

When should I choose %w/w or %w/v?

Choose %w/w when you weigh the batch and want repeatable results. Choose %w/v when the process is controlled by volume. For a nominal 5% brine at 1 L, %w/w needs about 52.6 g while %w/v needs 50 g.

Are spoon conversions exact?

No. Spoon estimates vary a lot with grain size and salt type. Choose them only as rough guidance and weigh in grams for accurate work. The same check can be repeated as the workflow changes.

Does this page also cover food safety or recipe guidance?

No. The page only calculates concentration. Maintain sanitation, storage time, temperature control, safety, and complete recipe decisions in separate documentation. The same check can be repeated as the workflow changes.

Important notes

  • This page calculates concentration only. Manage food safety, sanitation, storage time, temperature control, and recipe decisions separately.
  • Spoon-volume conversions are estimates only. Weigh in grams when accuracy matters.
  • %w/v is a practical volume-based estimate here; it does not model the exact volume change after salt dissolves.
  • If the starting salinity is above the target, this tool does not calculate the dilution amount.