Salt divided by water
In a water-based recipe, the salt mass is divided by water mass. A 3% ratio with 1,000 g water requires 30 g salt. The added salt does not appear in the denominator.
This definition is useful when the instructions specify grams of salt for a measured amount of water. Label the result “percentage of water weight” to avoid ambiguity.
Salt divided by salt plus water
In a solution-based recipe, salt is a fraction of the finished salt-and-water mass. With 1,000 g water and a 3% target, rearranging salt ÷ (water + salt) = 0.03 gives 30.93 g salt.
The solution calculation includes salt and water only. It excludes food, sugar and other ingredients.
Salt divided by food plus water
Some equilibrium-style recipes define salt relative to food plus added water, excluding the added salt. With 500 g food, 1,000 g water and 3%, the amount is 45 g.
This is an ingredient convention, not a prediction of salt uptake or final salinity. If the recipe includes salt in the full system mass, the denominator changes again.
How to compare recipes
Write down the ingredient masses, the numerator and the denominator. Then convert both recipes to the same convention. 30 g salt with 1,000 g water is both 3% of water and approximately 2.91% of the solution.
If the source never identifies its basis, ask the recipe author before using it for a process requiring a precise ratio. Do not choose a definition simply because its result resembles a familiar number.