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Sugar Addition Calculator

Calculate pure sugar to add using a starting mixture’s sugar content and a target mass percentage. See total mass and a reconstructed concentration.

Use this result well

Inputs that matter
Starting mixture mass, Existing sugar, Target sugar, Mass unit
Output to expect
Sugar to add
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Conserve sugar and total mass

Let M be starting mass, i the existing sugar fraction and t the target fraction. Solve (Mi + S) / (M + S) = t for added pure sugar S. The calculation excludes evaporation and other ingredient changes.

S = M × (t − i) / (1 − t)

Use a sugar mass fraction

Existing sugar must refer to the whole starting mixture. Refractometer soluble-solids readings can estimate sugar in a suitable product but also respond to other dissolved material.

Source: Penn State Extension: soluble solids in fruit preserves

Keep recipe requirements separate

A mass balance does not determine gel formation or preserving conditions. Retain the tested recipe’s fruit, acid, pectin, sugar and complete process.

Source: NCHFP: Jellied Product Ingredients

Updated: September 2026

Example Scenarios

Start with 1,000 g containing 10% sugar and enter a 50% target.

→ Add 800 g sugar; the 1,800 g mixture contains 900 g total sugar.

Enter 1 kg, 10% existing sugar and 50% target, with kilograms selected.

→ Add 0.8 kg sugar; final mixture mass is 1.8 kg.

Enter an existing percentage of 20% and target of 10%.

→ The target is rejected; no amount is supplied.

Common Mistakes to Avoid

Treating fruit as sugar-free

Supply its applicable starting sugar mass fraction; include all material already in the mixture.

Using the result as a finished jam or storage specification

Boiling can change mass, and gel formation and preservation depend on the complete recipe and process.

FAQ

Starting mass already contains sugar. The balance is (starting sugar + added sugar) / (starting mass + added sugar) = target fraction.

Adding pure sugar cannot reduce the fraction. A target of 100% cannot remove the non-sugar material already present.

Brix is based on a sucrose solution scale. Other dissolved material in fruit products contributes to the reading, so it is not automatically a measured sugar mass percentage.

Use the complete tested recipe unchanged. This calculation describes a mixture and does not validate canning, gel formation or storage.

The required addition is zero and the mixture mass remains unchanged.

About Sugar Addition Calculator

Calculate the pure sugar needed to bring a specified starting mixture to a target sugar mass fraction. Existing sugar, added sugar and final mixture mass are shown separately.