Work out jam sugar ratio instantly with clear inputs, formula shown and shareable results.
Sugar is set per kilogram of prepared fruit, and yield is roughly 75% of the combined weight after boiling off water; finished jam needs about 65 Brix to set and keep. Sugar is the preservative as well as the sweetener, so cutting the ratio below about 0.6 kg per kg of fruit gives a jam that must be refrigerated and eaten quickly.
Sugar quantity
sugar kg = fruit kg x sugar per kg of fruit
Yield
yield kg = (fruit + sugar) x 0.75 after evaporation
sugar kg = fruit kg x sugar per kg of fruit. Sugar is set per kilogram of prepared fruit, and yield is roughly 75% of the combined weight after boiling off water; finished jam needs about 65 Brix to set and keep.
Sugar is the preservative as well as the sweetener, so cutting the ratio below about 0.6 kg per kg of fruit gives a jam that must be refrigerated and eaten quickly.
Enter prepared fruit, sugar per kg of fruit, jar size. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.