Jam Pectin Calculator

About this calculator

Pectin is the naturally occurring carbohydrate in fruit cell walls that gels jam and preserves when it's heated with sugar and acid — but different fruits contain wildly different amounts of it. High-pectin fruits like apples, citrus, and currants set easily on their own, while low-pectin fruits like strawberries and peaches typically need added pectin (liquid or powdered) to reach a proper set, and the sugar ratio in the recipe affects both the set and the shelf life.

This calculator works out how much pectin and sugar a batch needs based on the fruit's weight, its natural pectin level, and your target sugar ratio. It's a practical aid for home preservers and jam-makers, helping avoid the classic failure modes of runny jam (too little pectin or sugar) or an overly stiff, rubbery set (too much).