Bottling Yield Calculator

Divide your total batch volume by the usable volume of each container (container size minus headspace). Round up to the nearest whole number. Always prepare 1-2 extra containers in case your yield is slightly more than expected.

Headspace is the gap between the top of the contents and the lid. UK and NCHFP guidance is about 6mm (a quarter inch) for jam, marmalade, curd and chutney, and about 12mm (half an inch) for whole fruit in syrup, which needs more room because the fruit and syrup expand during heat processing. Thin liquids such as cordials and sauces can be filled a little higher, around 5mm. Headspace lets a strong vacuum seal form as the jars cool.

Yes, always sterilise 1-2 more containers than you think you need. Batch yields can vary depending on cooking time, evaporation, and how full you fill each jar. Having spare sterilised containers means you do not waste any of your batch.

Wash in hot soapy water, then sterilise in one of these ways: oven at 140C for 15 minutes; boiling water for 10 minutes; or run through a dishwasher hot cycle. Sterilise lids separately by pouring boiling water over them (do not oven-sterilise rubber seals). Fill jars while still hot.

Not directly — the calculation is based on volume. However, thicker preserves like chutney can be harder to pour cleanly, so you may lose a small amount to what clings to the pan. Accounting for 5-10% extra is sensible for thick preserves.