A quart jar of solids is not a quart of liquid
Pack a quart jar with spears, or halved fruit, or beans, and then pour water in until it reaches the fill line. What goes in is usually somewhere between a quarter and a half of the jar. The rest of the space is already occupied. Anyone who makes brine or syrup by the jar count without allowing for that ends up with roughly three times too much of it.
Measuring the packed share is a two-minute job you do once for each thing you put up. Pack the jar the way you always pack it, pour water in to the line, then tip that water into a measuring cup. The water is the liquid figure; everything above it in the jar was solids.
| Solids share of the jar | Liquid in a 32 fl oz jar filled to the brim | 14 jars |
|---|---|---|
| 25% | 24.0 fl oz | 2.6 gal |
| 50% | 16.0 fl oz | 1.75 gal |
| 65% | 11.2 fl oz | 1.22 gal |
| 80% | 6.4 fl oz | 0.70 gal |
Those figures are before headspace, which takes a further slice off every jar. Whatever headspace your recipe gives, the calculator turns it into fluid ounces using the inside diameter at the fill line, because an inch of headspace in a wide-mouth half gallon is a very different volume from an inch in a half pint.
The stated size and the actual capacity
This page models the nominal size — a quart jar as 32 fluid ounces, a pint as 16 — because that is the number on the box and the number people plan with. A real jar is not exactly that to the rim, and it varies by manufacturer and by whether it is regular or wide mouth. If you have measured yours, put the figure in and the calculator uses it and says so in the output.
The arithmetic underneath is fixed: one US gallon is 231 cubic inches and 128 fluid ounces, so one fluid ounce is 1.8047 cubic inches, so a cylinder 2.5 inches across and one inch deep is 4.91 cubic inches, which is 2.72 fluid ounces — that is the rate the calculator applies to whatever headspace your recipe gives.
Scaling from a recipe that makes something else
Once you know the batch volume, the multiple against your recipe is a division. A recipe that makes four cups is 32 fluid ounces, so a batch needing 172.5 fluid ounces is 5.39 times it. You can either scale by that factor — the recipe scaler handles ingredient lists including the awkward fractions — or run six whole batches and have some left, which is often less fiddly and no more expensive.
Making extra is not waste. Running short on the last jar of a batch means either an unfilled jar or a rushed second pan, and ten per cent costs almost nothing.
What this page will not tell you
It has no strengths, no concentrations, no ratio of salt or sugar to water, no acidity figure, no headspace of its own, no process time and no keeping time, and it makes no judgement about whether anything is safe to eat. Every one of those belongs to a tested recipe from the USDA, the National Center for Home Food Preservation or your state extension service. This page divides a jar into the part that is solid and the part that is not.
Questions people ask
How much brine do I need for a dozen quart jars?
Far less than a dozen quarts. It depends on how tightly the jars are packed, which is why that is the main input. Packed at 65 per cent solids and filled to the brim, a quart jar takes about 11 fluid ounces, so twelve jars is a little over a gallon rather than three. Measure your own packed share once and the figure stops being a guess.
How do I measure the packed share?
Pack one jar exactly as you normally would, then pour water in until it reaches the fill line and tip that water into a measuring cup. The water you poured is the liquid volume; the rest of the fill was solids. It takes two minutes and it is right for your product and your packing hand.
Where does the headspace figure come from?
From the tested recipe you are following. This page supplies none. It converts the inches your recipe gives into fluid ounces using the inside diameter at the fill line, because the same inch of headspace is a very different volume in a half pint and in a half gallon.
Is a quart jar exactly 32 fluid ounces?
To the brim, not exactly, and it varies by maker and by mouth size. The calculator models the nominal size by default because that is what people plan with, and it says so in the output. If you have measured your own jars, there is a field for the measured capacity and it will use that instead.
What about the strength of the brine or syrup?
It gives none, on purpose. This page is quantity and container arithmetic. Process times, pressures, headspace, altitude adjustments and anything about acidity belong to a tested recipe from the USDA, the National Center for Home Food Preservation or your state extension service, and those are the only places to get them. Where the calculator asks for one of those numbers, it is because you are copying it in from the recipe you are already following.