Canning Headspace & Processing Time Guide
Select your food and jar size to get the correct headspace, processing method (water bath or pressure canning), time, and pressure. Altitude adjustment included. Based on USDA/NCHFP guidelines. Nothing uploaded.
What Are You Canning?
Safe Processing Guide
Data based on USDA/NCHFP guidelines. Always use tested recipes from reliable sources. Under-processing risks botulism poisoning. When in doubt, pressure can. This tool is for reference only.
Learn more: method, headspace, and altitude in home canning
The method is fixed by the food
Every entry in this guide carries a locked method. Fruits, jams, jellies, vinegar pickles, and tomatoes with added acid are water bath entries. Every vegetable in the list, along with beef, pork, lamb, poultry, and fish, is a pressure entry, and the guide will not produce a water bath time for any of them.
The split comes down to acidity. Food in Jars' primer on acid and pH puts the line at one number: "If something has a pH of 4.6 or below, it is deemed high in acid and is safe for boiling water bath canning. If the pH is 4.7 or above, it is considered low in acid." The National Center for Home Food Preservation states the consequence plainly: "Pressure canning is the only recommended method for canning meat, poultry, seafood, and vegetables."
Headspace follows the food, not the jar size
Headspace in this guide runs from a quarter inch to an inch and a quarter, and it does not change when you switch jar size. Jams, jellies, dill pickles, and tomato sauce are 1/4 inch (6mm). Most fruits, whole and crushed tomatoes, salsa, relish, and bread and butter pickles are 1/2 inch (13mm).
Green beans, corn, carrots, potatoes, spinach, beef, and fish all take a full inch (25mm). Two entries break the pattern: chicken is the largest gap in the table at 1 1/4 inches (32mm), and beets sit at 1/2 inch even though they are pressure canned like the other vegetables. Too little headspace lets food push up under the lid during processing and interfere with the seal. Too much leaves more air in the jar than the process can drive out.
What altitude actually moves
For water bath foods the guide adds minutes and leaves everything else alone. Nothing up to 1,000 feet, 5 minutes from 1,001 to 3,000, 10 minutes from 3,001 to 6,000, 15 minutes from 6,001 to 8,000, and 20 minutes from 8,001 to 10,000 feet. Quarts of peaches are 30 minutes at sea level and 40 minutes at 5,000 feet, with the added time shown separately so you can see where it came from.
Pressure canning works the other way round. The minutes stay exactly as listed and the pressure goes up by 5 PSI anywhere above 1,000 feet. Quarts of green beans are 25 minutes either way: 10 PSI near sea level, 15 PSI at 3,000 feet. Quarts of beef stay at 90 minutes and step from 11 PSI to 16 PSI.
Two limits are worth knowing about. That 5 PSI jump is the weighted gauge adjustment, and a dial gauge canner is adjusted in smaller steps, so use the chart that came with yours. The water bath table also stops at 10,000 feet, and entering a higher elevation adds no minutes at all, which is the table running out rather than a real answer.
Where the table ends
Some foods have no quart figure on purpose. Pick quarts for fish, relish, salsa, or strawberry jam and the guide says the jar size is not recommended instead of inventing a number. Jam and jelly carry a single 10 minute time, for the half pint jars those recipes assume.
Larger jars need longer because heat takes more time to reach the middle, and the gap can be wide. Whole kernel corn goes from 55 minutes for pints to 85 for quarts, and spinach from 70 to 90. That is also why scaling a pint time up to a quart yourself is a bad idea: these numbers come from tested processes, not from arithmetic.
FAQ
Can I water bath can green beans?
No. Green beans are a pressure entry at 10 PSI, 20 minutes for pints and 25 for quarts. A water bath never gets hotter than boiling water, and boiling does not destroy botulism spores in a low-acid food however long you run it.
Does altitude change pressure canning times?
Not in this guide. Above 1,000 feet it raises the pressure by 5 PSI and leaves the minutes untouched, while water bath foods get extra minutes instead. The 5 PSI step is the weighted gauge adjustment, so check your own manual if you run a dial gauge.
Why is there no quart time for fish?
The tested process behind that entry covers pints only, at 100 minutes and 11 PSI. Where a jar size has no tested time the guide says so rather than scaling one up, since a longer guess in a bigger jar is not the same thing as a tested process.