Jam and jelly in half-pint or pint jars are processed for 5 minutes in a boiling-water canner at 0 to 1,000 ft, 10 minutes at 1,001 to 6,000 ft and 15 minutes above 6,000 ft, in jars sterilised first. Those are the USDA times published by the National Center for Home Food Preservation (NCHFP). Marmalade is the same; apple butter in quarts, reduced-sugar spreads and chutneys take longer. Pick your product, jar and altitude for the exact time.
Boiling-water canner · tested times
Jam or jelly made with added pectin
5 minutes
Half-pint (8 oz, 237 ml) jars at sea level: 0–1,000 ft.
0–1,000 ft
5 min ← you
1,001–6,000 ft
10 min
above 6,000 ft
15 min
Headspace
¼ inch (6 mm)
Jars
Sterilise them: the recipe’s time is under 10 minutes at sea level. Boil the empty jars 10 minutes at your altitude.
Start timing
When the water returns to a full boilKeep it boiling, lid on, with at least 1 inch (2.5 cm) of water over the jars.
Afterwards
Cool 12 to 24 hours, then check every sealReprocess an unsealed jar within 24 hours, or refrigerate it.
Minutes in a boiling-water canner, hot pack, from each product’s table on nchfp.uga.edu. Each time belongs to its tested recipe and jar size: a recipe from elsewhere needs the time its own tested source gives.
Minutes in a boiling-water canner, hot pack. Where a recipe has three altitude bands, one time covers 1,001 to 6,000 ft.
Why altitude adds time
Water boils at a lower temperature the higher you live, and NCHFP explains that lower boiling temperatures are less effective at killing the microorganisms that spoil canned food. The extra minutes make up for it. Jams use three altitude bands; some products, such as the reduced-sugar peach-pineapple spread, use four. The calculator reads the band from your altitude: 1,000 ft exactly is still in the first band, and 1,001 ft is in the second. If you don’t know your altitude, NCHFP suggests asking your county Extension office.
Water bath canning, step by step
Water bath canning, step by step (jellyglimmer.me)
Check the jars and lids. Use Mason-type jars without nicks, new flat lids and screw bands in good condition. Prepare the lids as their maker says. Wash the jars in hot soapy water or a dishwasher; NCHFP notes that washing does not sterilise them.
Sterilise if the time is under 10 minutes. Stand the empty jars upright on the canner rack, cover with hot water by 1 inch and boil 10 minutes, plus 1 minute for every 1,000 ft above sea level. Keep them hot.
Heat the canner. Rack in the bottom, half-full of water, heated to 180 °F (82 °C) for hot-packed food.
Fill hot jars with hot jam, leaving ¼ inch (6 mm) headspace; ½ inch (13 mm) for chutneys. Jams and jellies don’t need air bubbles removed; chutneys do.
Wipe the rims with a clean, damp paper towel, put the lids on and screw the bands on as the lid maker directs.
Load the canner with a jar lifter, keeping the jars upright. Add hot water until it is at least 1 inch (2.5 cm) over the tops; 2 inches for times over 30 minutes.
Time from the boil. Lid on, heat high until the water boils vigorously, then start the timer. Keep a full boil throughout. If it stops boiling, bring it back and start the time again from the beginning.
Lift the jars out when the time is up: heat off, lid off, and after 5 minutes lift each jar straight up onto a towel or rack, 1 inch apart, out of draughts. Don’t tighten the bands.
Cool 12 to 24 hours without moving them, then take off the bands and test every seal: the lid shouldn’t spring back when pressed, should ring when tapped with a spoon, and should curve down slightly.
Deal with any failures within 24 hours: reprocess with a new lid for the same time, or keep the jar in the fridge and eat it within several days.
Label and store the sealed jars in a cool, dark, dry place, 50 to 70 °F (10 to 21 °C), and use them within a year.
Jars upright on the rack, at least 1 inch of boiling water over them; ¼ inch of headspace under each lid.
What can’t be water-bath canned
Low-acid foods need a pressure canner. USDA guidance: foods with a pH above 4.6 are low-acid, including red meats, seafood, poultry, milk and all fresh vegetables except most tomatoes. Mixtures of low-acid and acid foods are low-acid too unless the recipe adds enough lemon juice, citric acid or vinegar. Botulinum spores are very hard to destroy at boiling-water temperatures, so these foods are processed at 240 to 250 °F (116 to 121 °C) in a pressure canner.
Fruits, jams, jellies, marmalades, fruit butters and pickles are acid foods (pH 4.6 or lower) and are safe in boiling water by a tested recipe. Tomatoes and figs sit close to the line, which is why their tested recipes add lemon juice or citric acid. A chutney mixes acid fruit with low-acid onions or peppers, and its tested recipe sets enough vinegar to keep the whole jar acid, so keep to the amounts. NCHFP’s apple chutney, for example, lets you change the type of hot pepper only if you don’t exceed the listed measurement.
Methods the USDA doesn’t recommend
Open-kettle canning, filling hot jars and sealing them with no processing, and processing filled jars in an oven, microwave or dishwasher. NCHFP: these “do not prevent all risks of spoilage”.
Paraffin or wax seals on any sweet spread, because of mould.
Turning jars upside down instead of processing. USDA and NCHFP give no inversion method; every tested jam recipe uses the canner.
Retightening bands on hot jars, which can cut through the sealing compound.
Worked examples
Strawberry jam with pectin, half-pints, 3,500 ft (1,067 m): 10 minutes, in sterilised jars.
Apple butter in quarts, 500 ft: 10 minutes. The recipe says quart jars needn’t be sterilised first.
Peach-pineapple spread in pints, 4,000 ft: 30 minutes, the third of its four bands.
Cranberry-orange chutney for Thanksgiving on Thursday 26 November 2026, half-pints at sea level: 10 minutes, ½ inch headspace.
5 minutes for half-pints or pints at 0 to 1,000 ft, 10 minutes at 1,001 to 6,000 ft and 15 minutes above 6,000 ft, in jars sterilised first. Time it from when the water returns to a full boil.
How do I adjust canning time for altitude?
Use the altitude column of the product’s own table. For jams and jellies that adds 5 minutes above 1,000 ft and 10 minutes above 6,000 ft. Some products, like the reduced-sugar peach-pineapple spread, have four altitude bands.
Do I need to sterilize jars for water bath canning?
Only when the processing time is under 10 minutes, as it is for most jams and jellies at sea level. NCHFP says jars for foods processed 10 minutes or longer need not be sterilised first, just clean and hot.
What if the water stops boiling during processing?
Turn the heat to high, bring the water back to a vigorous boil and start timing again from the beginning, using the full original time. The University of Georgia notes this may affect quality, but it matters for safety.
Can I water bath can vegetables or meat?
No. They are low-acid foods (pH above 4.6) and need a pressure canner, which reaches 240 to 250 °F. Only acid foods such as fruit, jam, pickles and acidified tomatoes go in a boiling-water canner.
Sources
Every processing time: the table on each product’s page at nchfp.uga.edu, linked from the result card (USDA Complete Guide to Home Canning, revised 2015, or University of Georgia tested recipes; checked 5 November 2026).