Food & Cooking
Canning Processing Time
USDA boiling-water-bath times by recipe, jar size, and altitude — with safety guardrails for low-acid foods.
Canning Processing Time
Inputs
Every altitude band adds time — boiling temp drops with elevation.
Results
Processing time
40 min base + 0 min altitude
40 min
Altitude adjust
Applies once water reaches a full rolling boil.
+ 0 min
Low-acid food
Tomatoes are borderline low-acid — add bottled lemon juice (2 tbsp per quart / 1 tbsp per pint) or citric acid (½ tsp per quart / ¼ tsp per pint) before processing. Non-acidified low-acid foods MUST use a pressure canner.
How to use this
Boiling-water-bath canning only works for high-acid foods (pH ≤ 4.6). Tomatoes need added acid to stay safe. Anything low-acid — beans, meat, most vegetables — needs a pressure canner to hit 240°F and kill botulinum spores.
Times are from the USDA Complete Guide to Home Canning. Follow a tested recipe and never reduce sugar, acid, or processing time.
Formula
total_min = base_min (by recipe + jar) + altitude_add
altitude_add: 1000–3000 ft +5; 3000–6000 +10; 6000–8000 +15; 8000–10000 +20
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Formula
total_min = base_min(recipe, jar) + altitude_add (bands: +5/+10/+15/+20)