Canning altitude adjustment

Water boils cooler as you go up. This is the correction — and the line between water bath and pressure canner.

Result

Your elevation1000 ft

Canner typePressure canner — dial gauge

Water boils here at

210.2°F

Which is why altitude changes everything below.

Dial gauge pressure

11 psi

0–2,000 ft: 11 · 2,001–4,000: 12 · 4,001–6,000: 13 · 6,001–8,000: 14 psi.

Have the gauge tested

Annually

Extension offices test dial gauges, often free. A gauge reading 2 psi high is an under-processed load.

Boiling water kills botulinum spores?

No. 212°F never does.

240°F under pressure does. That is the entire reason pressure canners exist.

What this will not do

The pH 4.6 line is the whole of canning safety. Above it — vegetables, meat, beans, most tomatoes without added acid — it is a pressure canner or nothing. No amount of boiling substitutes.
Use tested recipes. USDA's Complete Guide to Home Canning, the NCHFP, and your extension service publish processes that were actually validated in a lab. A confident family recipe is not a validated process, and neither is anything a model tells you.
This calculator gives the standard published altitude adjustments only. It does not give you processing times — those come from the tested recipe for your specific food, jar size and pack style.
If a jar failed to seal, refrigerate and eat it, or reprocess within 24 hours. Never store a jar that didn't seal.

The full build and the reasoning are in Chapter 37 of the guide.