Canning Altitude Adjustment Calculator

Find the USDA/NCHFP altitude adjustment for your elevation — the extra boiling-water processing time, or the dial- and weighted-gauge pressure for pressure canning. Reproduces the tested tables; apply them to your tested recipe.

Inputs
ft
Published table lookup — updates as you type
ResultsLIVE
Add to process time — recipe ≤ 20 min
+5 min
+10 min if the recipe is timed over 20 min
Elevation2,500 ft (762 m)
Recipe timed > 20 min+10 min
Altitude band1,001–3,000 ft
MethodBoiling-water bath
Apply this to a tested recipe. The base time and pressure come from your recipe — never reduce a time or pressure below the tested value.
Formula
USDA Complete Guide Table 1 · boiling water · 1,001–3,000 ft → +5 min (≤20) / +10 min (>20)
How it works

Water boils cooler as you climb: about `212°F` at sea level but only around `198°F` at `7,000` feet. Canning processes are timed and pressured for the heat that actually kills spoilage organisms and, in low-acid foods, botulinum spores — so at altitude you must add time or add pressure to make up the difference. This tool reproduces the tested adjustment tables published by the USDA Complete Guide to Home Canning and the National Center for Home Food Preservation (NCHFP). It looks the numbers up by altitude band; it does not calculate or interpolate them.

Which adjustment applies depends on the method. In a boiling-water bath (for high-acid foods like most fruits, jams, and salsas) the pressure can't change, so you add processing time: `5` to `20` minutes for a recipe timed at `20` minutes or less, and `10` to `40` minutes for a longer one, stepping up by altitude band. In a pressure canner (required for low-acid foods — vegetables, meats, most soups) the time stays the same and the pressure rises. A dial gauge adjusts in fine steps — `11`, `12`, `13`, then `14` pounds as you climb through the bands to `8,000` feet. A weighted gauge can't fine-tune, so it jumps from `10` pounds at or below `1,000` feet to `15` pounds above it.

Start from a tested recipe and apply the adjustment to it — the base time and base pressure come from your recipe, not from this page. Never reduce a time or a pressure. If your elevation is above the highest tested band, the tool will not guess a number; check with NCHFP or your local Extension office. Food safety depends on following a tested process exactly.

Worked example
Elevation `2,500` ft
Boiling-water bath: add `5` min (recipe timed ≤ `20` min) or `10` min (recipe > `20` min)
Pressure canner, dial gauge: process at `12` lb
Pressure canner, weighted gauge: process at `15` lb
(Apply to the base time and pressure from your tested recipe — USDA/NCHFP.)
Questions about canning at altitude
Because water boils cooler as elevation rises, the same processing time delivers less lethal heat. Tested recipes compensate by adding time in a boiling-water bath or pounds of pressure in a pressure canner. Skipping the adjustment can leave food underprocessed and unsafe.
SOURCES — USDA Complete Guide to Home Canning (AIB 539, rev. 2015) · NCHFP · Penn State & SDSU Extension — reproduced verbatim
Altitude adjustments reproduce USDA/NCHFP tested processes — follow a tested recipe exactly; do not reduce times or pressures. Food safety depends on it.
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