Altitude Canning Adjustment Calculator

Boiling-water canning is already capped at water's boiling point, so the only way to deliver more heat energy at a lower boiling point is to leave the jars in longer. Pressure canning works differently: a sealed canner raises the internal temperature above 212°F by increasing pressure, and at altitude the same PSI setting produces a lower internal temperature than it would at sea level. Raising Required PSI restores that higher processing temperature, so the published processing time for the food itself stays valid — only the pressure setting changes.

A weighted-gauge canner controls pressure with physical metal weights you hang on the vent pipe, and most only come in 5 or 10 and 15-pound weights — there is no way to set it to, say, 12 PSI. That forces it to jump straight from 10 PSI (at or below 1,000 ft) to 15 PSI (anywhere above 1,000 ft) with nothing in between. A dial-gauge canner has a needle you read against a printed scale, so it can be set to any whole PSI value, which is why its published table climbs gradually — 11 PSI up to 2,000 ft, then one more pound of pressure for every additional 2,000 ft of elevation.

It depends on which direction you're wrong. Using the dial-gauge figure on a weighted-gauge canner isn't possible past 1,000 ft since weighted-gauge canners only offer 10 or 15 PSI weights — but using a WATER-BATH time or an under-pressurized PSI setting on a low-acid food is a genuine Clostridium botulinum risk, because the jar's contents never reach the temperature needed to destroy the bacteria's heat-resistant spores. Always confirm which gauge type your canner has (it's stamped on the lid or in the manual) before relying on a calculated PSI.

No — altitude adjustments in NCHFP-published recipes are not a safety margin you can skip, they are the difference between a jar that reaches a safe internal temperature and one that doesn't. At 5,000 ft, water boils at roughly 203°F instead of 212°F, so a boiling-water recipe run at the sea-level time alone would spend the entire process below the temperature the recipe was validated at. Always add the full Time Added (or set the full Required PSI) for your actual elevation, not a partial adjustment.

No — Base Processing Time has to come from a tested recipe for that specific food, jar size, and preparation method (NCHFP, USDA, or a Cooperative Extension publication). This calculator only takes that already-published sea-level number and applies the correct altitude adjustment for your Canning Method and, for pressure canning, your canner's Gauge Type. It cannot tell you whether a food needs water-bath or pressure canning in the first place, or how long the untested sea-level time should be.