Altitude & Processing Time

Chapter 01

Why elevation changes the schedule

As elevation increases, atmospheric pressure decreases and water boils at a lower temperature. For boiling-water canning, tested schedules compensate by adding processing time above the stated elevation threshold.

Pressure-canning schedules commonly compensate with increased pressure instead of extra time. Always use the table for the canning method actually named in the recipe.

Chapter 02

Read the whole processing table

Choose the row that matches pack style and jar size, then the column that contains your elevation. Do not select a time from another jar size simply because it is shorter or more convenient.

The base time displayed on Canning Vault recipe cards represents the lowest-elevation schedule. Use the elevation tool and confirm the result against the trusted source before processing.

• Confirm your elevation before canning day.
• Match method, pack style, jar size, and elevation.
• Set the timer only after the required boil or pressure is established.

Chapter 03

Protect the processing clock

Keep the canner operating at the required condition for the entire process. In a boiling-water canner, jars must remain covered and the water must stay at a boil.

If the boil stops during a boiling-water process, restore a full boil and restart the processing time from the beginning. Do not add only the minutes that were lost.

Chapter 04

Why a nearby time is not close enough

Tested times account for acidity, thickness, food-piece size, solid-to-liquid ratio, starting temperature, jar shape, jar size, and pack style. A schedule from a similar-looking product cannot safely be transferred to a new formula.

If a current authoritative source does not provide a process for the product and jar size you want, refrigerate, freeze, or choose a different tested recipe.