How to Test a Canning Dial Gauge
Have a dial gauge tested for accuracy every year, before canning season, through your local cooperative extension office or the manufacturer. An inaccurate gauge can under-process low-acid food, a botulism risk, so testing is a safety step, not optional.
On a dial-gauge pressure canner, that needle is a safety instrument. If it reads high, your food is under-processed, and for low-acid foods that means a botulism risk. Testing it is a small yearly job that protects everyone who eats what you can.
Test it every year
Dial gauges can drift over time, so the standard advice is to have yours tested once a year, before you start canning. This is not a task you do at home by eye; it needs proper test equipment.
Where to get it tested
- Local cooperative extension office. Many test dial gauges, often free or for a small fee. Search for your county extension's food preservation service.
- The canner manufacturer. They can test, recalibrate or replace a gauge; contact them for the process.
If a gauge reads more than a small amount off, it should be replaced. Never rely on a gauge you suspect is inaccurate.
The weighted-gauge alternative
Weighted-gauge canners regulate pressure mechanically, by venting steam, so they do not go out of calibration and never need this annual test. Many canners prefer them for exactly this reason. They still need the vent pipe and safety parts kept clean and clear. Some canners have both a dial and a weight.
Choosing or maintaining a canner? See the best pressure canners.
- National Center for Home Food Preservation (NCHFP) — tested home-preservation methods and the USDA Complete Guide to Home Canning
- USDA Food Safety and Inspection Service (FSIS)
- U.S. Food & Drug Administration (FDA) — Food
- FoodSafety.gov
Frequently asked questions
How often should a canning dial gauge be tested?
Once a year, before the canning season, is the standard recommendation. Gauges can drift out of accuracy over time.
Where can I get my canning gauge tested?
Many local cooperative extension offices test dial gauges, often free or low-cost. The canner manufacturer can also test or replace gauges.
Do weighted-gauge canners need testing?
No. Weighted gauges regulate pressure mechanically and do not go out of calibration, which is why many people prefer them; they still need the parts kept clean and clear.