Canning Safety Planner
Check whether a method is unsuitable for low-acid foods and count batches; use a tested recipe for processing time and pressure.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
This planner only checks a basic method warning and batch count. It does not calculate processing time or pressure. A safe process depends on the exact food, preparation, jar size, canner, pack style and altitude; follow a tested recipe for those details.
Worked example
calculated with the default values below
Canning method Water bath (high acid) · What you are canning Tomatoes (acidified) · Number of jars 6 · Jars per batch 6 Batches needed 1 · Method status Method requires a tested recipe · Processing guidance Use a tested recipe for the exact food, pack style, jar size, canner gauge and altitude; do not infer time or pressure from these inputs.
General background references
Disclaimer
These calculators give general cooking guidance. Ingredient density, oven calibration, altitude and equipment all vary, and safe minimum internal temperatures always take precedence over timings. Follow the food-safety advice issued by your national authority.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
n_b = ⌈j ÷ b⌉
- j
- Total jars
- b
- Jars per batch
- n_b
- Batches
Only batch count is calculated. A tested recipe must supply time and pressure for the exact food, pack style, jar, canner and altitude. Low-acid foods must not be water-bath canned.
Frequently asked questions
Why does this planner not give a canning time?
A safe process depends on the exact food, pack style, jar size, canner type, gauge and altitude. This tool counts batches and flags low-acid food in a water bath, but processing time and pressure must come from a tested recipe.