How to Adjust Canning for Altitude
At higher altitudes, water boils at a lower temperature, so canning needs adjustment: pressure canners use higher pressure, and water-bath canners use longer processing times. Always use the altitude-adjusted figures from a tested recipe for your elevation.
Altitude is the canning variable people forget, and it genuinely affects safety. The same recipe processed at sea level and on a mountain do not deliver the same heat, so tested recipes tell you how to adjust.
Why it matters
Water boils at a lower temperature as altitude rises. Since canning relies on reaching a specific temperature, the same time or pressure delivers less heat higher up, so you must compensate to stay safe.
How each method adjusts
| Method | Altitude adjustment |
|---|---|
| Pressure canning | Increase the pressure |
| Water-bath canning | Increase the processing time |
Related: how to pressure can, how to water-bath can, and is home canning safe?
- 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
Why does altitude affect canning?
Water boils cooler at higher elevations, so the same time or pressure delivers less heat. Adjusting compensates, ensuring food reaches a safe temperature.
How do I adjust canning for my altitude?
Use the altitude tables in tested recipes: pressure canners increase the pressure, water-bath canners increase the time. Find your elevation and use its specified figures.