Why I Keep a Canning Altitude Chart on My Fridge
I've been canning for years, and I still keep an altitude chart taped to the inside of my pantry door. Not because I can't remember the numbers — because canning is the one place in cooking where "close enough" isn't a real option, and a quick glance beats relying on memory every single time. If you've never thought about altitude and canning before, here's why it matters more than most beginners realize, and why even experienced canners keep a chart on hand.
by The Home Hearth Co.
6/16/20263 min read
Why Altitude Changes Everything
Water boils at a lower temperature the higher you go in elevation. At sea level, water boils at 212°F. By 5,000 feet, that drops to around 203°F. It sounds like a small difference, but in food safety terms it's significant — the entire purpose of processing time in a water bath canner is reaching and holding a temperature hot enough to make the food safe, and a lower boiling point means less heat is doing the work in the same amount of time.
This is true for pressure canning too, just expressed differently. Instead of adjusting time, you adjust the pressure — more pressure raises the temperature inside the canner higher, compensating for the same boiling-point effect.
If you skip this adjustment and you live above 1,000 feet, you risk under-processing your food. The center of the jar may never reach a temperature hot enough to destroy harmful bacteria, even though everything looks completely normal from the outside.
The Two Adjustments, and Why They're Different
Water bath canning: add processing time. Since the water itself isn't getting as hot, you compensate by leaving the jars in longer.
Pressure canning: add pressure, not time. The tested processing time in a recipe is correct regardless of elevation — what changes is the PSI needed to reach 240°F at your specific altitude.
This trips up a lot of people, understandably — it seems like elevation should just mean "add more of whatever the recipe says," but the two methods solve the same problem in opposite ways. That's reason enough to keep a written reference handy rather than trying to remember which rule applies to which method.
A Real Example
Let's say you're water bath canning a tomato sauce that calls for 35 minutes of processing time at sea level. If you live at 3,000 feet, that processing time increases — exactly how much depends on the specific elevation bracket, but the takeaway is the same: the recipe's stated time is a sea-level number, and it's on you to adjust it for where you live.
For pressure canning, a recipe calling for 10 pounds of pressure on a weighted-gauge canner at sea level typically jumps to 15 pounds once you're above 1,000 feet — there's no fine-tuned middle option on most standard weighted gauges, so it's a clean jump rather than a gradual scale.
How to Find Your Elevation
If you don't already know your home's elevation, it only takes a minute to find. A quick search for your town's elevation, or any topographic/elevation-lookup tool online, will get you close enough for canning purposes — you don't need to be exact to the foot, just accurate to the nearest few hundred feet so you land in the correct adjustment bracket.
Write that number down somewhere permanent. You'll use it for the rest of your canning life unless you move.
Why a Chart Beats Memory
Canning happens in batches, often during the busiest, hottest weeks of the season — tomato harvest, a sudden glut of green beans, a meat sale you don't want to waste. In the middle of that, you're juggling hot jars, a ticking clock, and usually a kid or two underfoot. That's exactly the wrong moment to be trying to recall whether your specific elevation needs 15 pounds or 10, or whether you already accounted for the altitude adjustment in the time you started.
A printed chart removes the guesswork. You look, you confirm, you move on. It's a thirty-second check that protects an entire batch of food and the hours you put into it.
Keep One Where You'll Actually See It
The chart only works if it's somewhere you'll glance at it without having to search. Inside a pantry door, taped near the stove, tucked into the front of your canning supply box — wherever you're standing when you're prepping a batch.
My Canning Altitude Quick Reference Chart is built exactly for this — a clean, two-page printable covering both water bath time adjustments and pressure canning PSI adjustments by elevation, sized to print and post wherever you can it.
Get the Canning Altitude Quick Reference Chart →
New to canning and not sure which method you even need? Start with Water Bath vs. Pressure Canning: Which One Do You Actually Need?