Process Adjustments at High Altitudes
From "The Complete Guide to Home Canning"

To determine the elevation at your location click on the Topozone elevation database
http://www.topozone.com/findplace.asp

Using process time intended for canning food at sea level may result in spoilage if you live at altitudes of 1,000 feet or more. Water boils at lower temperatures as altitude increases. Lower boiling temperatures are less effective for killing bacteria. Increasing the process time or canner pressure compensates for lower boiling temperatures. Therefore, when you use the guides, select the proper processing time or canner pressure for the altitude where you live.

Pounds of Pressure
Boiling point of water (F)
Boiling point of water (C)

Process time
Dial Gauge
(min)

Process Time
Weighted Gauge
(min)
  Sea Level
212.0
100.0
10
10
  1,000 ft
210.2
99.01
10 1/2
15
  2,000 ft
208.5
98.03
11
15
  3,000 ft
206.7
97.05
11 1/2
15
  4,000 ft
204.9
96.08
12
15
  5,000 ft
203.2
95.12
12 1/2
15
  6,000 ft
201.5
94.16
13
15
  7,000 ft
199.8
93.21
13 1/2
15
  8,000 ft
198.1
92.26
14
15
  9,000 ft
196.4
91.32
14 1/2
15
 10,000 ft
194.7
90.39
15
15
  • Actual boiling points are based on barometric pressure which is a function of altitude and changes with the weather conditions each day.
  • To determine your real-time barometric pressure and the exact boiling point of water in your location visit http://www.biggreenegg.com/boilingPoint.htm

To compute the air pressure (p) for each altitude, the formula used is p = poe-ay
where
p = pressure in Pascals (Pa)
po = pressure at sea level = 1.013x105 Pa
a = 1.16x10-4 m-1
y = altitude (m)
(see Halliday & Resnick, Physics pp. 374-375, John Wiley & Sons, Inc. (1978))
This formula assumes temperature and acceleration of gravity are constant over the range of altitudes. T = 20 C, and g = 9.8 m/s2.