The Kitchen Desk
Cook Carries Egg Up Mountain, Discovers Water Has Stopped Trying
Water boils cooler as you climb, so the seven minutes that produced a hard egg at the trailhead produces a raw one at the summit. The pot is not the problem. The sky is.
By R. Dunmore The Kitchen Desk 2026-08-15
Everyone who has boiled an egg somewhere high has a theory about what went wrong, and the theory is almost always that the egg overcooked. It is a reasonable guess. It is backwards: you will crack it expecting firm and receive liquid.
Boiling water is not a temperature you can rely on. It is whatever temperature water happens to boil at where you are standing, and where you are standing has a pressure. Go up, and the pressure falls, and the water gives up sooner. It is still boiling (vigorously, convincingly, exactly as it looks at sea level). It is simply doing so at a temperature that will no longer cook your egg on schedule.
What the sky is actually doing
At sea level water boils at 100 °C. The number falls from there:
| Where | Altitude | Water boils at |
|---|---|---|
| Sea level | 0 m | 100.0 °C |
| Denver | 1,609 m | 94.7 °C |
| Mount Hood | 3,429 m | 88.6 °C |
| Mount Whitney | 4,421 m | 85.3 °C |
| Kilimanjaro | 5,895 m | 80.3 °C |
| Everest summit | 8,849 m | 70.3 °C |
Turning the heat up does nothing. A pot cannot exceed the boiling point of what is in it; extra energy goes into making steam faster, not into making the water hotter. A furious boil and a lazy one are the same temperature; the furious one is only louder about it. This is the single most useful fact in this column and it is true at every altitude, including your kitchen.
Why the egg cares
An egg is not cooked by time. It is cooked by protein reaching a temperature — whites begin setting around 63 °C, yolks around 65 to 70 °C — and time is only the crude proxy we use because it is easier to count than to measure.
What drives the egg toward that temperature is the gap between the water and the target. At sea level a hard yolk at 70 °C sits 30 degrees below the water, and closes that gap in about eleven minutes. On Mount Hood the water is 88.6 °C, so the gap is 18.6 degrees, and everything slows accordingly.
The altitude egg timer
At 3,429 m water boils at 88.6 °C, not 100 °C. A hard egg needs about 17 min 45 s instead of 11 minutes.
Boiling point is physics and is accurate. The time is a first-order model, not a measurement — start checking a minute or two early.
The part where it stops working entirely
Keep climbing and the arithmetic runs out. At the summit of Everest water boils at 70.3 °C, which is roughly the temperature a yolk needs to set. The water is no longer meaningfully hotter than the target, so the egg is not slowly cooking. It is sitting in water that has nothing left to give it. You may wait as long as you like.
This is why pressure cookers are carried up mountains, and it is the whole idea behind them: raise the pressure, raise the boiling point, hand the water its temperature back. A sealed pot at altitude is not a convenience. It is the only way to reach temperatures the open air has taken away.
What The Kitchen Desk recommends
- Adjust before the hike, not during it. The calculator above is a starting point, not a stopwatch. Above the trailhead, start checking early and expect to add minutes.
- Bring them boiled. An egg cooked at 100 °C in your kitchen is fully cooked at any altitude you carry it to, and does not care about the pressure. The logistics answer to this problem is to do the cooking where physics is cooperating.
- Distrust the boil. Vigour is not heat. If a recipe says “rolling boil” it is describing a look, and at 3,000 m that look is 88 °C.
- Suspect the altitude before you suspect yourself. The recipe was written at somebody else’s elevation and did not say so.
What should exist
Recipes that state the altitude they were tested at, the way a tyre pressure states a temperature. “Boil for eleven minutes” is not an instruction. It is an instruction plus an unstated assumption about the weight of the atmosphere, and the assumption is wrong for a great many kitchens, including every kitchen in Denver, where it has been wrong for a hundred and fifty years without comment.
Boiling points computed from the ISA barometric formula and the Antoine equation for water; the figures above agree with published values to within a tenth of a degree. Setting temperatures for egg proteins are standard. The cooking-time adjustment is a first-order model (time scaling with the gap between water and setting temperature) and is presented as guidance, not measurement. It is the least certain number on this page and the one you should check with a spoon.
