Boiling eggs at high altitude
Hard · Large · Fridge
Get the ice bath ready. Yolks keep setting after the pan comes off.
Duck, quail, altitude and more
Water boils below 100 °C at altitude, so eggs take longer. Adjusted boiling times for Denver, Mexico City, Bogotá, Cusco and any elevation you enter.
Why altitude changes egg timing
Water boils when its vapour pressure matches the air pressure around it. Higher up there is less air pressing down, so it boils sooner, and cooler. At sea level that is 100 °C; in Denver it is 94.7 °C, and in La Paz only 88.0 °C.
A cooler pan drives heat into the egg more slowly, so everything takes longer. Turning the hob up does nothing: water cannot get hotter than its boiling point, no matter how hard it boils.
| City | Altitude | Water boils at | Soft | Hard |
|---|---|---|---|---|
| Madrid, Spain | 667 m | 97.8 °C | 6 min 15 sec | 13 min 30 sec |
| Calgary, Canada | 1,045 m | 96.6 °C | 6 min 30 sec | 14 min 15 sec |
| Salt Lake City, USA | 1,288 m | 95.7 °C | 6 min 45 sec | 14 min 45 sec |
| Denver, USA | 1,609 m | 94.7 °C | 6 min 45 sec | 15 min 15 sec |
| Johannesburg, South Africa | 1,753 m | 94.2 °C | 7 min | 15 min 30 sec |
| Mexico City, Mexico | 2,240 m | 92.6 °C | 7 min 15 sec | 16 min 45 sec |
| Addis Ababa, Ethiopia | 2,355 m | 92.2 °C | 7 min 15 sec | 17 min |
| Bogotá, Colombia | 2,640 m | 91.3 °C | 7 min 30 sec | 17 min 45 sec |
| Cusco, Peru | 3,399 m | 88.8 °C | 8 min | 20 min 15 sec |
| La Paz, Bolivia | 3,640 m | 88.0 °C | 8 min 15 sec | 21 min 15 sec |
Is there a height where it stops working?
Yes, but it is higher than almost anyone lives. A fully hard-set yolk needs to reach about 82 °C, and water stops boiling that hot at roughly 5,450 m. Above that the egg will never hard-set however long you leave it in. For comparison, La Rinconada in Peru, the highest permanent settlement on earth, sits at about 5,100 m.
Everywhere in the table above, hard-boiling still works. It just takes longer, 21 minutes in La Paz against 12 and a half at sea level.
Other boiling times
Egg guides
Egg times come from the thermal-diffusion equation for a spherical egg published by Charles D. H. Williams (University of Exeter), calibrated so a large fridge-cold egg at sea level matches the times cooks actually use. Size, starting temperature and altitude then follow from the physics. Treat the result as a very good starting point, not a guarantee, because pans, hobs and eggs all vary.