Egg guides

Practical answers to the questions behind a good boiled egg. Every time and temperature on these pages comes from the same heat-transfer model as the calculator.

• How long to boil an egg: times by size and doneness

  Boiling times for small to extra-large eggs, from runny to hard-boiled, straight from the fridge or at room temperature, calculated from the physics of heat.

• Boiling eggs at high altitude

  Water boils below 100 °C in the mountains, so eggs take longer. Boiling points and egg times from sea level to 4,000 m.

• Carry-over cooking: why eggs keep cooking after the pot

  An egg's centre keeps heating for minutes after it leaves the water. How much depends on how you cool it: ice bath, cold water or air.

• Fridge or room temperature eggs?

  How much a cold egg changes the boiling time, from runny to hard-boiled, and why starting temperature matters more than you think.