Egg Boiling Time Calculator
This egg boiling time calculator tells you how long an egg should stay in boiling water for a soft, medium or hard yolk, based on the egg's weight, its starting temperature and your altitude.
Example: Doneness: Medium (jammy yolk) · Egg weight 57 g · Starting temperature: Straight from the fridge (5 °C / 41 °F) · Altitude above sea level 0 m → Boiling time: Medium: 5 min 15 sec. Source: University of Exeter – The Science of Boiling an Egg (Williams-Formel). Updated: .
How it is calculated
A medium egg (57 g) from the fridge needs about 4½ minutes for a runny yolk, and a little over a minute less at room temperature. The calculator also factors in weight, doneness and altitude.
How it is calculated
It uses the formula by physicist Charles Williams of the University of Exeter: cooking time grows with the egg's mass to the power of two thirds and with the logarithm of the ratio of temperature differences between egg, water and target. The prefactor is 0.451 minutes per g^(2/3). Egg white starts to set at about 63 °C, so that yolk temperature gives a soft egg. For medium and hard the tool uses 67 °C and 80 °C as targets, and the table shows them openly.
What changes the time
- Size: an extra large egg takes about a minute longer than a small one.
- Starting temperature: fridge eggs take longer than eggs from the counter.
- Altitude: in the mountains water boils at a lower temperature, so the egg cooks more slowly. At 1,500 m it is only about 95 °C.
Tip: lower eggs gently into boiling water with a spoon and cool them in cold water as soon as time is up. More kitchen help: the cooking converter, an online timer for counting down and the pizza dough calculator.
Frequently asked questions
How long do you boil a soft-boiled egg?
A medium egg (57 g) straight from the fridge needs about 4½ minutes in rolling boiling water for a runny yolk, a little over 3 minutes if it starts at room temperature.
How long do you boil a hard-boiled egg?
A medium egg from the fridge needs roughly 8 to 9 minutes for a set yolk according to the model. Cool it in cold water afterwards so it does not keep cooking.
Is the time counted from putting the egg in or from boiling?
From the moment the egg goes into water that is already boiling. If the egg starts in cold water, the time changes by several minutes depending on your stove.
Why do eggs take longer at altitude?
Water boils at a lower temperature when air pressure falls, about 1 °C less per 300 m. The egg receives less heat and cooks more slowly.
How accurate is the calculated time?
It is a physical model that treats the egg as a sphere. In practice pot, water volume and egg shape shift it by about half a minute, so try the first egg and adjust.
Sources and legal basis
- University of Exeter – The Science of Boiling an Egg (Williams-Formel)
- USDA FSIS – High Altitude Cooking (boiling point drops with altitude)
As of: · Editorial policy
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