Ideal Egg Boiling Calculator
Find the perfect boiling time for your eggs based on their weight, starting temperature, your desired doneness, and even your cooking altitude.
How This Calculator Works
Boiling an egg well is really a heat-transfer problem: heat has to travel from the boiling water, through the shell, into the white, and finally to the yolk at the center. The bigger the egg, the longer that journey takes. Cooking time scales with the egg’s weight raised to the two-thirds power, which reflects how heat penetrates a roughly spherical object — this is the same scaling relationship used in classic egg-cooking physics research.
What the Inputs Change
- Egg weight: a small 45g egg cooks noticeably faster than a large 70g egg.
- Starting temperature: an egg taken straight from the fridge needs a bit more time than one that has warmed to room temperature first.
- Altitude: water boils at a lower temperature as altitude increases (roughly 1°C cooler for every 300 meters of elevation), so at higher altitudes eggs need extra time to reach the same doneness.
- Doneness: soft-boiled targets a runny yolk, medium aims for a jammy center, and hard-boiled fully sets the yolk.
This calculator is intended for general kitchen planning purposes. Actual results can vary slightly with your stove, pot, water volume, and egg freshness, so treat the result as a strong starting point and adjust to taste.