Ideal Egg Boiling Calculator

For a large egg (50g) taken from the fridge at sea level, hard boiling typically takes around 11–13 minutes. The exact time depends on your egg's size, starting temperature, and how high above sea level you are — all of which this calculator accounts for.

A medium-boiled (jammy) egg with a set white and soft, slightly runny yolk usually takes about 7–9 minutes for a large egg at sea level. Use this calculator with your specific egg size and altitude for a precise time.

Yes — water boils at a lower temperature at higher altitudes because of reduced atmospheric pressure. For example, at 2,000m water boils around 93°C instead of 100°C. This means the heat transfer to the egg is slower, so you need more time to reach the same internal temperature.

The formula is t = m^(2/3) × K × log((ywr × (T_egg − T_water)) / (T − T_water)), where m is egg mass, K is a thermal constant, T_egg is the starting egg temperature, T_water is the boiling point of water (adjusted for altitude), and T is the target internal temperature for your desired doneness.

Room-temperature eggs (around 20°C) cook faster and are less likely to crack when placed in boiling water. If you use fridge-cold eggs (around 4°C), add roughly 1–2 extra minutes to your boiling time — the calculator handles this automatically based on your input.

For a soft-boiled egg with a runny yolk, the yolk-white boundary should reach no more than about 63°C. A medium (jammy) yolk targets around 67°C, while a hard-boiled egg requires the centre to reach approximately 75°C.

Once your timer goes off, immediately transfer the eggs to a bowl of cold (or ice) water. This stops the cooking process by rapidly cooling the egg, preventing the greenish ring that can form around an overcooked yolk.

Absolutely. Larger eggs have more mass and a thicker albumen layer, so heat takes longer to reach the yolk. A Jumbo egg can take 2–3 minutes longer than a Small egg for the same doneness level, which is why this calculator uses egg size as a key input.