Calculates the exact boiling time for the perfect egg based on size, starting temperature, and altitude. Science-backed for precise consistency.
Please enter a valid weight in grams.
Higher altitudes lower the boiling point, requiring more cooking time.
Soft-boiled: Jammy texture
Prepare your ice bath while you wait!
Cooking an egg isn't just art; it's physics. We use the Charles Williams formula, a heat diffusion equation derived at the University of Exeter. It calculates precisely how long it takes heat to travel through the shell and white to reach the yolk center.
The magic lies in the temperature gap. Egg whites coagulate (set) around 62°C, while yolks remain liquid until about 65°C. Our calculator balances your egg's mass, starting temperature, and atmospheric pressure (altitude) to hit that narrow window perfectly.
This is usually "thermal shock"—dropping a cold egg into boiling water. To prevent it, prick the wider end of the egg with a pin to release air, or use room-temperature eggs.
That's ferrous sulfide. It forms when you overcook the egg, causing iron in the yolk to react with sulfur in the white. Stick to the timer above to avoid it!
Bring a pot of water to a rolling boil. There should be enough water to completely submerge the eggs by at least an inch.
Using a slotted spoon, gently lower your eggs into the boiling water. Do not drop them. Start the timer immediately.
Lower the heat slightly to maintain a gentle boil. Too violent, and they might crack against the pot.
The moment the timer beeps, transfer eggs immediately to a bowl of ice water for 3 minutes. This stops the cooking and shrinks the egg slightly inside the shell.
Disclaimer: Consuming raw or undercooked eggs may increase your risk of foodborne illness, especially if you have certain medical conditions. Formula based on data from the University of Exeter.