Carry-over cooking: why eggs keep cooking after the pot
When you lift an egg out of boiling water, its centre is not done cooking. The white near the shell is almost at 100 °C, while the middle of the yolk is much cooler, and heat keeps flowing inwards for minutes. Good boiling times plan for this.
How much the centre keeps heating
For a medium egg (58 g) straight from the fridge, cooked to a jammy yolk. The boiling time is chosen so that the yolk centre peaks at the same temperature whichever way you cool it.
| Cooling | Boil for | Yolk centre when removed | Yolk centre peak | Keeps heating for |
|---|---|---|---|---|
| Ice bath | 8:36 | 49.2 °C (120.6 °F) | 66.0 °C (150.9 °F) | 3:25 |
| Water at room temperature | 8:22 | 47.4 °C (117.3 °F) | 66.0 °C (150.8 °F) | 3:50 |
| Air at room temperature | 5:39 | 24.5 °C (76.1 °F) | 66.0 °C (150.8 °F) | 9:22 |
In an ice bath the yolk centre still climbs about 17 °C after the egg leaves the water. Left on the counter it climbs about 41 °C, so the egg has to come out much earlier: 5:39 instead of 8:36.
Why it happens
Heat moves through an egg slowly, by conduction. While the egg boils, the outside heats up first and the centre lags behind. Take the egg out and the hot outer layers are still warmer than the centre, so heat keeps flowing inwards until the inside and the outside even out. Cooling the shell quickly, in iced water, cuts that flow short; cooling it slowly in air lets much more of the stored heat reach the yolk.
What it means in your kitchen
- An ice bath gives the most repeatable result, because it stops the outside quickly and the carry-over is small.
- If you skip the cooling, shorten the boil. An egg left to cool in its shell finishes cooking on the counter.
- Leave it in the cold until the centre stops heating. Taking it out too early lets the carry-over continue.
Open the calculator: its timer includes the cooling step and shows the yolk temperature live in Chef mode.