Perfect Egg Timing Calculator

The perfect boiled egg is a matter of precise timing and temperature control. The proteins in egg whites and yolks coagulate at specific temperatures, and controlling how much heat penetrates the egg determines whether you get a runny yolk, a jammy center, or a fully cooked firm yolk.

Egg Protein Temperature Reference

The white and the yolk set at different temperatures, and that difference is the whole reason a soft-boiled egg is possible at all. In order:

• 63°C (145°F): egg white begins to set, slowly
• 70°C (158°F): yolk begins to thicken
• 71°C (160°F): egg white is fully set but still tender
• 77°C (170°F): yolk is fully solid but still moist
• 85°C and above (185°F and above): yolk turns crumbly and a gray-green ring can form

Note how close 70 and 71 sit. The white finishes setting almost exactly where the yolk starts, which is why the window between “runny yolk” and “jammy yolk” is about ninety seconds of boiling and not a comfortable margin.

Why Starting Temperature Matters

Eggs taken straight from the refrigerator (typically 4°C / 39°F) take 1 to 2 minutes longer than eggs at room temperature (20°C / 68°F). This calculator adds 90 seconds for a cold start.

Altitude Effects

At altitude water boils cooler, so the egg cooks more slowly. At 2,000 m (6,560 ft) water boils at about 93°C (199°F), and eggs need roughly 1 extra minute per 1,000 m above sea level.
The same physics is behind the potato timings: anything cooked in boiling water is affected, and anything cooked in an oven is not, because an oven holds whatever temperature you set it to regardless of the air pressure outside.

Cooking Time Guidelines (Large Eggs, Sea Level)

Ice Bath After Cooking

Always move cooked eggs straight into ice water for 5 minutes. It stops the cooking exactly where you wanted it and makes peeling far easier. Skip it and carryover heat keeps cooking the egg for another 1 to 2 minutes, which is enough to turn a jammy yolk chalky.