Egg Boiling Calculator

Enter your egg size, doneness preference (soft, medium, or hard), egg starting temperature, and altitude to get the exact boiling time for your perfect egg. The Egg Boiling Calculator uses the physics-based formula accounting for egg mass, water boiling temperature at elevation, and your target yolk consistency — giving you time at boil and total cooking time in minutes and seconds.

Select the size of your egg (US standard grading)

Soft: yolk-white boundary ≤65°C. Hard: yolk core reaches 70°C.

°C

Fridge eggs ~4°C, room temperature eggs ~20°C

m

Water boils at lower temperatures at higher altitudes, increasing cook time

Results

Time at Boil

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Total Cooking Time (incl. bringing to boil)

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Water Boiling Point at Your Altitude

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Target Egg Core Temperature

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Cooking Time Breakdown

Frequently Asked Questions

How long does it take to hard boil an egg?

For a US Large egg (57g) starting from the fridge at sea level, a hard boiled egg typically needs around 10–12 minutes once the water is boiling. Larger eggs, colder starting temperatures, or higher altitudes all increase this time. Use the calculator above for a precise result tailored to your conditions.

How long does it take to medium boil an egg?

A medium boiled egg — with a jammy, partially set yolk — generally takes 6–8 minutes at boil for a standard large egg at sea level. The exact time depends on egg size, whether it came from the fridge or room temperature, and your altitude.

Do eggs boil differently at different altitudes?

Yes — water boils at a lower temperature at higher altitudes (e.g., about 90°C at 3,000m vs 100°C at sea level). Because the water is cooler, it takes longer to cook the egg to the same internal temperature. The calculator accounts for this using the altitude-adjusted boiling point formula.

Should I use fridge-cold or room-temperature eggs?

Room-temperature eggs cook faster because they start closer to the target core temperature. Fridge eggs (around 4°C) need extra time — typically 1–2 minutes more depending on egg size. Using room-temperature eggs also reduces the chance of cracking when placed in hot water.

What temperature should a soft boiled egg reach?

For a soft boiled egg, the yolk-white boundary should reach no more than 65°C (149°F) — the yolk remains liquid and runny while the white is just set. For a hard boiled egg, the yolk core should reach around 70°C (158°F) so it is fully cooked and firm.

What is the science behind the egg boiling formula?

The formula t = m^(2/3) × K × log((ywr × (T_egg − T_water)) / (T − T_water)) models heat transfer from the boiling water through the egg white to the yolk. It accounts for egg mass (m), the thermal properties constant (K), the starting egg temperature, and the water boiling temperature (which varies with altitude).

How do I stop my eggs from cracking while boiling?

Add half a teaspoon of salt or a dash of vinegar to the water to help seal any minor cracks. Avoid using eggs straight from the fridge — let them approach room temperature first, or lower them gently into simmering (not aggressively boiling) water. After cooking, rinse with cold water to stop the cooking process.

How do I peel a hard boiled egg easily?

The easiest method is to immediately transfer cooked eggs to an ice bath for 5–10 minutes. The rapid cooling causes the egg to contract slightly from the shell. Then gently crack the shell all over on a hard surface, roll it between your palms, and peel starting from the wider end where the air pocket sits.

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