Egg Boiling Time Calculator — Soft, Medium or Hard Boiled
Get the scientifically calculated boiling time for your egg based on its mass, starting temperature and preferred doneness — no guesswork needed.
g
°C
°C
Desired doneness
Place egg into already-boiling water
- 1
Mass factor M^(2/3)
60^(2/3) = 15.3262 - 2
Log argument
0.76 × (100 − 4) ÷ (100 − 70) = 2.432Ratio of available heat to heat still needed. - 3
Natural log
ln(2.432) = 0.8887 - 4
Time in seconds
27.05 × 15.3262 × 0.8887 = 368.4 - 5
Boiling time
368.4 ÷ 60 = 6.1
How does this calculator work?
Boiling time t ≈ 27 × M^(2/3) × ln(0.76 × (T_water − T_start) / (T_water − T_yolk)) seconds (Williams, 2002). A 60 g egg from the fridge (4 °C) in 100 °C water takes ≈ 5 min for runny yolk, ≈ 6 min for jammy, and ≈ 11 min for fully hard boiled.
Formula
How this is calculated
The calculation uses the heat-conduction model published by C. D. H. Williams (2002), which treats the egg as a uniform sphere whose thermal properties match egg albumen (white). The formula t = K × M^(2/3) × ln(0.76 × (T_w − T_0) / (T_w − T_y)) estimates the time for the yolk centre to reach temperature T_y when the egg is dropped into water already at T_w. The constant K ≈ 27.05 s/g^(2/3) bundles the albumen specific heat (3.7 J/g·K), density (1.038 g/cm³), and thermal conductivity (5.4 × 10⁻³ W/cm·K). The factor 0.76 corrects for the oval shape and shell resistance. Mass M enters as M^(2/3) because heat flows through the surface while volume determines how much to heat — a 75 g egg takes about (75/60)^(2/3) ≈ 1.16× longer than a 60 g one.
Doneness presets set the target yolk temperature: soft-boiled (runny, 63 °C), medium or jammy (70 °C), and hard-boiled (fully set, 85 °C). A fridge-cold egg (4 °C) takes noticeably longer than a room-temperature one because more heat must be added to bridge the larger temperature gap. At altitude, water boils below 100 °C — enter the actual boiling point for your location and the formula adjusts automatically.
The model is an approximation: expect accuracy of roughly ± 30–60 seconds. It assumes you drop the egg into already-boiling water; if you start in cold water add 3–4 minutes. Real eggs vary in composition and geometry, and coagulation changes thermal conductivity slightly during cooking. Treat the result as a starting estimate and adjust to taste.
Frequently asked questions
The formula includes the starting temperature T_0. A fridge egg at 4 °C has a larger temperature gap to bridge to reach the target yolk temperature, requiring more heat — typically 1–2 minutes longer than a room-temperature egg for the same doneness.
At higher altitudes, water boils below 100 °C (≈ 95 °C at 1 600 m, ≈ 87 °C at 3 000 m). A cooler water bath drives heat into the egg more slowly, so boiling takes longer. Enter the actual boiling point of water at your altitude for an adjusted result.
The formula assumes you place the egg into already-boiling water. If you start with cold water and bring it to a boil, add approximately 3–4 minutes to the calculated time — the egg heats gradually as the water temperature rises.
Also known as
TG we-Calculate Editorial Team. (2026). Egg Boiling Time Calculator — Soft, Medium or Hard Boiled [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/egg-boiling-calculator
TG we-Calculate Editorial Team. "Egg Boiling Time Calculator — Soft, Medium or Hard Boiled." TG we-Calculate. 2026. https://we-calculate.com/calculator/egg-boiling-calculator.
TG we-Calculate Editorial Team, "Egg Boiling Time Calculator — Soft, Medium or Hard Boiled," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/egg-boiling-calculator
@misc{wecalculate_egg_boiling_calculator, title = {Egg Boiling Time Calculator — Soft, Medium or Hard Boiled}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/egg-boiling-calculator}}, year = {2026}, note = {TG we-Calculate} }
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