Egg Boiling Timer

How to use this egg timer

1. Pick the yolk you want. The six settings run from a dippy egg you eat with a spoon to a firm one you can grate. The swatch on each button is roughly what the cut face looks like.
2. Say what size your eggs are. This is the input almost nobody adjusts, and it is worth nearly two minutes between a small egg and a jumbo. It is printed on the carton.
3. Fridge or counter. An egg that has been sitting out finishes about a minute ahead of one straight from the fridge.
4. Enter your elevation. If you are anywhere above about 2,000 feet, this is the difference between a set yolk and a runny one, and it is the part every other egg timer waves away.
5. Boil the water first, then start the timer. Lower the eggs into water that is already boiling, hit start, and drop the heat to a bare simmer. When it beeps, straight into ice water for fifteen minutes.

Why this egg timer is different

Every egg timer you can find is the same object: three buttons marked soft, medium and hard, wired to three fixed numbers. Those numbers are correct for exactly one egg in one kitchen, and the timer has no idea whether that is your egg or your kitchen.

• It knows how big your egg is. Heating time for a sphere scales with mass to the two-thirds power, so a 70.9 g jumbo genuinely needs about 1:45 longer than a 42.5 g small for the same yolk. We use the USDA weight classes and the actual scaling law, not a rounding.
• It computes your boiling point instead of guessing at it. Water does not boil at 212°F in Denver, it boils at 202°F, and a hard-boiled egg there needs 12:50 rather than 11:00. The elevation correction comes from the same steam-table equation used in engineering, not from "add a minute or two".
• It knows when boiling is the wrong method. Above 5,000 feet it hands you Colorado State University Extension's covered-standing method instead, because that is what the extension service actually recommends up there. Above 10,000 feet it tells you to steam or pressure-cook.
• It shows its work. Under every result is the breakdown: the published base time, what your egg size did to it, what your elevation did to it, and what starting temperature did. No other page on this topic shows a derivation at all.
• It times the ice bath too. Every source agrees the ice bath is what stops the cooking and makes eggs peel; no timer counts it. This one rolls straight into it when the boil finishes.
• The math is cited and tested on every build. Formula, sources, and a fixture suite that checks our boiling points against published tables from sea level to 12,000 feet and reproduces the published doneness chart exactly. If it drifts, the build fails.

How it works (the math)

One published starting point and three adjustments.

time = base(doneness) x sizeFactor x altitudeFactor + startOffset

1. The base time is the published figure for a large egg taken straight from the fridge and lowered into already-boiling water at sea level: 4 minutes dippy, 6 soft, 8 jammy, 9 medium, 11 hard, 12 firm. Kenji López-Alt's testing for Serious Eats gives six minutes for soft and eleven for hard; RecipeTin Eats gives six for runny, eight for soft-boiled and ten for classic hard. The two ladders agree at the soft end and bracket the hard end, and we take the eleven-minute figure because it is chosen specifically to stop short of the grey sulphur ring.

2. Egg size is the one part of this that is exact:

sizeFactor = (mass / 56.7 g) ^ (2/3)

Heat has to diffuse from the shell to the centre, and for a sphere the time that takes scales with mass to the two-thirds power. This comes straight from the egg-cooking model published by Peter Barham and Charles Williams. The masses are the USDA consumer weight classes: 42.5 g small, 49.6 g medium, 56.7 g large, 63.8 g extra-large, 70.9 g jumbo.

3. Elevation works through your boiling point, in two steps:

p  = 101325 x (1 - 2.25577e-5 x h) ^ 5.25588      (US Standard Atmosphere, h in metres)
Tw = IAPWS-IF97 Region 4 backward equation Ts(p)

Water boils when its vapour pressure matches the air pressing down on it, so as the air thins the boiling point falls, by roughly 1 °F every 500 feet near sea level. Cooler water means a longer cook, and the size of that penalty depends on how hot you were trying to get the yolk. We scale the time by the ratio of the Barham–Williams heating term at your boiling point to the same term at sea level:

f(Tw) = ln[ 0.76 x (Tw - 4) / (Tw - Tyolk) ]
altitudeFactor = f(Tw_local) / f(Tw_sea_level)

Why a ratio and not a straight prediction. Run that model on its own and it puts a 70 °C yolk centre at about six minutes, which disagrees with every kitchen chart ever published. Used as a ratio it behaves: sweeping the yolk target from 70 to 80 °C moves the Denver answer by under thirty seconds. So the physics is used only for the thing it models well, which is how the boiling point changes the time, and the absolute numbers stay with the published chart. That is also why the sea-level reference is IAPWS's 99.974 °C rather than a round 100, so at sea level the factor is exactly one and the published times come back untouched.

4. Starting temperature takes a flat minute off for a room-temperature egg. This one is deliberately not derived: the same equation predicts a two-to-three minute saving, which is far more than any test kitchen reports, so the kitchen number wins and the model sits this one out. Limitation: your pot, your burner and how many eggs you crowd in all matter and none of them are inputs here. Cut one open the first time you use a new setting.

Three worked examples

A soft-boiled large egg at sea level

The default, and the case every chart is implicitly written for. Large egg, fridge-cold, into boiling water: 6:00, then ice for fifteen minutes. Nothing is adjusted because nothing needs to be, which is exactly why the six-minute rule became the rule.

Hard-boiled jumbo eggs in Denver

Now both corrections bite at once. A jumbo egg is 25 percent heavier than a large, which adds 1:46, and at 5,280 feet water tops out at 202.3°F, which adds another 2:06. An 11:00 egg becomes 14:50. Follow a carton-back timing here and you get a wet centre and no idea why. If you are hard-boiling a batch for the week, a rice cooker with a steam tray holds a steadier temperature than a pan on a high-altitude burner does.

Jammy eggs for a rice bowl, medium eggs, steamed

A jammy egg has the narrowest window on the ladder, so the two variables worth getting right are size and how you get them out of the pot. Medium eggs at sea level land at 7:20 rather than the 8:00 you would set for large. Steam them rather than boil: it is the same clock, because steam sits at the same saturation temperature, but far fewer shells crack on the way in. They go on top of rice from the rice cooker, or over fried rice from a carbon-steel wok, which is where a jammy yolk earns its keep.

Frequently asked questions

How long do you boil eggs for?

For a large egg taken straight from the fridge and lowered into already-boiling water at sea level: 6 minutes for a runny soft-boiled yolk, 8 minutes for a jammy one, 11 minutes for hard-boiled, and 12 if you want it firm enough to slice thin. Push past about 14 and the white turns rubbery and the yolk greys at the edge. Those numbers move with egg size and elevation, which is what the timer above is for.

Do you put eggs in boiling water or cold water first?

Boiling water, and it is not close. In Kenji López-Alt's testing, eggs started in already-boiling water or in a steamer peeled cleanly more than 90 percent of the time, while eggs started in cold water managed just over 50 percent, even at two weeks old. Starting cold also means your clock is measuring your burner rather than your egg, so the same timing gives you a different result on a different stove. The one place cold-start still wins is high elevation, where Colorado State University Extension recommends a covered, off-the-heat standing method instead.

Does altitude change how long to boil eggs?

Yes, and considerably more than most people expect. At 5,280 feet water boils at 202°F instead of 212°F, so a hard-boiled egg needs about 12:50 rather than 11:00; at 10,000 feet it is closer to 15:00. The USDA is explicit that the fix is time, not heat: turning the burner up cannot make water hotter than its own boiling point, it just boils it away faster. Above 5,000 feet, CSU Extension's method is to simmer 5 minutes, then stand covered off the heat for 15 minutes (20 for extra-large).

Does egg size really change the timing?

More than any other variable you control. Heating time scales with mass to the two-thirds power, so going from a medium egg to a jumbo is roughly a two and a half minute swing on a hard-boiled egg and about ninety seconds on a soft one. Since a soft-boiled egg only has a couple of minutes of usable window in the first place, a jumbo timed like a large comes out visibly underdone. Check the carton: the size is printed on it.

Why do my hard-boiled eggs have a grey ring around the yolk?

That ring is iron sulphide, and it means overcooking, not a bad egg. Above about 180°F the sulphur in the white and the iron in the yolk react at the boundary between them, which is why it appears as a ring rather than throughout. Two things prevent it: stop at 11 minutes rather than 15, and get the eggs into ice water the moment the timer goes so they stop carrying on cooking in their own heat. It is harmless to eat, it just looks and tastes worse.

Related tools

• Rice to Water Ratio — the other thing on the stove when a jammy egg is going on top.
• Browse all free kitchen tools by Nora →

Gear that makes it repeatable

Knowing the number is half of it. Hitting it the same way every time is the other half.

• Something to get every egg out at once. A soft-boiled egg has a two-minute window, and fishing them out one at a time with a slotted spoon spends most of it. A spider skimmer or a steamer basket lifts the whole batch in one movement.
• A pan that recovers fast. Six cold eggs dropped into a thin pan knock the water off the boil for a minute, and that minute is not in anyone's timing chart. A small, heavy-based saucepan comes back quickly.
• A rice cooker if you batch-cook. Most models steam eggs on the tray while rice cooks underneath, which is a genuinely good use of a machine you already own. Our best rice cookers guide covers which ones hold temperature properly.
• A food processor for what comes after. A dozen hard-boiled eggs is usually a step towards egg salad or deviled eggs. See our best food processors for the bowls that handle small, wet batches without turning them to paste.

Sources & methodology

• Serious Eats / J. Kenji López-Alt — The Food Lab: How to Make Perfect Hard-Boiled Eggs — the doneness times, the egg-protein set temperatures, the boiling-vs-cold-start peeling data, and the fifteen-minute ice bath.
• RecipeTin Eats — How to boil eggs — the second published doneness ladder used to bracket ours.
• USDA AMS — Shell Egg Grades and Standards — the consumer weight classes behind every egg mass in the tool.
• USDA FSIS — High Altitude Cooking — "do not increase the heat, just increase the cooking time."
• Colorado State University Extension — High Elevation Hard-Cooked Eggs — the covered standing method surfaced above 5,000 feet.
• IAPWS R7-97 — Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam — the Region 4 saturation-temperature equation behind the boiling point.
• Peter Barham, The Science of Cooking (Springer, 2001), and C. D. H. Williams, Towards the Perfect Soft Boiled Egg, University of Exeter — the mass^2/3 scaling and the heating term.

Doneness times are the published figures for a large, fridge-cold egg lowered into already-boiling water at sea level. Egg size scales them by mass^2/3 using USDA weight classes. The elevation correction is the ratio of the Barham–Williams heating term at your local boiling point to the same term at sea level, with the boiling point computed from the US Standard Atmosphere 1976 troposphere equation and the IAPWS-IF97 Region 4 backward equation. Room-temperature eggs take a flat published minute off; the physical model is deliberately not used there because it overstates the effect. A fixture test asserts the IAPWS reference point, thirteen published altitude/boiling-point pairs, all six chart times reproduced exactly, both size sweeps, steam-equals-boil, monotonicity in all three levers, and 360 input combinations for finiteness on every build. Reviewed by Nora Whitfield, CIA Culinary Arts, ServSafe Certified. About Nora · Last reviewed September 2, 2026.

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