Egg Doneness Temperature Chart — From 60°C Custard to 75°C Fully Set

Egg whites set at 62°C. Yolks set at 68°C. That 6-degree window is where every cooked egg variation lives — soft-boiled, sous vide poached, onsen, the runny-center hard-boiled, the custard-yolk Japanese ramen egg. Modernist Cuisine measured the protein denaturation curves. ChefSteps published the time-temperature charts. Serious Eats ran the home-kitchen tests. The data converges on a single map of egg textures by temperature.

This article walks through that map. With a sous-vide-style temperature controlled bath, you can reproduce any egg texture exactly. With a standard pot of boiling water plus a thermometer, you can hit 80% of the same textures.

The protein denaturation chart

Eggs have several distinct proteins, each setting at a different temperature. Modernist Cuisine published the cleanest version of this data in Volume 2:

Egg whites

Protein	Denaturation temp	Effect
Ovotransferrin	62°C (144°F)	First white begins to set, opaque
Conalbumin	64°C (147°F)	Major white setting, gel forms
Ovomucoid	70°C (158°F)	White becomes firmer
Ovalbumin	80°C (176°F)	White fully sets to opaque white

Egg yolks

Component	Denaturation temp	Effect
Lipoproteins	65°C (149°F)	Yolk thickens to custard
Phosvitin	68°C (154°F)	Yolk fully sets but jammy
Livetin	70°C (158°F)	Yolk firms to soft solid
Full set	75°C (167°F)	Yolk chalky, fully cooked

The key gap: yolk sets between 65-75°C, white between 62-80°C. The classic onsen egg (65-67°C) exploits this — yolk forms a thick custard, white is just barely set with a delicate texture. The classic hard-boiled egg sits at 100°C in the boiling water for 8-10 minutes — both proteins fully denature plus the green-ring reaction kicks in.

The full temperature map (sous vide style)

ChefSteps published a temperature/time grid. Here’s the consolidated version showing the most useful targets:

Temperature	Time	Result	Use
60°C (140°F)	45 min	Liquid yolk, soft white	Salmonella-pasteurized raw egg
62°C (143.5°F)	45 min	Custard yolk, sliding white	Onsen-style appetizer
64°C (147°F)	45 min	Custard yolk, just-set white	Classic Japanese onsen egg
65°C (149°F)	45 min	Thick custard yolk, set white	”63-degree egg” — restaurant standard
67°C (152.5°F)	45 min	Soft-set yolk, firm white	Ramen egg before peeling
70°C (158°F)	30 min	Set yolk, firm white	Sliced poached
75°C (167°F)	30 min	Hard yolk, firm white	Sous vide hard-boiled
100°C (212°F, boiling)	7 min	Soft yolk, firm white	Soft-boiled (boiling)
100°C (212°F, boiling)	10 min	Hard yolk, firm white	Hard-boiled (boiling)

The sous-vide method gives reproducible textures regardless of egg size, starting temperature, or cooking time variation. The boiling-water method depends on egg size and how cold the eggs are starting from — there’s a 1-2 minute spread between textures.

What goes wrong with traditional boiling

Two common failures, both temperature-related.

Problem 1: Overcooked white, undercooked yolk

A medium-large egg dropped into rolling boiling water (100°C) follows a temperature curve where the white reaches setting temperature in about 4 minutes, but the yolk takes 6-7 minutes to reach 65°C and 8-9 minutes to reach 70°C. The window between “white sets” and “yolk sets” is 4-5 minutes. Stop too early and the white is still slimy at the center; cook 30 seconds too long and the yolk overshoots into chalky territory.

Problem 2: The green ring

Above 70°C, sulfur from the white reacts with iron from the yolk to form ferrous sulfide (FeS). The reaction needs three things: heat above 70°C, time (the longer at 70°C+, the worse), and contact (sulfur from white reaches yolk via diffusion through the membrane). A 12-minute boil produces visible green-gray rings. A 60-minute sous vide at 75°C does not — the lower temperature keeps FeS formation slow enough that the ring doesn’t develop visibly even with much longer cook time.

How to reproduce sous-vide textures without a circulator

Two methods that get within 90% of the sous-vide result without buying an Anova or Joule.

Method A: The thermometer-and-saucepan approach

Heat 4 quarts of water to 75°C (167°F). Reduce heat to maintain 73-77°C — water should not bubble; small wisps of steam only. Add eggs straight from the fridge with a slotted spoon. Cook 18-20 minutes. Transfer to ice bath for 2 minutes to halt cooking. Result: yolk sets to firm but not chalky, white firm but not rubbery, no green ring. This approximates a 75°C/30-min sous vide reasonably well.

Method B: The cooler approach

Boil 4 quarts of water. Pour into a large insulated cooler. Stir until temperature drops to 67°C (152.5°F) — about 90 seconds. Add eggs. Close cooler. Wait 45 minutes. Transfer to ice bath. Result: 65°C onsen-style egg with thick custard yolk and just-set white. Temperature drift over 45 minutes is typically 2-3°C in a closed cooler — close enough to sous vide for most purposes.

Cook’s Illustrated’s traditional method

Cook’s Illustrated’s recipe for “perfect soft-boiled eggs” specifies:

• Bring 1 inch of water to a rolling boil in a saucepan with lid
• Add eggs straight from refrigerator using a slotted spoon
• Cover, reduce to simmer (low boil)
• 6.5 minutes for runny yolk, 8 minutes for jammy yolk, 10 minutes for hard-set
• Transfer immediately to ice bath, peel after 2 minutes

This works reliably because the rolling boil + simmer + lid + 1-inch shallow water depth combination lets the eggs cook in steam-saturated 95-97°C water (slightly below boiling), which gives a more forgiving 30-second window between texture stages. Cook’s Illustrated tested egg sizes (medium, large, extra large) and found the 6.5-8-10 minute reference holds within ±15 seconds across sizes for the same starting temperature (refrigerator-cold).

The salt and acid additions

Some recipes call for adding salt or vinegar to the cooking water. The science:

• Salt has minimal effect at typical 1% concentration. Some claim it helps eggs peel more easily — Modernist Cuisine tested this and found no measurable difference. The salt does help if a shell cracks during cooking by setting the leaking egg white quickly.
• Vinegar does help with cracked-shell eggs by setting white at lower temperature (acidic environment lowers white denaturation by 5-10°C). Add 1 tablespoon per quart of water if you’re worried about shell cracks.
• Baking soda makes peeling easier. Modernist Cuisine measured this — baking soda increases water alkalinity, which helps the inner shell membrane separate from the egg white. A 1/4 teaspoon per quart is the typical addition. The trade-off: alkaline water makes whites slightly looser-textured.

The peelability question

Old eggs peel more easily than fresh eggs. The reason: the air pocket at the egg’s wide end grows over time as moisture evaporates through the porous shell. Older eggs (2+ weeks old) have larger air pockets, which means the shell membrane separates from the white more easily after cooking. For hard-boiled eggs that need to look pretty, use eggs at least 7-10 days old. Very fresh farmer’s market eggs are notoriously hard to peel.

The cooking method also affects peelability. Steam-cooking (lower water level, lid on) produces eggs that peel more reliably than boiling. The reason isn’t fully understood — current best theory is that steam cooks the white with less direct convection, leaving a thinner adherence layer between shell and white.

The bottom line

Two pieces of equipment unlock most of the egg map:

1. An instant-read thermometer. This is the same tool that fixes pasta water salt, steak doneness, and fish poaching. It costs $35-100 and changes far more than just eggs.
2. A digital scale. For the salt-the-water recipes that come up, weight beats volume by 2-3x accuracy.

With these, the boiling-water method gets reliable results across the whole 60-100°C range. Without them, you’re guessing — and egg cooking is a 30-second game where guessing produces consistently mediocre results.

Pick the temperature for the texture you want, hit it precisely, and the egg cooks itself.

Recommended tools for hitting target egg temperatures

If you cook eggs by feel today, switching to thermometer-verified temperatures eliminates almost all overcooking. Three thermometers consistently rank as the most reliable picks for sub-second readings and accurate calibration:

For egg work specifically, any of these will get you within 1 deg F of target — the Thermapen ONE wins on speed, the TP19H wins on price, and the Javelin PRO Duo offers the best balance for home cooks who care about both.