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.