How to Make Jammy Eggs

Pull a large egg from a rolling boil at 6 minutes 30 seconds, plunge it into ice water, and crack the shell. The white is fully set. The yolk holds its shape but spreads like soft butter under pressure. That is a jammy egg. It is the sweet spot between a runny soft-boiled yolk and a fully firm hard-cooked yolk, and it is the base for ramen eggs, ajitsuke tamago, and any dish where you want a yolk that coats noodles instead of dripping off them.

Two things trip up first-timers: the exact minute count, and the peeling. You get both here, sourced from lab tests and professional kitchens, not from a generic chart that ignores egg size and altitude.

Times for a Large Egg at Sea Level

Jammy egg time sits between soft-boiled and hard-cooked. For a large egg started in boiling water at sea level:

Soft-boiled: 6 minutes. White set, yolk completely liquid.
Jammy (medium-boiled): 6 minutes 30 seconds. White firm, yolk thick and spreadable but not solid.
Hard-cooked: 12 minutes in the American Egg Board's off-heat method. Both white and yolk fully firm.

The difference between soft and jammy is 30 seconds. The difference between jammy and hard is a full recipe change, off-heat, lid on, longer rest. A medium boiled egg is a jammy egg. The terms are interchangeable; the search term you want is the time.

Altitude Adjustments

At 5000 feet elevation, add 1 minute to all boil times. Water boils at 202°F instead of 212°F, so proteins set slower. At 7500 feet, add 2 minutes (Colorado State University Extension). A large egg at altitude needs 7 minutes 30 seconds for jammy. Do not trust a chart that says +30 seconds per 1000 feet, real adjustment depends on egg size and starting temperature. Test one egg first.

Time	Yolk State	White State
6:00	Completely runny	Set but tender
6:30	Jammy, thick, spreadable	Firm, no wobble
7:00	Set but still moist	Firm, slight rubber if held
7:30	Fully set, crumbly border	Firm, green ring risk

What You Need

A pot large enough for eggs in a single layer. A slotted spoon. A bowl of ice water large enough to hold all eggs. A timer. US large or UK medium eggs, ideally 7-10 days old.

Boiling-Start Method

Bring water to a rolling boil. Lower eggs in gently with a slotted spoon; dropping them from height cracks the shell. Set your timer for 6 minutes 30 seconds. Keep the water at a gentle boil, not a furious roll that bangs eggs against each other. When the timer goes, transfer eggs immediately to the ice water. Leave them for 5 minutes to stop the carryover cooking.

Cold-Start Method

Place eggs in a single layer in the pot. Cover with 1 inch of cold water. Bring to a rolling boil. Cover, remove from heat, and let stand for 1 minute 30 seconds. Then shock in ice water. Serious Eats tests found that cold-start eggs peel more easily than hot-start eggs, but the window is wider and harder to control. Use cold start only if you value peelability over exact doneness.

Batch Boiling

Boiling 6 to 12 eggs at once adds roughly 30 seconds because the water temperature drops more when you add them. Use the same boil time but start timing after the last egg goes in and the water returns to a boil. Test one egg at the end.

A jammy egg is only as good as its surface. Torn white means the marinade soaks into the tear and the yolk leaks. Peeling a soft-centred egg is harder than peeling a hard-cooked egg because the white is less set. Here is the method that works.

Use older eggs. Eggs 7-10 days refrigerated have higher albumen pH (7.6 fresh, 9.2 after a week), which weakens the bond between shell membrane and white. The American Egg Board confirms: older eggs peel more easily than fresh eggs. Buy your eggs a week before you plan to cook them.

Shock in ice water for at least 5 minutes. The thermal contraction pulls the white away from the shell membrane. Serious Eats tests showed this is the single most reliable improvement, more effective than salt or vinegar in the water.

Crack the shell all over. Tap the egg on a hard surface, then roll it gently under your palm to crack the entire surface. Start peeling at the large, air-cell end; that gap gives you a starting edge. Peel under a thin stream of running cold water; the water seeps between shell and white and lifts the membrane.

If the white tears, you waited too long to shock the egg or the egg was too fresh. Do not keep peeling; the soy marinade will flood the tear. Reserve torn eggs for a non-marinated use: chop them into a salad or eat them straight.

Boil Time for Ramen Eggs

Two professional sources give slightly different boil times. Serious Eats uses 6 minutes 30 seconds for a large egg in boiling water, then a 4-24 hour marinade. Just One Cookbook uses 6 minutes 45 seconds. The difference is 15 seconds; both produce a jammy yolk. Use 6:30 if you want a looser center, 6:45 if you want it firmer. Test and adjust for your stove.

The Marinade

A standard ajitsuke tamago marinade is 4 parts soy sauce, 2 parts mirin, 1 part sake (or water), plus sugar to taste. Heat to dissolve the sugar, then cool completely before adding the peeled eggs. Do not marinate hot eggs; the whites tighten and the soy penetrates unevenly.

The Marinade Window

Marinate for at least 4 hours (Serious Eats) or 6 hours (Just One Cookbook) for noticeable flavor. The upper limit is 24 hours. Beyond 24 hours, the salt starts to draw water out of the white, and the texture turns rubbery. The yolk absorbs faster than the white; at 8 hours the yolk center is soy-dark, at 18 hours the whole yolk is mahogany. Beyond 24 hours, the white may develop a cured-meat texture.

If you want uniform color, rotate the container every few hours. If you want a gradient, dark outside, light inside, leave them still.

Unpeeled jammy eggs (shell on) can be refrigerated at 40°F or below and used within 7 days, per USDA FSIS guidance. Peeled jammy eggs, marinated or not, should be eaten within 3 days. The peeled white dries out faster and the surface is exposed to bacteria.

Do not leave hard-cooked eggs at room temperature for more than 2 hours. Do not freeze them, freezing turns the white to sponge and the yolk to grit. If you need to prep ahead, boil and shock the eggs, leave the shells on, and peel only the ones you will marinate or eat that day.

The one thing that most often goes wrong: peeling a fresh egg. You buy eggs on the way home, boil them the same day, and lose half the white. Buy your eggs a week ahead. The difference between a 3-day-old egg and a 10-day-old egg is the difference between a perfect ajitama and a torn disaster.