What's the right way to hard boil eggs?

I find I always have trouble scaling the amount of time the eggs should be boiled, cooled, etc. for different-sized batches of hard-boiled eggs.

I've heard a variety of "folk lore"-type rules for how it should be done, but what's really the right way?

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If you've got a sous vide setup you can set it for about 166ºF-ish for an hour and ensure they're cooked to perfection. However, you need to make sure that you've got it exactly that temperature as if you're too low the egg will come out runny. It's still safe, and arguably tastes better, but it's not hard boiled. In fact, this method doesn't boil the eggs at all, so I guess they're "hard cooked".

For a visual representation how minute changes in temperature changes the compositions of an egg see Figure 4.1 of Douglas Baldwin's "A Practical Guide to Sous Vide Cooking".

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There is a whole science on that. Simply saying:

source: blog.khymos.org

Where:
t - time
T - temperature
M - mass in grams

While this is for soft-boiling eggs, I believe you can easily adjust it for hard-boiling.

Even an application, that cosiders all the variables, exists:

Kunsten å koke et egg - Google translated

While for me this is far more complicated, if you're interested you can read all the details in the post "Towards the perfect soft boiled egg".

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This is fabulous and hilarious! – Gabriel Hurley Jul 13 '10 at 18:59
I'm sorry, but this answer is virtually useless. There is no practical way to determine the temperature of the egg or yolk when boiling. Funny, but not a useful answer. – Daniel Bingham Jul 26 '10 at 15:14
Daniel, if you look up what temperature you want the yolk and egg to be (based on how done you want them), you can work out the time to get there. – s_hewitt Sep 8 '10 at 3:14
That equation is missing height above sea level (effects the temperature in which water boils). – Techboy Nov 27 '11 at 22:44
The equation includes the temperature of the water, so it does take into account height above sea level. – Frank Szczerba Jan 10 '12 at 16:25

I don't boil eggs enough to keep a feel for the timing... So a few years back, I picked up a handful of these.

They're sold under a few different names, but the idea is the same: sturdy plastic that changes color as it heats. Drop it in with the eggs, and pull & chill them all when the color band hits the spot you're looking for.

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Those look really cool! Do you keep it at the same temperature as your eggs? – Peter V Jul 20 '10 at 19:37
@Peter: I usually just let the eggs sit out a bit before cooking them. – Shog9 Jul 20 '10 at 19:38

I've never adjusted the length of time based on number of eggs. As long as the water is boiling I don't think it would take any longer to cook a dozen than to cook one (it might take the water longer to come up to boiling, I guess).

For hard boiled I normally bring them up to the boil and then turn the heat off, and leave them for 15 minutes. If you like them less well-cooked, you could reduce this to 12 minutes. Then empty the pan and re-fill it cold water a couple of times to cool them down quickly. Leave rest of them sitting in the cold water while you prepare each one.

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Totally agree. The hot-soak concept also makes it hard to overcook them. – Andres Jaan Tack Jul 13 '10 at 17:28
What about eggs right from the fridge vs. eggs that are at room temperature? Does the age of the eggs make any difference in the actual boiling? I hear it does affect how they peel. – John Dyer Jul 17 '10 at 1:46
Don't know about eggs from the fridge - round here (UK) we tend to keep them in the cupboard. The only difference the age makes is that they are more likely to crack during boiling. – Vicky Jul 18 '10 at 20:22
I've switched to this technique. I've found that it produces eggs that are perfectly boiled and never have that dark layer between the yolk and white -- that's an indicator that they were overcooked. ALSO: it's important to remove them from heat when you turn the heat off. You want them to get to a boil briefly and not stay there for any length of time. – jcollum Aug 4 '10 at 20:28
Wikipedia seems to think that age does affect "peel-ability" The fresher the hard boiled egg, the easier it peels. en.wikipedia.org/wiki/Boiled_egg#Peeling – BZink Jan 10 '12 at 2:40

I'm not sure there is a definitive way to cook hard boiled eggs, but the guidelines I tend to follow are:

• Don't cook eggs straight from the fridge, let them adjust to room temperature.
• Don't use fast boiling water, a gentle roll is enough
• For soft boiled eggs, place them in boiling water (enough to cover the egg by about 2cm) for one minute. Remove from the heat and cover. Leave them for approximately 6 minutes.
• For hard boiled eggs place them in boiling water and simmer for about 6 minutes. Once done cool them as quickly as possible, by running them under cold water.

Timings may have to be adjusted slightly, depending upon the freshness of the eggs and also personal preference.

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