How to use the online timer
Nine minutes gives a yolk that is fully set but still bright yellow and slightly moist at the centre — firm enough to slice, grate or mash, and nothing like the chalky, faintly grey version that comes out of a pan left to its own devices. That difference is worth caring about for anything the egg is going into: salads, sandwiches for a packed lunch, or a plate of mezze.
Count from the moment the eggs meet boiling water, then move them straight into cold water the second the time is up. That immediate cooling is what prevents the greenish ring around the yolk, which is a reaction between iron and sulphur that keeps developing as long as the egg stays hot. The count runs in this page, so keep the tab open until it sounds.
Hard-boiled eggs keep for about a week in the fridge, but only in their shells — peeled ones dry out and pick up whatever else is in there within a day. If they are going in a lunchbox in summer, keep them cold until they leave the house, since an egg that has spent three hours in a warm car is not worth the risk.
Common questions
What causes the grey-green ring around the yolk?
A reaction between iron and sulphur that develops the longer the egg stays hot. It is harmless, and moving the eggs straight into cold water the moment the time is up prevents it almost entirely.
How long do they keep once cooked?
About a week in the fridge in their shells. Peeled, they dry out and take on other flavours within a day, so leave the shells on until they are needed and keep them cold if they are going out of the house.
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