Why do eggs crack when boiling?
Most cracks come from three things: the egg knocking the bottom of the pot, a fast jump from fridge-cold to a rolling boil, or a hairline crack that was already there.
Common causes
- Dropping them in. An egg dropped into a pot hits the bottom hard.
- A hard rolling boil. Big bubbles knock the eggs into each other and the pot.
- Cold egg, hot water. The air pocket in the wide end expands fast when a cold egg hits boiling water.
- Thin or cracked shells. Check the carton before you buy. USDA says never to buy cracked eggs.
How to stop eggs cracking
- Lower each egg in on a spoon. Don't drop it.
- Turn the heat down to a gentle boil before the eggs go in, then keep it there.
- Cook them in one layer, with room to move.
- If your eggs crack often, try a cold water start, or let them sit out briefly first and take about 1 minute less off the time.
Some people poke a hole in the shell first. The American Egg Board doesn't recommend it: the pin can carry bacteria in, and it can leave hairline cracks.
When one cracks anyway
Keep cooking it. A splash of vinegar in the water helps the leaking white set quickly. USDA says eggs that crack during hard cooking are safe. Eat the cracked ones first.
Soft boiled eggs cracking
Soft boiled eggs have less time to set, so a crack leaks more. Lower them in very gently, and if one cracks, keep it for yourself.
Questions people ask
Is it safe to eat an egg that cracked while boiling?
Yes. USDA says eggs that crack during hard cooking are safe. Eat them first.
Does salt stop eggs cracking?
No. Salt in the water won't stop cracks. Vinegar is more useful, because it helps leaking white set.
Why do my eggs crack even in cold water?
Usually there was already a hairline crack in the shell, or the eggs knocked together once the water boiled hard. Keep the boil gentle.
Should I poke a hole in the egg before boiling?
The American Egg Board advises against it, because the pin can bring in bacteria and cause hairline cracks.