For a large egg lowered into already-boiling water, straight from the fridge: 5 minutes for a liquid dippy yolk, 6 minutes for soft with a runny yolk, 6:45 for jammy, 8 minutes for medium, and 11 minutes for hard boiled. Egg size shifts every one of those by about 30 seconds per step.

The moment the eggs go into water that is already at a rolling boil. If you are starting the eggs in cold water instead, start the timer when the water reaches a full rolling boil — and switch the timer to cold-water start, because the egg has already been heating on the way up and needs less time from the boil, not more.

No, and this is the single most common mistake. More eggs cool the water down, so it takes longer to come back to a boil — but once it is boiling again, a dozen eggs cook in the same time as one. Use a bigger pot, wait for the boil to return, then start the timer.

A hot egg keeps cooking after it leaves the water. Without an ice bath, a 6:45 jammy egg is closer to a medium egg by the time you peel it. Cold water stops the cooking on the spot, prevents the grey-green ring on hard boiled eggs, and makes the shells come away far more cleanly.

USDA guidance is up to one week refrigerated, whether they are still in the shell or already peeled. Get them into the fridge within two hours of cooking. Peeled eggs dry out, so keep them in a sealed container.

Yes, by about 30 seconds per size step, which is the difference between runny and set at the soft end. Small runs a minute under large, medium 30 seconds under, extra large 30 seconds over, jumbo a full minute over. Not sure? Large is the safe assumption in the US and the UK.