How long to boil corn on the cob

Fresh sweet corn needs 3 to 5 minutes in a rolling boil, not the 20 you will find elsewhere. Pick how you are cooking it: on the grill the timer tells you when to turn it.

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How to boil corn on the cob in three steps

Shuck it and pull off the silk

Pull the husk down from the tip and snap it off at the base, then rub away the silk with your hands. A damp kitchen towel picks up the last few threads. Snap the cob in half if it is too long for the pot.
Into a rolling boil, start the timer

A big pot with enough water to cover the cobs, at a full rolling boil before the corn goes in. Start the timer when the water comes back to the boil. In a big pot that takes under a minute, and the times on this page count from there.
Out when it rings, straight to the table

Lift the cobs out with tongs as soon as it rings. Left in the hot water they keep cooking, and the kernels go from sweet and crisp to starchy. Butter and salt them while they are still steaming.

Corn on the cob cooking times, by method

For medium ears of sweet corn, about 20 cm long. Boiling times count from when the water returns to the boil, microwave times assume about 1000 W, and each ear takes the same time on the grill however many are on it.

Not yet Pale and dull. Another minute or two.
Just right Bright, glossy and plump. Take it out now.
Overcooked Darker, dented and dull. Sweet corn gone starchy.

Cooking time, heat and turning for corn on the cob by method
Method	Time	Heat	Turn
Boiled, fresh sweet corn	3–5 min	Rolling boil	–
Boiled, from the shop	5–7 min	Rolling boil	–
Boiled in the husk	10–12 min	Rolling boil	–
Boiled from frozen	6–8 min	Rolling boil	–
Steamed	6–8 min	Lid on	–
Microwave, 1 ear in husk	3–4 min	High	+2 min rest
Microwave, 2 ears	6–7 min	High	Halfway
Microwave, 4 ears	10–12 min	High	Halfway
Oven, in foil	25–30 min	200 °C · 400 °F	–
Oven, no foil	30–35 min	180 °C · 350 °F	Halfway
Grill, husked	10–15 min	Medium-high	Every 3 min
Grill, in the husk	15–20 min	Medium	Every 5 min
Grill, in foil	15–20 min	Medium-high	Every 5 min
Air fryer	10–12 min	200 °C · 400 °F	Halfway
Air fryer, from frozen	14–16 min	200 °C · 400 °F	Halfway
Blanch before freezing	7–11 min	Rolling boil	Ice bath

The biggest difference is not the method but the corn. Sweet corn starts turning its sugar into starch the moment it is picked, so a cob from the field that morning is sweet and tender after three minutes, and one that has been in a supermarket for a week needs closer to seven. Older recipes that say 15 or 20 minutes were written for field corn and old varieties, and they turn modern sweet corn tough.

In a microwave under 1000 W, add about a third to the time. Leave the husk on: it holds the steam in, and the cob slides out clean once the rest is over and the husk is cool enough to handle.

Food safety

What the official guidance says

Frozen sweetcorn: Frozen vegetables such as sweetcorn can carry bacteria and should be cooked before eating, not eaten straight from frozen.
Source: UK Food Standards Agency
Freezing corn on the cob: Blanch in boiling water first: 7 minutes for small ears, 9 for medium and 11 for large, then cool promptly and completely.
Source: National Center for Home Food Preservation

Checked against the official pages, September 2026.

Why the answers disagree

Search for how long to boil corn and you will find anything from three minutes to twenty. Both ends are right for some corn. Freshly picked sweet corn barely needs heating through, while old, starchy or field corn needs much longer to soften.

For the sweet corn sold in shops today, the answer is short. It is already edible raw, so the pot only has to heat it through and set the colour. Everything past that makes it worse, not safer.

Salt, sugar and milk

Salting the water does very little. In five minutes the kernels take up almost none of it, so season at the table, where you can taste it.

Some cooks add sugar or a splash of milk to the pot to sweeten older corn. It helps a tired supermarket cob a little. Fresh sweet corn does not need it, and a shorter boil does more for any corn than anything added to the water.

Keeping it warm, and freezing it

If dinner is not ready, turn off the heat and leave the cobs in the hot water with the lid on. They keep for about ten minutes without going soft. Much longer and they overcook.

To freeze corn on the cob, blanch it first. The National Center for Home Food Preservation gives 7 minutes for small ears, 9 for medium and 11 for large, then straight into iced water until cold all the way through, so it does not taste of the cob.

Popular timers

Questions about cooking corn on the cob

How long do you boil corn on the cob?

3 to 5 minutes for fresh sweet corn, and 5 to 7 for corn that has been in the shop for a few days, counted from when the water comes back to a rolling boil. Frozen cobs take 6 to 8 minutes. Take them out as soon as the kernels are bright yellow and glossy. Boiling longer makes them tough and starchy, not more tender.

How long do you cook corn on the cob in the microwave?

3 to 4 minutes on high for one ear, left in its husk, then 2 minutes of rest before you peel it. Two ears take 6 to 7 minutes and four take 10 to 12, turned over halfway. The husk traps the steam, so there is no need for water or cling film.

How long do you cook corn on the cob in the oven?

25 to 30 minutes at 200 °C (400 °F) wrapped in foil with a little butter, or 30 to 35 minutes at 180 °C (350 °F) straight on the rack, turned halfway. Foil keeps it juicy. Bare on the rack it browns a little and tastes nuttier.

How long do you grill corn on the cob?

10 to 15 minutes over medium-high heat for husked corn, turning a quarter every 2 to 3 minutes so every side chars a little. In the husk or in foil it takes 15 to 20 minutes, turned every 5. The grill timer above rings at every quarter turn.

How long do you boil frozen corn on the cob?

6 to 8 minutes in a rolling boil, straight from the freezer. Do not thaw it first. Frozen cobs have been blanched already, so they need heating through rather than cooking from raw, but they do need it: the UK Food Standards Agency advises that frozen vegetables such as sweetcorn are cooked before eating.

How can you tell when corn on the cob is done?

The kernels turn a deeper, brighter yellow, go glossy and look plump and tight against each other. Press one with a fingernail: done corn bursts with sweet, milky juice. Pale, dull kernels need another minute. Dented, darker, wrinkled ones have gone too far.

Do you put corn in boiling or cold water?

Boiling. Corn started in cold water sits in warm water while the pot heats, and that is when it turns starchy. Bring a big pot to a full rolling boil first, add the cobs, and start the timer once it is bubbling again.

Can you overcook corn on the cob?

Yes, and it is the most common mistake. Past about 10 minutes in boiling water, sweet corn loses its crispness, the kernels wrinkle and the sugar tastes flat. If you are not sure, take it out early. It keeps cooking for a minute on the plate.

How do you freeze corn on the cob?

Husk it, blanch it in boiling water for 7 minutes for small ears, 9 for medium and 11 for large, then cool it in iced water for about as long. Drain, dry and freeze in bags. Those are the times from the National Center for Home Food Preservation. To cook it later, boil it from frozen for 6 to 8 minutes.