How Long to Boil Shrimp: Raw, Frozen Cooked and King Prawns

Start timing when the water comes back to the boil after the shrimp go in. Salt the water and keep the heat at medium so the boil does not stop. The numbers are a guide; the flesh tells you more precisely: it turns from grey and translucent to white and opaque.

You can drop shrimp into the boiling water straight from the freezer: the water cools more and takes longer to come back to the boil, and the shrimp need a little more time after that. In this case go by the colour of the flesh rather than the timer.

"King prawns" in shops are usually whiteleg shrimp (vannamei): "king" is a trade name, not a separate species. Tiger prawns are usually larger, so they take longer. Squid needs a different approach, see how long to boil squid.

The pack is the most reliable guide. Frozen shrimp are sold raw, blanched or cooked, and the label says which. The Eurasian standard GOST 20845-2022, for example, requires each type to carry its own note:

• Cooked frozen. Fully cooked before freezing. The label says the product is ready to eat after thawing.
• Blanched. Only the surface has been set by boiling water or steam. The label says they must be heated for 1.5-2 minutes.
• Raw frozen. Raw shrimp that must be cooked through.

Colour helps too, with caveats. Raw shrimp are grey, bluish-grey or translucent; cooked ones are pink or pink-orange with firm white flesh. But Argentine red shrimp are red even when raw, and the same standard allows the red dye Ponceau 4R (E124) in cooked frozen shrimp, so the label has the final word.

A dark head on a raw shrimp is not always a sign of spoilage: greenish or light-brown heads are allowed, and the dark blue top of the head on raw shrimp disappears during cooking. Watch for other signs instead: an ammonia smell, a sour smell or sticky slime. Such shrimp should not be cooked or eaten.

• In the fridge. The gentlest way: put the shrimp in a covered bowl and leave them overnight, 6-12 hours. This is what the US Food and Drug Administration (FDA) recommends.
• In cold water. The quick way: seal the shrimp in a bag, put it in cold water and change the water every 30 minutes. A 0.5 kg bag thaws in about an hour; cook the shrimp straight away.
• In the microwave. On the defrost setting, only if you are cooking them immediately.
• From frozen. Raw and cooked frozen shrimp can go straight into boiling water, a sauce, soup or pasta; the time only increases slightly.

Do not leave shrimp to thaw on the counter at room temperature: the US Department of Agriculture (USDA) advises against it because the surface warms up before the centre thaws. Use shrimp thawed in the fridge within a day.

1. Thaw the shrimp, or just rinse them in a colander under cold water to wash off the ice glaze.
2. Bring plenty of water to the boil, about 2 litres per 1 kg of shrimp: a large pot comes back to the boil faster. Salt it: 1 tbsp of salt per litre for peeled shrimp, 1.5 tbsp for shell-on shrimp.
3. For flavour, add a bay leaf, a few allspice berries, a sprig of dill or a slice of lemon.
4. Drop the shrimp into the boiling water and wait for it to boil again. Start timing from that moment, using the table.
5. Check one shrimp: the flesh should be white and opaque all the way through. A shrimp curled into a tight ring is already overcooked.
6. Lift the shrimp out straight away with a slotted spoon. For a salad or a cold starter, plunge them into a bowl of iced water for 1-2 minutes, then pat dry.

Iced water stops the cooking so the shrimp do not turn rubbery. Use clean ice and a clean bowl that have not touched raw seafood: in Spain in 2012 about 100 people fell ill from shrimp that had been cooled after boiling in ice that had likely been in contact with raw shellfish.

Frozen cooked shrimp were cooked before freezing, so they do not need boiling again. Once thawed in the fridge they can be eaten cold or added to salads and starters. To serve them hot and fragrant, drop them into boiling salted water with spices for 1-2 minutes after it returns to the boil, large king prawns for 2-3 minutes. Add cooked shrimp to pasta, soup or rice at the very end, just to heat through.

A step-by-step recipe with photos: how to cook frozen cooked king prawns.

Every extra minute in boiling water makes shrimp drier and tougher. In experiments with shrimp boiled in brine, the longer the cooking and the saltier the water, the more moisture and protein the shrimp lost and the tougher the flesh became.

For pregnant women, the NHS advises eating cold ready-cooked prawns only after heating them until steaming hot, and avoiding raw shrimp and other raw shellfish altogether.

• The flesh is white or tinged with pink, opaque and pearly all the way through. This is how the FDA describes cooked seafood.
• 63 °C (145 °F) in the thickest part, if you have a thermometer. Test kitchens take shrimp off a little earlier, at 60 °C (140 °F), because the temperature keeps rising slightly while they are lifted out and cooled.
• The shrimp is curled into a loose "C". A tight "O" means it has been overcooked.
• Floating is not a reliable sign of doneness: there is no evidence for it, so check the flesh.

• For salads. Boil the shrimp according to the table, cool them in iced water, pat dry and peel. Frozen cooked shrimp only need thawing in the fridge. Peeled medium shrimp are the most convenient: there is no need to cut them.
• As a snack. Boil water with peppercorns, bay leaves, dill and garlic, simmer the spices for 10 minutes, then add salt and cook shell-on shrimp according to the table. Shell-on shrimp are easy to peel right at the table.
• Off the heat. For large peeled shrimp there is a gentle method from America's Test Kitchen: bring the water and spices to the boil, take the pot off the heat, add the shrimp, cover for 8-10 minutes, then move them to iced water. The flesh heats gently and does not turn rubbery.
• In hot dishes. Add shrimp to pasta and sauces at the end: tagliolini with shrimp, pasta with shrimp in cream sauce, shrimp and pineapple pizza.

• Boiling frozen cooked shrimp for 5-10 minutes. They are already cooked; long boiling only dries them out. 1-2 minutes is enough.
• Crowding a small pot. The water stops boiling for a long time, and the shrimp overcook while you wait for it to boil again. Use about 2 litres of water per 1 kg or cook in batches.
• Leaving shrimp in the hot liquid. Residual heat keeps cooking them. Lift them out right away and, for salads, cool them in iced water.
• Thawing in warm water or on the counter. The surface warms up before the centre thaws. Thaw shrimp in the fridge or in cold water in a sealed bag.
• Judging doneness by the shell colour alone. Argentine red shrimp are red even when raw, so check the flesh: it should turn white and opaque.

There is also a cold-start method: the shrimp go into cold water that is heated to 71 °C (160 °F), and the flesh reaches 60 °C (140 °F) in about 12 minutes and stays juicy. Cook's Illustrated uses it for shrimp cocktail, but for everyday boiling the table above is simpler.

The dark line along the back is the shrimp's gut. It is tasteless and harmless, and removing it is purely cosmetic. On large shrimp the vein is more visible, so it is usually taken out; on small ones it is left in.

Shrimp can be boiled shell-on or peeled. Shell-on is handy for snacks and serving whole, peeled is easier for salads and pasta. To peel a shrimp, twist off the head and remove the shell in rings from head to tail; the tail can stay on. Lift the vein out with a toothpick, or make a shallow cut along the back and pull it out.

• Glaze. Frozen shrimp are coated in a protective layer of ice. In the Eurasian Economic Union it may not exceed 7% of the weight for peeled and headless shrimp and 14% for whole ones, and the label states the net weight without the glaze.
• Size. Numbers like 16/20 or 26/30 on US and imported packs give the count per pound: the smaller the numbers, the larger the shrimp. America's Test Kitchen calls 16/20 jumbo, 21/25 extra-large, 26/30 large, 41/45 medium and 51/60 small. Multiply by 2.2 to get the count per kilogram: 16/20 per pound is 35-44 per kg.
• Ingredients. Phosphates (E450, E451) are allowed in cooked frozen shrimp to hold water. According to the USDA, 100 g of cooked shrimp with such additives contains 947 mg of sodium, compared with 111 mg without them. Choose packs with a short ingredient list.
• Inside the bag. The shrimp should be separate, without snow or a stuck-together block of ice: those are signs of thawing during storage.

The tip that "a straight tail means the shrimp were refrozen" is widely repeated but has no evidence behind it. The packaging, the use-by date and the ingredient list tell you more.

Refrigerate cooked shrimp within 2 hours, or within 1 hour in hot weather. Keep them in a closed container at 4 °C (40 °F) or below for 1-2 days: the UK Food Standards Agency (FSA) advises eating leftovers within 48 hours, the FDA allows 3-4 days. Raw chilled shrimp keep for 1-2 days.

In the freezer, cooked shrimp keep their quality for 4-6 months. Raw shrimp thawed in the fridge can be refrozen, although they become drier; shrimp thawed in water or in the microwave should be cooked first. Many packs say "do not refreeze", so follow the label.

100 g of cooked shrimp has 99 kcal, 24 g of protein, 0.3 g of fat and almost no carbohydrates; raw shrimp has 85 kcal and 20 g of protein (USDA data). Cooked shrimp contain 189 mg of cholesterol per 100 g.

Crustacean shellfish are among the major food allergens, and reactions can be severe. The main shrimp allergen, the protein tropomyosin, survives cooking, so cooking does not make shrimp safe for people with the allergy. Raw and undercooked shrimp can carry Vibrio bacteria: proper cooking kills them, while chilling and freezing do not.