What shrimp count sizes actually mean

The words on the front of the bag are unregulated. One brand's jumbo is another brand's large, and neither term has a legal definition in the United States.

The numbers are the real information, and once you understand them you can buy accurately anywhere.

The count is shrimp per pound

16/20 means sixteen to twenty shrimp make up one pound. So a two-pound bag contains between thirty-two and forty shrimp.

Smaller number, bigger shrimp. This is the part that catches people out, because it runs the opposite way to almost every other sizing system.

U/12 means under twelve per pound. The U stands for under, and it is used when the shrimp are large enough that the count no longer needs a range. U/10, U/12 and U/15 are all very large shrimp.

The common sizes, and what they are for

• U/10 to U/15, sold as colossal or extra colossal. Impressive, expensive, and genuinely difficult to cook evenly. Three per person is generous. Best grilled or served as a plated first course rather than heaped on a tray.
• 16/20, sold as jumbo. The cocktail size. Large enough to read as a special occasion, small enough that four or five per person is a sensible serving and the tray does not look sparse.
• 21/25, sold as extra large. Perfectly good and often better value. Six or seven per person. The tray is a little less dramatic.
• 26/30 and 31/40, sold as large or medium. For salads, pasta, scampi and skewers. Too small for a cocktail platter, where they get lost in the ice.
• 41/50 and smaller, sold as small or salad. Fine in a shrimp salad. Not for presentation.

Why 16/20 is the cocktail size

Three practical reasons.

It cooks evenly. At 16/20, a two-minute poach brings the centre up to temperature at roughly the same moment as the surface. Colossal shrimp have enough mass that the outside is done before the middle, which is why they suit dry heat better.

The serving arithmetic works. Four to five per person is a portion that feels right and lets a pound stretch across four guests.

It sits properly on ice. Large enough that a single layer covers a tray without looking thin, small enough that guests take one cleanly instead of disturbing the whole arrangement.

Shell-on, peeled, and what you are actually buying

Counts are given for raw, shell-on shrimp. If you buy peeled, you get more shrimp per pound because the shells are gone, so the effective size is smaller than the count suggests.

Peeling loses roughly fifteen percent of the weight. Three pounds shell-on gives you about two and a half pounds of edible shrimp.

Buy shell-on if you can. It costs less per pound of shrimp, it thaws with better texture, and peeling takes about ten minutes for three pounds.

Check the ingredient list for sodium tripolyphosphate, usually listed as STPP or as sodium phosphate. It makes shrimp hold water so they weigh more, and it gives cooked shrimp a slightly soapy, slippery quality. Shrimp with nothing on the ingredient list but shrimp and salt are worth the small premium.

Fresh versus frozen

Almost all shrimp sold at an American fish counter as fresh were frozen at sea and thawed by the store. You are buying the same product, with less control over how long ago it thawed.

Buy frozen. Thaw it yourself overnight in the refrigerator, and you know exactly what you have.

Common questions

What does 16/20 mean on a bag of shrimp?

Sixteen to twenty shrimp make up one pound. The count is always given for raw shell-on shrimp, so a two-pound bag holds between thirty-two and forty.

Is jumbo bigger than colossal?

No. Colossal is larger, but neither term is legally defined in the United States. Use the count numbers instead: colossal is typically U/15 or larger, jumbo is around 16/20.

What size shrimp is best for shrimp cocktail?

16/20 count. It cooks evenly in a two-minute poach, four to five per person is a sensible serving, and it fills a tray in a single layer without looking sparse.