Shrimp Size 16/20 and 21/25: How Many Pieces per Kilo?

A 16/20 shrimp size means 35 to 44 pieces per kilo when the count is per pound (453.6 g). It means 16 to 20 pieces per kilo when the plant counts in metric. The 21/25 follows the same rule: 46 to 55 pieces per kilo when counted per pound, 21 to 25 when counted per kilo. The label is the same, but the two readings are a factor of 2.2 apart.

I went back through the pages that currently rank for this query. One of them uses both units on the same page without telling the reader. This guide gives the exact conversion, shows what it changes on the plate and in an order, and then lists the lines to write into the contract.

Shrimp size: per pound or per kilo, who counts what?

A shrimp's size grade is the number of pieces it takes to make one unit of net drained weight. That unit is a pound (453.6 g) under the US convention and a kilo in metric. The smaller the first number in the range, the bigger the shrimp. A "16/20" label never states its own unit.

According to the restaurant L'Accostage (restaurant-laccostage-ouistreham.fr), the commercial scale runs from 8/12 down to 150/200 for very small shrimp. Everything between those two ends depends on which unit is assumed.

Why do two conventions exist side by side?

Two-number grades such as 16/20, 21/25 and 31/40 come from export pricing, where shrimp are counted per pound. French retail thinks in kilos. Christophe, a fishmonger with the Chezmonpoissonnier chain, explains that a "50" label means 50 to 70 shrimp per kilo, or 5 to 7 per 100 g. Both practices are legitimate, but they don't mix.

The tirsportifchabris.fr blog shows the trap. It defines the 30/50 size as 30 to 50 shrimp per pound, then explains that 20/30 means 20 to 30 shrimp in a kilo. The a-la-fine-maree.fr guide states its unit from the outset (16/20 per pound, i.e. 35 to 44 pieces per kilo), rounding the pound to 450 g. A size grade with no unit isn't a specification, it's a dispute waiting to happen.

At EMG Seafood, an exporter based in Vietnam, most of the disputes that come up when a container arrives stem from a size discrepancy that was never written into the contract. My Search Console data, pulled on 9 November 2026, shows "calibre crevette" (shrimp size) at an average position of 10.5 with 77 impressions. People are asking the question, and the top-ranking answers contradict each other on the unit.

How many pieces per kilo in 16/20 and 21/25?

A 16/20 per pound gives 35 to 44 pieces per net kilo, or 22.7 to 28.3 g per piece. A 21/25 per pound gives 46 to 55 pieces, or 18.1 to 21.6 g each. Read directly per kilo, the same numbers mean 16 to 20 pieces (50 to 62.5 g) and 21 to 25 pieces (40 to 47.6 g).

The size guide on emg-seafood.fr works per kilo, which is why it gives 50 to 62 g for a 16/20 and 25 to 32 g for a 31/40. The full chart from U10 to 80/100 is in Shrimp size: size chart from U10 to 80/100. The table above sets the two readings side by side so the gap jumps out at a glance.

How do you convert a per-pound size into pieces per kilo?

Multiply each end of the range by 2.2046, the number of pounds in a kilo. For 16/20: 16 × 2.2046 = 35.3 and 20 × 2.2046 = 44.1, so 35 to 44 pieces. For 21/25: 21 × 2.2046 = 46.3 and 25 × 2.2046 = 55.1, so 46 to 55.

To get the weight of one piece, divide 453.6 g by the number of pieces per pound, or 1,000 g by the number of pieces per kilo. The ranges sit back to back: a 16/20 stops at 44 pieces per kilo and a 21/25 starts at 46. The fishmonger's shortcut also works for estimating a portion: 100 g of a 50/70-per-kilo size gives you 5 to 7 shrimp.

The same 16/20 label can mean a 25 g shrimp or a 55 g shrimp. The unit is what defines the size.

What remains is to see what this conversion changes in the kitchen, then in an order. The impact of the 2.2 factor on a quote is covered in Shrimp size: the 2.2 factor that skews your quotes.

What 16/20 or 21/25 changes on the plate and in the order

Going from a 16/20 to a 21/25 per pound, the piece drops from about 25 g to about 20 g at mid-range, which is 22% lighter. For a 150 g net portion, that means 6 pieces of 16/20 versus 8 of 21/25. So the size grade determines what the diner sees on the plate, not the weight they pay for.

Which size for which foodservice use?

The emg-seafood.fr size guide pairs 16/20 with HORECA grilling and points institutional catering towards much smaller sizes, from 41/50 according to that guide. A 16/20 makes sense when the whole piece is on show (skewers, plancha, whole shrimp on the plate). A 21/25 works when the shrimp are mixed into a dish (stir-fry, risotto, salad) and consistency matters more than size.

If the dish uses only the meat, yield after peeling is around 50%. For 300 g of meat, allow 600 g of whole shrimp plus a 10 to 15% margin, according to tirsportifchabris.fr. This choice mostly matters to buyers signing for a container. A single restaurant buys from its wholesaler: it reads the size grades but doesn't write them into a contract.

Why doesn't the size grade alone give you the cost per portion?

Cost per portion is the price per net kilo multiplied by the portion weight, after glazing and yield. Size only comes into it through the price per kilo, which rises with size. According to EMG Seafood's Q2 2026 data, farmed Vannamei U10 (Penaeus vannamei, the most widely farmed shrimp species in the world according to the FAO) is invoiced at €14.50 to €17.00/kg net, DDP Antwerp.

The full calculations, glazing included, are in Shrimp portion cost in foodservice: calculating by size, glazing and yield. Glazing on its own can distort the net weight: see Shrimp glazing rate: how to avoid paying shrimp prices for water.

What to write in your specification for a 16/20 or 21/25 size

A size specification fits in four lines: the counting unit, the range in pieces per kilo net drained weight, the out-of-size tolerance and the inspection method. These are the lines we have the plant sign before any order. They supplement the definition of frozen product given in the Codex Stan 92-1981 standard (FAO/WHO), since size remains a contractual decision.

• Unit: "size expressed in pieces per kilogram net drained weight, glaze deducted".
• Range: "16/20 per pound (453.6 g), i.e. 35 to 44 pieces per kilogram net drained weight".
• Tolerance: a maximum percentage of out-of-range pieces and broken pieces (broken count), negotiated before the order, never after.
• Inspection: a count on a sample taken at receipt, after thawing and removing the glaze.

Here is what that changes in an order. On a 10-tonne net lot, a 16/20 per pound comes to roughly 353,000 to 441,000 pieces. Read per kilo, the same label would mean 160,000 to 200,000, each shrimp twice as heavy. A buyer who expects 50 to 62 g pieces and receives 25 g ones is paying for a size they don't get.

To see these lines with figures, request an FOB quote by size within 48 hours. It is priced FOB Ho Chi Minh City, for a minimum of one 20' FCL container (mixed references possible), with the unit spelled out for each size.

How do you check the size on receipt?

Thaw a sample, remove the glaze, weigh the net drained weight, then count the pieces and compare against the contractual range. A difference of a few pieces per kilo is within tolerance. A difference of a whole size grade is not. The step-by-step method is in Shrimp size: how to prove what you paid for.

If the tolerance isn't written down before the container ships, it gets negotiated afterwards, and not in your favour.

Which size to list: the verdict on 16/20 and 21/25

For shrimp size, a 16/20 equals 35 to 44 pieces per kilo and a 21/25 equals 46 to 55, provided the contract is talking in pounds. Per kilo, they are 16 to 20 and 21 to 25 pieces. Worth listing: both grades, with the unit written out and the tolerance quantified. To avoid: any size quoted without a unit.

Should you order 16/20 or 21/25?

I list 16/20 per pound for dishes where the piece is on show, and 21/25 per pound for mixed preparations, where the 22% difference in piece weight goes unnoticed. I would never sign a purchase order whose size line states neither a unit nor a tolerance, whatever the price per kilo.

In our dealings with plants, two-number grades are most often read per pound. That's the reading I assume by default, but I have it confirmed in writing on every order. For the size line that removes the ambiguity, see also Shrimp size: 16/20 doesn't mean 16 to 20 per kilo.