Shrimp size counts: 16/20 doesn't mean 16 to 20 per kilo

A shrimp size count is the number of pieces in a given unit of weight, and that unit varies from one supplier to the next. A 16/20 sold per pound (453.6 g) means 35 to 44 shrimp per kilo, not 16 to 20. That one unit mix-up is enough to skew a quote comparison by 20% or more. I see buyers make the same mistake again and again: they compare prices per kilo without first checking that the counts, product forms and reference weights actually match.

This article starts with how to read a count (what it measures, how to convert it), then shows what that means for a real order: cost per piece, the tolerance to ask for, and the exact lines to write. It's aimed at whoever drafts the specification for a container, not at someone standing at the supermarket counter.

What a shrimp size count actually measures

A shrimp size count is a range of pieces per unit of weight: the smaller the number, the bigger the shrimp. According to a-la-fine-maree.fr, a 16/20 count means 16 to 20 shrimp in 450 g, or 35 to 44 per kilo. The same logic holds for every size.

Why does the number run backwards?

A count is a number of pieces, not a size. The videos on the Demander Et Répondre channel keep coming back to the same rule: an 8/12 gives you huge shrimp, a 60/80 tiny ones, "it's the opposite of clothing sizes". The rule is right, and that channel explains it more clearly than anyone else.

But those videos stop there, because they're made for consumers. A container buyer has to go further: which unit, which weight, and what tolerance.

Pound or kilo: how do you convert without getting it wrong?

Multiply the count by 2.2046 to go from per pound to per kilo. So a 31/40 per pound becomes 68 to 88 pieces per kilo, and a 21/25 becomes 46 to 55. In offers from Vietnamese processing plants, peeled tails (PDTO) are usually quoted per pound, while whole shrimp (HOSO) are more often quoted in pieces per kilo. Check every quote line, because both conventions can sit side by side in the same quote.

The table below gives the conversion for the counts we're most often asked for on Vannamei PDTO.

For the full grid from U10 to 80/100, see the shrimp size count table, and for the inverted-number trap from a buyer's point of view, the backwards count that catches buyers out.

The count depends on the product form

The same count doesn't describe the same animal depending on whether the shrimp is whole, headless or peeled. The Demander Et Répondre channel puts it simply: the count applies to the product as sold, so a peeled tail is physically smaller than a whole shrimp of the same count, because the head has been removed.

How do you compare HOSO, HLSO and PDTO at the same count?

You don't compare them, you convert. A 30 g HOSO shrimp (head-on shell-on, whole with the head) corresponds to a much lighter PDTO tail (peeled deveined tail-on). Sources disagree on how much weight is lost. The video "How to choose your shrimp size" says you lose half the weight once peeled, while a-la-fine-maree.fr puts the shell alone at 30 to 40% of total weight.

The two figures don't contradict each other, they measure different things: on a HOSO shrimp, the head comes on top of the shell. I never put a flat yield figure in a specification. I require the yield measured by the plant on the actual lot.

Which count should you pick for which use?

The cooking tips in the videos have a purchasing equivalent. For the griddle or the grill, the channel recommends large sizes (16/20 and up) because small ones dry out. For a salad or a risotto, it sees 40/60 per kilo as the right compromise. A buyer at a purchasing group turns this into two questions: which piece still looks good on the final plate, and at what cost per piece.

The second question is the one that matters, because you can put a number on it. As an illustration, a 31/40 at €9.00 per net kilo works out at about €0.115 per piece, based on an average of 78 pieces per kilo. A 16/20 at €12.00 per net kilo, at 40 pieces per kilo, comes to €0.30 per piece. The foodservice breakdown is in portion cost by size count.

Glazing and tolerance: what the count doesn't stop you paying for

Glazing is the layer of ice applied to frozen shrimp to protect it from dehydration, and you pay for it at the shrimp price unless the contract caps it. The video "What size are large shrimp?" warns that this layer can make up as much as 30% of total weight. The count itself is taken on deglazed shrimp: glazing doesn't change it, but it does change the gross price per kilo.

Why is net deglazed weight the only reliable basis?

Without a net deglazed weight, two offers at the same price per kilo aren't worth the same. Take €8.00 per gross kilo with 20% glazing: a kilo of actual shrimp costs you €10.00. An offer at €9.00 with 10% glazing also comes to €10.00, even though it looks more expensive. The only price that counts is the price per net deglazed kilo.

The topic is covered in detail in the glazing rate to cap so you don't pay for water.

What count tolerance should you ask the plant for?

A count range describes an average over a sample, not a piece-by-piece guarantee. In a 31/40 lot, a few pieces outside the range are normal. The real risk is a lot whose average drifts towards the bottom of the range, which means smaller shrimp at the same price. That's why you need to set the counting method, the sample size and the maximum allowed deviation, rather than settling for "31/40" on the proforma invoice.

The Codex Alimentarius, published by the FAO and the WHO, includes standard Codex Stan 92-1981 on quick-frozen shrimps and prawns. It's a useful reference point, but it doesn't replace a count line with actual numbers in your contract. If there's a dispute over a container, the contract is what counts.

What to write in your specification

A size-count specification comes down to five lines with numbers in them: the unit, the range, the reference weight, the tolerance and the inspection method. The values below are starting points to negotiate with the plant, not official standards.

Which exact lines should you require from the supplier?

1. One unit only: "Count expressed in pieces per pound (453.6 g) on net deglazed weight", or in pieces per kilo, but never a mix of the two from one line to the next.
2. Product form: HOSO, HLSO or PDTO spelled out in full, with the expected yield from raw material.
3. Range and average: for example 31/40, with a lot average that falls within the range.
4. Capped glazing: a declared maximum rate, measured by deglazing on arrival, with a price adjustment above it.
5. Inspection method: sample taken per master carton, count done on deglazed shrimp, allowed deviation written down, and a report sent with the shipment.

To hold the supplier to these lines all the way to the quay, buyers also need to know what happens at arrival: the SIVEP inspection at Le Havre checks sanitary compliance, not your count. Size count is therefore a contractual matter.

Count is also a price lever: each step up in size pushes up the price per kilo, as explained in large shrimp and their price per kilo. These lines become useful at the quoting stage: a FOB quote by count and format within 48 hours can only be compared line by line if the unit, glazing and tolerance are the same from one supplier to the next. This applies to 20' container volumes (MOQ 1×20' FCL, mixed products possible), not to buying by the case.

In the interest of transparency, my own Search Console figures for emg-seafood.fr (30 days to early September 2026) show 410 impressions and 4 clicks on our size count page. People are interested in the question, but few readers get as far as the contract line. This article is for them.

Verdict: which count to list, and on what terms

The count to add to your product range is the one you can check, not the biggest or the cheapest. Most Vietnamese Vannamei PDTO offers fall between 21/25 and 41/50; everything else is niche.

Should you stick to a single count?

I recommend listing two neighbouring counts (for example 26/30 and 31/40) in the same container rather than one, because mixed products are possible and it limits your exposure if a lot drifts. Avoid any offer that doesn't state the unit, the glazing or the tolerance. Worth testing on a first container: a single count with systematic deglazing checks on arrival at Le Havre or Antwerp, to measure the real gap between what was declared and what was delivered.

Before you compare any quotes, remember this: a count only means something when it's written with its unit, its reference weight and its tolerance.