How prawn count sizes work
Prawn and shrimp sizing in international trade is expressed as a count per pound — the number of prawns that weigh one pound (approximately 454 g). A lower count means larger, heavier individual prawns; a higher count means smaller, lighter prawns. The format is written as a range (e.g., 16/20) indicating the minimum and maximum number of prawns in one pound.
For tiger prawns (Penaeus monodon — Black Tiger Prawn, or Penaeus vannamei — Pacific White/Vannamei Prawn, which is commonly marketed as tiger prawn in UK B2B trade), the most commercially significant UK wholesale grades are:
| Count Grade | Approx. Weight Each | Size Description | Primary Application |
|---|---|---|---|
| U/10 | 45 g+ | Colossal | Premium display, BBQ centrepiece |
| U/15 | 30–45 g | Extra Colossal | Premium food-service, display |
| 16/20 | 23–28 g | Extra Jumbo | Premium restaurant, high-end retail |
| 21/25 | 18–22 g | Jumbo | Restaurant starters, grills |
| 26/30 | 15–18 g | Extra Large | Food-service, catering, retail |
| 31/40 | 11–15 g | Large | Catering, ready meals, stir-fry |
| 41/50 | 9–11 g | Medium | Volume catering, processing |
| 51/60 | 7–9 g | Small / Medium | Processing, ready meals |
Understanding 11/20 — the “colossal” grade
The 11/20 count — sometimes written as 11–20 count — means between 11 and 20 prawns make up one pound in weight. This corresponds to individual prawn weights of approximately 23–41 g for headless shell-on (HLSO) or head-on shell-on (HOSO) product, though exact weight depends on the form (shell-on vs peeled, head-on vs headless).
In practice, the 11/20 grade spans a broad range and is often split into sub-grades (11/15 and 16/20) by buyers who need more precise portion control. The 16/20 sub-grade — 16 to 20 prawns per pound, approximately 23–28 g each HLSO — is the most common premium restaurant specification in the UK, as it delivers a visually impressive, meaty prawn for grilling, tiger prawn cocktail, tempura and pan-fry applications.
Understanding 21/30 — the food-service standard
The 21/30 grade (21–30 prawns per pound, approximately 15–22 g each HLSO) is the workhorse of the UK food-service prawn market. It is large enough to present well on the plate, cost-effective enough for volume catering, and the right size for most standard food-service applications:
- Prawn cocktail starters (peeled, chilled)
- Prawn dishes in restaurants (garlic butter prawns, prawn linguine)
- Catering packs for events and hospitality
- Retail packs marketed as “large prawns”
- Sushi, prawn nigiri and Asian-style cooked prawn dishes
Understanding 31/40 — the volume catering grade
The 31/40 grade (31–40 prawns per pound, approximately 11–15 g each HLSO) is the primary volume catering and ready meal specification. Individual prawns are smaller — roughly half the weight of a 16/20 — which means:
- Lower cost per kg vs 16/20 or 21/30
- More prawns per portion — useful for dishes where prawns are a component rather than the centrepiece
- Suitable for stir-fry, prawn fried rice, ready meal production, poppadum toppings and vol-au-vents
- Standard specification for prawn cocktail mix in volume catering
HLSO vs HOSO vs PD vs PUD — format clarification
Count sizes apply to the prawn in a specific processed form. Common formats and their abbreviations:
- HOSO — Head-on, shell-on. Whole prawn including head and shell. Count applies to the whole animal. Popular for Asian food-service, BBQ display, fresh chilled market.
- HLSO — Headless, shell-on. Head removed, shell intact. The most common frozen import specification for UK wholesale. Count applies per pound in this form.
- EZP / EZPD — Easy-peel. Shell split along the back and deveined but shell not fully removed. Popular for retail and premium food-service.
- PD — Peeled and deveined. Shell and intestinal tract removed. Standard for ready meals, catering packs and pre-portioned food-service.
- PUD — Peeled, undeveined. Shell off, vein not removed. Cheaper, used in some processing and cooking applications.
A count size is specific to the form — 21/30 HLSO prawns will not have the same individual prawn weight as 21/30 PD prawns (peeled prawns are lighter due to shell removal). Always specify both count and form when ordering.
Black tiger prawn vs vannamei: does it matter for your count size?
Black tiger prawn (Penaeus monodon) grows larger than vannamei and is available in colossal and jumbo grades that vannamei cannot match. If you are specifying U/10 or U/15 grades, you are likely ordering black tiger prawn. For 21/30 and above, both species can fill the grade — but flavour, texture and price differ:
- Black tiger prawn: firmer texture, more pronounced “prawn flavour”, higher price point, traditionally associated with premium quality
- Vannamei: milder flavour, softer texture, more consistent supply and lower price — the dominant species in global aquaculture and UK wholesale volumes
Brookstone Trade supplies fresh tiger prawns wholesale UK in multiple count grades. Contact us to discuss species, count grade, form and volume.