How many large prawns is 100g?

December 8, 2025 •

4 min read

According to reputable seafood wholesalers, a large prawn typically weighs between 30 and 44 grams, meaning a standard 100g serving contains approximately 2 to 3 large prawns. However, the exact count depends heavily on the specific grading, the cooking method used, and whether the prawns are sold with heads and shells on or off.

Quick Summary

This guide details the factors influencing the number of large prawns in 100g, including commercial sizing grades, preparation methods, and accurate portioning for recipes and meals. It also offers a comparison table for different prawn sizes.

Key Points

Count Variation: The number of large prawns in 100g is not fixed, typically ranging from 2 to 4 depending on grading and preparation.
Grading System: Prawn size is categorized by the count per pound or kilogram; a lower count indicates a larger prawn.
Preparation Method: The weight of a prawn changes significantly if it's head-on or head-off, and whether it's raw or cooked.
Typical Sizing: A large prawn (grade 10/15) averages 30-44g, while extra-large (U10) is 45-55g.
Cooking Shrinkage: Prawns lose water during cooking, meaning 100g of cooked prawns will consist of more pieces than 100g of raw ones.
Check the Label: Always refer to the product packaging for the specific count or grade for the most accurate measurement.
Recipe Planning: The best prawn size for a recipe depends on the dish, with smaller prawns suited for salads and larger ones for grilling.

Understanding Prawn Sizing

Seafood sizing can be confusing, as it's not a universal standard and can vary between wholesalers, fishmongers, and countries. The most common method involves a 'count per pound' or 'count per kilogram' system, which indicates the number of individual prawns that make up a specified weight. A smaller count number, such as 10/15, signifies a larger prawn size, as fewer are needed to reach the full weight. For example, a prawn graded 10/15 will be larger than one graded 16/20.

Factors Affecting Prawn Count

Several variables influence the number of large prawns in a 100g portion:

Grading System: As seen in the count per pound system, different commercial grades determine the average weight of each prawn. A prawn designated simply as 'large' can fall into a range, not a single fixed weight.
Head-on vs. Head-off: The weight of the prawn's head and shell can significantly impact the final count. A prawn with its head on can weigh almost double what it does when peeled, so it's crucial to know how your prawns are processed. For example, 100g of head-on prawns will contain fewer individual pieces than 100g of peeled and deveined prawns.
Raw vs. Cooked: Prawns lose some water weight during cooking, which causes them to shrink in size. This means that 100g of cooked prawns will generally contain more individual pieces than 100g of raw prawns of the same grade.
Species of Prawn: The count can also vary depending on the prawn's species. Some varieties, like the Giant Tiger Prawn (Penaeus monodon), can reach considerable sizes, with even a single one weighing over 100g.

Practical Guide to 100g of Prawns

To determine the number of large prawns in 100g for a recipe, it's best to consider the grading. The following is an approximation based on common grading practices. For head-off and peeled large prawns, the count will be higher than for whole, raw prawns. For a rough culinary guide, 100g of cooked, peeled king prawns is often cited as 3-4 pieces.

Typical Count for 100g of Prawns

Based on common size ranges, here is what you can expect for 100g:

Extra-Large Prawns (U10): Often weighing 45-55g each, a 100g portion will contain approximately 1-2 prawns.
Large Prawns (10/15): With an average weight of 30-44g each, you can expect 2-3 large prawns in a 100g serving.
Medium-Large Prawns (16/20): Weighing between 23-29g each, 100g would contain about 3-4 prawns.
Medium Prawns (16/20 to 21/30): This versatile size can mean up to 5-6 prawns in 100g when cooked and peeled.

Portioning and Recipe Accuracy

When preparing a meal, knowing the count can help you plan your recipe and control portion sizes. For an appetizer like prawn cocktail, a larger count of medium prawns might be preferable, while a main course like grilled prawns would feature fewer, larger pieces for a more impressive display.

Comparison of Prawn Sizes and Count per 100g

This table provides a useful comparison of different prawn grades, illustrating the variety you can find when purchasing seafood. These numbers are approximations for raw, head-off prawns.


Prawn Grade (Count per Pound)	Weight Range (grams per prawn)	Approximate Count per 100g
U8 (Extra Extra Large)	56g to 75g	1-2
U10 (Extra Large)	45g to 55g	1-2
10/15 (Large)	30g to 44g	2-3
16/20 (Medium-Large)	23g to 29g	3-4
21/30 (Medium)	15g to 22g	4-6

How Prawn Weight Fluctuates

The total number of prawns in 100g can also be affected by how they are handled and prepared. If you buy frozen prawns, consider that the glaze (a thin layer of ice used for preservation) can add to the total weight. Once thawed and drained, the weight and count can change slightly. Always check the packaging for specific count or grade information if precision is important for your recipe.

The Importance of Grading

Professional chefs and seafood suppliers rely on specific grading for consistency. For the home cook, understanding these grades can prevent confusion and ensure you buy the right amount and size of prawns for your intended dish. Buying by weight is a more reliable method than relying on the number of prawns per pack, as the latter can be misleading without a specified size.

Conclusion

While a definitive answer to "how many large prawns is 100g?" varies based on several factors, a general guideline suggests 2 to 3 pieces, assuming a standard large prawn weighing between 30 and 44 grams. The ultimate count is influenced by the grading system, the prawns' preparation (head-on vs. head-off), and the species. By understanding these variables and checking the product's grade, you can more accurately measure your seafood for any culinary application, from a casual appetizer to a sophisticated main course.

For further reading on prawn sizing and seafood sourcing, the Sydney Fish Market offers valuable information on purchasing and storage tips.

Frequently Asked Questions

The number varies due to different commercial grading standards, whether the prawns are head-on or head-off, and whether they are raw or cooked. The average weight of a 'large' prawn is not a fixed universal standard.

Prawns are typically sized by the number of pieces per pound or kilogram. The packaging will usually display this grade (e.g., U10, 16/20). A smaller number means larger individual prawns.

Yes, it does. Prawns lose some weight during cooking due to water loss, which causes them to shrink. Therefore, 100g of cooked prawns will generally consist of more individual pieces than 100g of raw ones.

A large prawn, graded as 10/15 per pound, typically weighs between 30 and 44 grams. The weight can be affected by the species and whether it's whole or peeled.

Head-on prawns include the head and shell, which adds significant weight, so you will get fewer individual pieces per 100g. Head-off prawns are sold with the head already removed, resulting in a higher count per 100g.

While 100g is a healthy portion, it may be small for a main course. Many recipes recommend 150-200g of prepared prawns per person for an entrée, while 100g could be suitable for a starter.

For reputable information on seafood sizing, you can consult resources from professional seafood markets, like the Sydney Fish Market's purchasing tips, or government food standards agencies.