A Home Cook’s Guide to Buying Frozen Prawns in the UK

Buying frozen prawns online should be simple. Yet, many of us have felt the disappointment of opening a bag to find tiny, icy prawns that shrink to nothing in the pan, or worse, turn rubbery the moment they hit the heat. The convenience of having a bag of prawns in the freezer is often undermined by confusing packaging and marketing jargon.

As the Joybuy Product Recommendation Officer, my role is to help you navigate these choices. Before you add a pack to your basket, let's look at the common pitfalls that can lead to a disappointing meal and how to avoid them.

The 3 Traps to Avoid When Buying Frozen Prawns

1. The Ice Glaze Illusion: You see a large 1kg bag at a great price, but when you thaw the contents, you're left with a much smaller amount of actual prawns. This is due to "glazing," a layer of ice applied to protect the prawns. While some glazing is necessary, excessive amounts mean you are paying for frozen water. Always check for the net weight or "drained weight" to understand how many prawns you are actually getting.
2. The "Jumbo" Size Myth: Terms like "Jumbo" or "King" are marketing descriptions, not official sizes. One brand's "jumbo" might be another's "medium." This leads to inconsistency and makes it hard to know if you're getting good value. The true measure of size is the count per pound (lb) or kilogram (kg), which we'll cover below.
3. The Raw vs. Cooked Mismatch: Accidentally buying pre-cooked prawns for a stir-fry or curry is a common mistake. Adding them to a hot pan will overcook them, resulting in a tough, rubbery texture. Conversely, buying raw prawns for a quick prawn cocktail means you have an extra cooking step you weren't planning for.

Decoding the Label: Key Factors for Your Selection

To ensure you get the right product for your recipe, focus on these three specifications. They provide a much clearer picture of quality and suitability than any marketing slogan.

1. Understanding Prawn Sizing: The Numbers Game

The most reliable indicator of a prawn's size is the count number on the packaging, such as 16/20 or 31/40.

• What it means: This range indicates the number of prawns you can expect to find per pound (lb).
• How to read it: A lower number signifies larger prawns. For example, a bag of 8/12 jumbo king prawns contains 8 to 12 very large prawns per pound, making them ideal for grilling or as a centrepiece. A bag of 31/40 prawns will contain smaller prawns, which are well-suited for curries, pasta dishes or fried rice.

2. Raw vs. Cooked Prawns: Choosing for Your Dish

This is the most critical choice for texture and flavour.

• Raw Prawns: Usually grey or translucent, these are essential for dishes where the prawns are cooked as part of the recipe. Raw king prawns will absorb the flavours of your sauce, marinade or spices, and when cooked correctly, they have a tender, succulent bite. They are the go-to choice for prawns for curry, paella and garlic prawn linguine.
• Cooked Prawns: Typically pink, these are ready to eat once thawed. They are perfect for cold dishes like prawn cocktails, salads and sandwiches. You can add them to hot dishes at the very end of cooking, just to warm them through, but be careful not to overcook them.

3. Shell-On vs. Peeled & Deveined (P&D): Flavour vs. Convenience

• Shell on prawns: Keeping the shell on during cooking protects the delicate meat, resulting in a juicier, more flavourful prawn. The shells and heads are also excellent for making a rich, flavourful seafood stock. This option requires more prep work but rewards you with superior taste.
• Peeled and deveined prawns (P&D): This is the ultimate in convenience. The shell and digestive tract (the "vein") have been removed, meaning they are ready to cook straight from the bag. They are a fantastic time-saver for quick weeknight meals.

Another term to look for is IQF (Individually Quick Frozen). This means each prawn is frozen separately, not in a solid block. This preserves the texture and allows you to take out only the portion you need, keeping the rest perfectly frozen for another day.

Our Top Product Recommendations

To help you choose, we've matched a few options to different home-cooking needs, keeping our selection criteria in mind.

MATCH FOR: The Weeknight Meal Planner

ROYAL STAR Raw Peeled & Deveined Prawn IQF (L-26/30) 700g net

Why This Fits Their Persona: This user needs a quick, no-fuss protein for stir-fries, curries or pasta. These raw, peeled and deveined prawns eliminate prep time, allowing a healthy meal to come together in minutes.

How It Avoids the Trap

It clearly states the 700g net weight and the 26/30 size grade, avoiding the ice glaze and "jumbo" traps. Being raw, it's perfect for cooking from scratch, preventing rubbery results.

Key Advantage & Pros

IQF frozen for easy portioning. Fully peeled and deveined for maximum convenience.

MATCH FOR: The Seafood Connoisseur

Freshwater Headless Shell-on 8-12/lb Block Raw Prawns 700g

Why This Fits Their Persona: This cook prioritises flavour and presentation for special occasion dishes like a BBQ, paella or a luxurious curry. They understand that the shell locks in moisture and taste.

How It Avoids the Trap

The size is clearly defined as a premium 8-12 per pound, far more precise than "jumbo." The shell-on format is a deliberate feature for flavour, not an oversight.

Key Advantage & Pros

Truly large, restaurant-quality size. The shell-on format delivers a more succulent texture and richer seafood flavour.

MATCH FOR: The Ultimate Convenience Seeker

Aqua Hawk IQF Cooked Peeled Cut Deveined TAIL OFF Prawns Vannamei 31/40 (350g Net)

Why This Fits Their Persona: This user wants prawns for a salad, sandwich or classic prawn cocktail with zero cooking required. They need a product that is ready to eat after thawing.

How It Avoids the Trap

It is explicitly sold as cooked prawns, eliminating any confusion. The 350g net weight is clearly stated, so you know exactly what you're getting for your money.

Key Advantage & Pros

Ready to eat once defrosted. Fully peeled, deveined and tail-off for absolutely no preparation.

Frequently Asked Questions

What do the numbers on a bag of frozen prawns mean (e.g., 31/40)?

This is the industry-standard size grading. It tells you the approximate number of individual prawns per pound (lb). A smaller number range, like 16/20, means you are getting larger prawns. A higher number range, like 41/50, indicates smaller prawns, which are often more economical and suitable for mixing into dishes.

Should I defrost frozen prawns before cooking?

For the most even cooking and texture, it is generally recommended to defrost raw prawns before cooking. The two main methods are:

1. Overnight in the fridge: Place the prawns in a covered bowl in the refrigerator for several hours or overnight.
2. Under cold running water: For a quicker thaw, place the frozen prawns in a colander and run cold water over them for 5-10 minutes until defrosted. Some recipes, particularly for boiling, may instruct you to cook from frozen, so always check the package instructions.

Can I use frozen prawns for a curry?

Yes, frozen prawns are an excellent choice for curry. For the best results, use raw, peeled and deveined prawns. Add them to the curry sauce towards the end of the cooking time (usually the last 3-5 minutes). They will cook quickly in the hot sauce, absorb the flavours and remain tender and succulent. Avoid using pre-cooked prawns, as they are likely to become tough.