Ever wonder why your fish dishes aren't hitting target food costs? Cooking loss can eat up to 25% of your fish's original weight, depending on type and prep method. Most chefs forget to factor this into their pricing, which means they're bleeding money on every portion.
What is cooking loss in fish?
Cooking loss happens when moisture evaporates during cooking. Fish contains tons of water, so this loss can be massive. The exact amount depends on your fish type and how you're cooking it.
💡 Example:
You buy 1 kg of salmon fillet for €24.00. After pan-frying, the fish weighs 800 grams.
- Raw weight: 1000 grams
- Cooked weight: 800 grams
- Cooking loss: 200 grams (20%)
So you have 20% cooking loss.
Formula for cooking loss percentage
The math is straightforward but absolutely critical for accurate food costs:
Cooking loss % = ((Raw weight - Cooked weight) / Raw weight) × 100
💡 Example calculation:
Cod fillet: 250 grams raw becomes 200 grams cooked
- Cooking loss: (250 - 200) / 250 × 100
- Cooking loss: 50 / 250 × 100
- Cooking loss: 20%
So you need to buy 25% more to end up with 200 grams of cooked fish.
Typical cooking loss per fish type
Different fish varieties shrink at different rates. Here's what you can expect:
- Salmon: 15-20% (fatty fish retains more moisture)
- Cod: 20-25% (lean fish loses more water)
- Sole: 15-20% (flat fish, moderate shrinkage)
- Tuna: 25-30% (varies wildly based on preparation)
- Dorade: 18-22% (standard loss range)
⚠️ Important:
Always test your own cooking loss. It changes based on supplier, season, and prep method. Grilling produces different results than poaching.
Impact on your food cost
Cooking loss drives up your real per-kilo cost. You're buying more fish than what actually reaches the plate, so your portions cost more than you think.
💡 Food cost impact:
Cod €18/kg, 22% cooking loss, portion 180 grams cooked
- Actual price: €18 / 0.78 = €23.08/kg cooked
- Portion cost: 0.18 kg × €23.08 = €4.15
- Without accounting for cooking loss: €18 × 0.18 = €3.24
Difference: €0.91 per portion - that adds up!
Practical measurement tips
Track cooking loss systematically to nail down accurate food costs. It's the kind of thing you only learn after closing your first month at a loss - trust me on this one.
- Always weigh identical amounts (like 500 grams)
- Test at different times (fish quality varies)
- Record each prep method separately (pan vs grill vs poach)
- Factor in seasonal changes (spawning season affects moisture)
Tools like KitchenNmbrs let you log your measured cooking losses by fish type and prep method. The system automatically adjusts your portion costs based on real data.
How do you calculate cooking loss of fish? (step by step)
Weigh the raw fish
Weigh a portion of raw fish before you start cooking. Note this weight as your starting weight. Preferably use a digital kitchen scale for accuracy.
Prepare the fish as usual
Cook, pan-fry, or grill the fish the way you normally do in your kitchen. Don't change anything about your standard preparation method, because you want to measure the real cooking loss.
Weigh the cooked fish
Weigh the fish immediately after cooking, before it cools down. Note this weight as your final weight. Leave out any sauce or garnish when weighing.
Calculate the loss percentage
Use the formula: ((Raw weight - Cooked weight) / Raw weight) × 100. This gives you the cooking loss as a percentage that you can use in your food cost calculations.
✨ Pro tip
Weigh your raw and cooked fish for 7 consecutive days on your signature fish dish. That real data will give you a precise cooking loss percentage that accounts for your specific equipment and technique.
Calculate this yourself?
In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.
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Frequently asked questions
Does cooking loss differ by preparation method?
Absolutely. Grilling and pan-frying typically cause 20-25% loss, while poaching results in 15-20%. Deep-frying can hit 30% loss due to high temperatures.
Should I include cooking loss in my selling price?
You must, or you'll lose money on every fish portion. Calculate portions based on cooked weight, but price using raw purchase cost plus cooking loss factor.
How often should I remeasure cooking loss?
Test at least quarterly, or whenever you switch suppliers. Fish varies by season and source, so regular checks keep your costs accurate.
Is cooking loss the same as trimming loss?
No, they're separate losses you need to track. Trimming loss happens when filleting whole fish, cooking loss occurs during preparation of the fillet.
Can I prevent cooking loss?
Only partially. Lower temps and shorter cooking times help, but may compromise taste and food safety. Better to calculate it accurately than try preventing it.
What's the biggest mistake restaurants make with fish cooking loss?
Using theoretical percentages instead of measuring their own. Every kitchen cooks differently, and those small differences add up to major cost variations over time.
⚠️ EU Regulation 1169/2011 — Allergen Information — https://eur-lex.europa.eu/eli/reg/2011/1169/oj
The allergen information on this page is based on EU Regulation 1169/2011. Recipes and ingredients may vary by supplier. Always verify current allergen information with your supplier and communicate this correctly to your guests. KitchenNmbrs is not liable for allergic reactions.
In the UK, the FSA enforces allergen regulations under the Food Information Regulations 2014.
📚 Sources consulted
- EU Verordening 852/2004 — Levensmiddelenhygiëne (2004) — Official source
- EU Verordening 853/2004 — Hygiënevoorschriften voor levensmiddelen van dierlijke oorsprong (2004) — Official source
- EU Verordening 1169/2011 — Voedselinformatie aan consumenten (2011) — Official source
- NVWA — Hygiënecode voor de horeca (2024) — Official source
- NVWA — Allergenen in voedsel (2024) — Official source
- Codex Alimentarius — International Food Standards (2024) — Official source
- FSA — Safer food, better business (HACCP) (2024) — Official source
- BVL — Lebensmittelhygiene (HACCP) (2024) — Official source
- Warenwetbesluit Bereiding en behandeling van levensmiddelen (2024) — Official source
- WHO — Foodborne diseases estimates (2024) — Official source
Food Standards Agency (FSA) — https://www.food.gov.uk
The HACCP standards shown in this application are for informational purposes only. KitchenNmbrs does not guarantee that displayed values are current or complete. Always consult the FSA or your local authority for the latest regulations.
Written by
Jeffrey Smit
Founder & CEO of KitchenNmbrs
Jeffrey Smit built KitchenNmbrs from 8 years of hands-on experience as kitchen manager at 1NUL8 Group in Rotterdam. His mission: give every restaurant owner control over food cost.
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