A 2kg salmon bought at €18/kg yields just 1.1kg of usable fillet, pushing your real cost to €32.73/kg. Most restaurant owners price their dishes using the whole fish cost, creating a hidden profit leak. Understanding net cost price after cutting loss prevents this expensive mistake.
Why the purchase price misleads you
You purchase whole salmon at €18.00 per kilo. After filleting, you're left with 1.1 kg of usable fillet from that 2 kg fish. So you're actually paying much more for the final product than the purchase price indicates.
⚠️ Watch out:
Many business owners calculate their menu price based on the purchase price of whole fish. Your food cost won't balance and you'll lose money on every single dish.
The formula for net cost price
You calculate the real cost price by dividing the purchase price by the yield percentage:
Net cost price = Purchase price ÷ (Yield % ÷ 100)
Yield equals 100% minus the cutting loss percentage.
💡 Example:
Whole salmon of 2 kg for €18.00/kg:
- Purchase price: €18.00/kg
- After filleting: 1.1 kg fillet (45% cutting loss)
- Yield: 55%
Net cost price fillet: €18.00 ÷ 0.55 = €32.73/kg
Typical cutting loss per fish species
Cutting loss varies by fish species and processing method:
- Salmon (whole to fillet): 40-50% loss
- Sea bass (whole to fillet): 45-55% loss
- Tuna (whole to fillet): 35-45% loss
- Flatfish (whole to fillet): 50-60% loss
- Shrimp (unpeeled to peeled): 35-50% loss
💡 Example calculation:
You buy 5 kg sea bass for €22.00/kg:
- Purchase value: 5 kg × €22.00 = €110.00
- After filleting: 2.5 kg fillet (50% loss)
- Net cost price: €110.00 ÷ 2.5 kg = €44.00/kg fillet
Or using the formula: €22.00 ÷ 0.50 = €44.00/kg
What to do with by-products
Some parts of the fish can still generate value:
- Fish bones and head: For stock or sale to supplier
- Trimmings: For tartare, fish cakes or staff meals
- Skin: Fried chips as garnish
Subtract the value of by-products from your purchase price before calculating the net cost price.
💡 Example with by-products:
5 kg salmon at €18.00/kg = €90.00 purchase:
- Revenue from bones for stock: €15.00
- Net purchase price: €90.00 - €15.00 = €75.00
- 2.5 kg fillet after processing
Net cost price: €75.00 ÷ 2.5 kg = €30.00/kg fillet
Impact on your food cost
The difference between purchase price and net cost price has a major impact on your profitability. If you calculate with €18.00/kg while you're actually paying €32.73/kg, your food cost is much higher than you think. This is a pattern we see repeatedly in restaurant financials - operators underestimating their true protein costs by 40-60%.
⚠️ Watch out:
For a 200 gram salmon fillet, the difference between calculating with purchase price (€3.60) and net cost price (€6.55) is €2.95 per portion. That can mean the difference between profit and loss.
Tracking cost prices digitally
Manually tracking all cost prices and yields takes considerable time. A system like KitchenNmbrs helps you to:
- Record cutting losses per ingredient
- Automatically calculate net cost prices
- Track your food cost per dish
- Immediately see what price changes mean for your margin
How do you calculate the net cost price of fish? (step by step)
Measure the weight before and after processing
Weigh the whole fish upon arrival and weigh again after filleting. Note both weights to calculate the exact yield.
Calculate the cutting loss percentage
Subtract the final weight from the initial weight, divide by initial weight and multiply by 100. This gives you the loss percentage.
Calculate the yield
Subtract the loss percentage from 100%. A loss of 45% means a yield of 55%.
Divide the purchase price by the yield
Divide the original price per kilo by the yield (as a decimal). At €18.00/kg and 55% yield: €18.00 ÷ 0.55 = €32.73/kg.
Subtract value of by-products (if applicable)
If you can use or sell bones, head or trimmings, subtract this value from your purchase price before you calculate the net cost price.
✨ Pro tip
Weigh your next 3 whole fish deliveries before and after filleting to establish your baseline yield. Even a 5% improvement in filleting technique can save €200+ monthly on a typical restaurant's fish purchases.
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
Can't I just estimate what fish costs after filleting?
Estimating often leads to errors of 20-30%. The difference between 40% and 50% cutting loss means €6.00 difference per kilo. With large volumes this adds up to hundreds of euros monthly.
Do I need to weigh every fish or can I use averages?
Start by weighing a few deliveries to determine your average. Check this monthly, because yield can vary by season and supplier.
What about frozen fish versus fresh fish?
Frozen fish often has less cutting loss because head and innards are already removed. But watch out for ice glaze - it counts in the weight but not in your end product.
What if my supplier raises the price?
Update your net cost price calculation immediately. A €2.00/kg increase for whole fish means €4.00/kg more for your fillet at 50% yield.
Should I factor in labor costs for filleting time?
Absolutely. If filleting takes 15 minutes at €25/hour labor cost, add €6.25 to your fish cost. This often adds another 10-15% to your true cost per portion.
How do I handle different fish sizes affecting yield?
Smaller fish typically have higher cutting loss percentages due to proportionally larger heads and bones. Track yields separately for different size categories if you notice significant variations.
Can seasonal changes affect my cutting loss calculations?
Yes, fish condition varies seasonally - spawning fish have less meat, winter fish more fat content. Recalculate your yields quarterly to maintain accuracy.
⚠️ 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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