Picture this: you're calculating food costs using the weight on your invoice, but half that product ends up in the trash bin. Most kitchens forget about the inevitable loss from peels, bones and trim waste. That gap between what you buy and what actually hits the plate? It's costing you serious money.
What is gross portion weight?
The gross portion weight is the total weight of an ingredient as you purchase it, including all non-edible parts. This is the weight on your invoice and what you pay for.
💡 Example gross weights:
- Whole chicken: 1,200 grams (including bones, skin, neck)
- Unpeeled potatoes: 200 grams per portion
- Whole fish: 300 grams (including head, spine, scales)
- Unpeeled shrimp: 150 grams
What is net portion weight?
The net portion weight is the weight of the ingredient that actually ends up on the plate. This is after removing all non-edible parts like peels, bones, pits and after cooking (weight loss from moisture).
💡 Example net weights:
- Chicken breast from whole chicken: 400 grams (from 1,200g)
- Peeled potatoes: 160 grams (from 200g)
- Fish fillet: 120 grams (from 300g whole fish)
- Peeled shrimp: 75 grams (from 150g)
Why this difference is crucial for your cost price
You pay for the gross weight, but serve the net weight. If you calculate your cost price using the gross weight, you're calculating too low and losing money on every plate.
⚠️ Watch out:
Many kitchens calculate using the purchase price per kilo and the gross weight. This makes your food cost appear lower than it actually is. Your actual cost price is always higher than your purchase price per kilo.
Calculate yield
The yield is the percentage of usable product you have left after processing. Calculate it like this:
Yield % = (Net weight ÷ Gross weight) × 100
💡 Example yield calculation:
You buy 2 kg whole salmon for €18 per kilo. After filleting you have 1.1 kg fillet left.
- Gross weight: 2,000 grams
- Net weight: 1,100 grams
- Yield: (1,100 ÷ 2,000) × 100 = 55%
Actual fillet price: €18 ÷ 0.55 = €32.73 per kilo
Calculate actual cost price
To know your real cost price, you need to adjust the purchase price for yield:
Actual price per kilo = Purchase price ÷ (Yield % ÷ 100)
- Buy chicken for €8/kg with 35% yield? Then you pay €22.86/kg for the meat
- Shrimp €24/kg with 50% yield? Actually €48/kg peeled
- Potatoes €2/kg with 80% yield? Actually €2.50/kg peeled
Typical yields per product
After managing kitchen operations for nearly a decade, I've learned that you can use these percentages as a starting point, but always test in your own kitchen:
- Fish (whole to fillet): 45-55%
- Chicken (whole to meat): 30-40%
- Beef (with bone): 75-85%
- Potatoes (peeling): 75-85%
- Onions (peeling): 88-92%
- Carrots (peeling): 80-90%
⚠️ Watch out:
These percentages vary by supplier, season and quality. Measure your own yield by weighing the gross and net weight a few times. Tools like KitchenNmbrs can help track these variations over time.
How do you calculate net portion weight? (step by step)
Measure the gross purchase weight
Weigh the product as you purchase it, including all non-edible parts. Note this weight and the purchase price per kilo.
Process the product and weigh the net weight
Remove all non-edible parts (peels, bones, etc.) and weigh what's left. This is your net weight that actually ends up on the plate.
Calculate the yield and actual cost price
Divide the net weight by the gross weight for your yield percentage. Then divide your purchase price by this yield for the actual cost price per kilo.
✨ Pro tip
Track waste from your 3 most expensive proteins for exactly 10 days - weigh every bone, skin, and trim piece. You'll discover which supplier gives you the worst yields and can renegotiate or switch.
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
Do I need to calculate the yield for every ingredient?
Not for everything. Focus first on your most expensive ingredients and products with a lot of waste. Products you buy ready-made (fillets, peeled vegetables) have almost 100% yield.
Does yield change per season?
Yes, especially with vegetables and fruit. Potatoes have thicker peels in spring, fish can be fattier in certain seasons. Check your yield a couple times a year.
What about weight loss from cooking?
Meat and fish lose 15-25% weight from cooking (moisture evaporates). Factor this into your net weight if you want to know the cost price per served portion.
Can I use yields from the internet?
As a starting point yes, but measure it yourself. Every knife cuts differently, every supplier has different quality. Your own yield is always more reliable.
⚠️ 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.
Standardize portions, stabilize margins
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