Think of portion sizing like fitting puzzle pieces together. Too big and your profit margins crumble, too small and customers walk away unsatisfied. The sweet spot lies in mathematical precision that balances your financial goals with guest expectations.
Start with your desired selling price and food cost
Before determining portion size, you need clarity on what you want to earn from each dish. Most restaurants target food costs between 28% and 35%.
? Example:
You want to sell a steak for €32.00 (incl. 9% VAT) with 30% food cost:
- Selling price excl. VAT: €32.00 / 1.09 = €29.36
- Maximum ingredient costs: €29.36 × 0.30 = €8.81
You've got €8.81 budget for all ingredients on this plate.
Calculate the cost of all side dishes
First, add up costs for garnishes, sauces, vegetables and other ingredients. What remains becomes your main ingredient budget.
? Example steak:
Budget: €8.81. Other ingredients:
- Potatoes: €0.45
- Vegetables: €0.80
- Sauce: €0.65
- Butter/oil: €0.35
- Seasonings: €0.15
Total side dishes: €2.40. Budget for meat: €8.81 - €2.40 = €6.41
Determine the portion size of the main ingredient
Divide your main ingredient budget by the purchase price per kilo. This reveals your maximum portion size in grams. I've seen restaurants lose €200-400 monthly by skipping this calculation and just eyeballing portions.
Formula: Portion size (grams) = Budget main ingredient / (Purchase price per kg / 1000)
? Calculation:
Entrecote costs €28.00 per kilo. Budget: €6.41
- Price per gram: €28.00 / 1000 = €0.028
- Maximum portion: €6.41 / €0.028 = 229 grams
You can serve a maximum of 229 grams of entrecote within your budget.
⚠️ Note:
Always calculate with actual purchase price. With whole meat there's also trimming loss. A whole entrecote at €24/kg often becomes €32/kg in portions after boning.
Check if the portion size is realistic
Compare your calculated portion size with what's standard in your restaurant type. Portions that are too small disappoint guests, portions that are too large drain profits.
- Fine dining: 180-220 grams meat
- Casual dining: 200-250 grams meat
- Bistro: 220-280 grams meat
- Steakhouse: 250-400 grams meat
⚠️ Note:
If your calculated portion is much smaller than standard, you need to choose: higher selling price, lower food cost target, or cheaper ingredient.
Adjust for trimming loss and waste
With fresh products you process yourself, calculate trimming loss. This makes the product more expensive than the purchase price suggests.
? Example trimming loss:
Whole salmon €18/kg, 45% trimming loss:
- Yield: 55%
- Actual fillet price: €18 / 0.55 = €32.73/kg
- With budget €6.41: maximum 196 grams fillet
Trimming loss significantly reduces your possible portion size.
Standardize your portions
Once you've determined the ideal portion size, ensure every chef uses it consistently. Variation in portion sizes destroys your cost price calculation. And tools like KitchenNmbrs can help track these variations automatically.
- Use scales in the kitchen
- Train your team on exact gram weights
- Regularly check if portions are correct
- Document portion sizes in your recipes
How do you calculate the ideal portion size? (step by step)
Determine your budget for ingredients
Multiply your selling price (excl. VAT) by your desired food cost percentage. At €29.36 selling price and 30% food cost you have €8.81 budget for all ingredients.
Subtract the costs of side dishes
Add up all costs of garnishes, sauces, vegetables and other ingredients. Subtract this from your total budget. The remainder is available for your main ingredient.
Calculate the maximum portion size
Divide your budget for the main ingredient by the price per gram. With €6.41 budget and meat at €0.028/gram you get a maximum portion of 229 grams.
Correct for trimming loss
With whole products that you process yourself, divide by the yield percentage. 20% trimming loss means 80% yield, so divide by 0.80.
Compare with market standard
Check if your calculated portion is realistic for your type of restaurant. Portions that are too small make guests unhappy, portions that are too large cost money.
✨ Pro tip
Weigh your actual portions for 48 hours straight on your top 3 revenue-generating dishes. You'll discover portion creep that's likely costing you 2-4% in food cost variance.
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Frequently asked questions
What if my calculated portion is too small for my restaurant type?
How do I handle trimming loss with expensive proteins like wagyu beef?
Should I recalculate portions when my supplier changes prices mid-contract?
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
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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