Every 20-gram difference in portion weight can cost you thousands annually. Most restaurant owners eyeball their portions, but that guesswork destroys profit margins. Here's how to calculate exact portion weights that protect your bottom line.
Why portion weight is crucial for your profit
A portion of 200 grams instead of 180 grams seems like nothing. But with a steak at €24 per kilo, that's €0.48 extra cost per plate. With 100 steaks per week, you lose €2,496 per year.
And it's not just about meat. Fish, vegetables, and side dishes — every gram eats into your margins.
The basic formula for portion weight
The ideal portion weight depends on three factors:
- Your desired food cost percentage (usually 28-35%)
- Your selling price (excluding VAT)
- The purchase price per kilo of the main ingredient
? Formula:
Max portion weight = (Selling price excl. VAT × Food cost %) ÷ Purchase price per kg
This applies to the main ingredient. Add side dishes separately.
Calculating with the main ingredient
Always start with your main ingredient — it typically accounts for 60-80% of your ingredient costs.
? Steak example:
- Menu price: €32.00 incl. VAT
- Selling price excl. VAT: €32.00 ÷ 1.09 = €29.36
- Desired food cost: 30%
- Beef purchase price: €18.00/kg
Calculation: (€29.36 × 0.30) ÷ €18.00 = 0.49 kg = 490 grams
That's way too much for one portion. So you'll need less meat or higher prices.
Including side dishes in the calculation
Your main ingredient isn't your only cost. Factor in your accompaniments too:
- Vegetables and garnish: €1.50-€3.00 per portion
- Sauces and butter: €0.50-€1.50 per portion
- Potatoes/pasta/rice: €0.80-€2.00 per portion
? Complete calculation example:
- Total budget for ingredients: €8.81 (30% of €29.36)
- Side dishes: €3.50
- Available for main ingredient: €8.81 - €3.50 = €5.31
Ideal beef portion weight: €5.31 ÷ €18.00 = 0.295 kg = 295 grams
Adjustments for trimming loss
Don't forget: with fish and meat, you've got trimming loss. You buy more than what hits the plate.
⚠️ Watch out:
With 20% trimming loss, your actual purchase price jumps. €18.00 per kilo becomes €18.00 ÷ 0.80 = €22.50 per kilo of usable meat.
Practical portion weights by product category
Based on real restaurant P&L data, these weights work for most establishments:
- Beef/pork: 180-250 grams
- Chicken (fillet): 150-200 grams
- Fish (fillet): 140-180 grams
- Vegetarian main course: 200-300 grams
Use this as a sanity check: if your calculated weight falls way outside these ranges, something's wrong with your pricing or food cost targets.
Testing and adjusting in practice
Calculate your ideal portion weight, but test it in the kitchen too:
- Prepare the dish with the calculated weight
- Check if it looks satisfying on the plate
- Get feedback from your team and test guests
Portions that are too small create unhappy guests. But portions that are too large kill your profit. You need the sweet spot.
How do you calculate the ideal portion weight? (step by step)
Determine your total ingredient budget
Calculate your selling price excluding VAT and multiply by your desired food cost percentage. At €32 incl. VAT and 30% food cost: (€32 ÷ 1.09) × 0.30 = €8.81 total budget.
Subtract the cost of side dishes
Calculate what vegetables, sauces, garnish, and side dishes cost. Subtract this from your total budget. What's left is available for your main ingredient.
Calculate the maximum portion weight
Divide your remaining budget by the purchase price per kilo of your main ingredient. Don't forget to factor in trimming loss: with 20% loss, divide by 0.80 instead of 1.00.
✨ Pro tip
Calculate portion weights for your top 5 main courses within the next 48 hours. These dishes drive 60-70% of your food cost, so getting them right immediately impacts your bottom line.
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
What if my calculated portion weight seems too small?
Should I use different weights for lunch and dinner?
How often should I recalculate my portion weights?
What if my chef says the portions are too small?
⚠️ 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
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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