Managing food costs is like walking a tightrope - you need perfect balance between rising ingredient prices on one side and customer satisfaction on the other. When purchase prices jump but you strategically reduce portions, your margin doesn't have to suffer. The trick lies in calculating the exact portion size that keeps both your profits and your guests happy.
The formula for adjusted margin
When purchase prices climb and portions shrink, here's your calculation:
New cost per portion = (New purchase price per kg × New portion size in kg)
New food cost % = (New cost per portion / Selling price excl. VAT) × 100
💡 Example:
Your 250 gram steak jumped from €18/kg to €22/kg (+22%). You're testing 220 gram portions:
- Original situation: €18/kg × 0.25 kg = €4.50 per portion
- Adjusted situation: €22/kg × 0.22 kg = €4.84 per portion
- Cost rises by just €0.34 instead of €1.00
At €32 selling price: food cost moves from 31.1% to 33.5%
What flies with guests?
The skill is trimming portions without triggering complaints or empty looks. Typical adjustments that work:
- Meat/fish: 10-15% reduction typically stays under the radar
- Side dishes: Up to 20% less rarely gets noticed
- Sauces: Portion size can drop 25% without issues
- Garnish: Visually crucial, but actual weight matters less
⚠️ Heads up:
Don't slash more than 20% in one go. Regulars will spot dramatic changes. Roll it out slowly over 2-3 months instead.
Alternative strategies
Beyond tweaking portion size, you've got other moves to shield your margin:
- Recipe makeovers: Swap pricey ingredients for budget-friendly alternatives
- Supplier shopping: Hunt for better prices without sacrificing quality
- Menu price bumps: A €1-2 increase often goes unnoticed compared to skimpy portions
- Seasonal pivots: Embrace cheaper seasonal ingredients
💡 Example calculation:
Salmon rockets from €24/kg to €28/kg. You're testing 160g instead of 180g portions:
- Original cost: €24 × 0.18 = €4.32
- New cost (same portion): €28 × 0.18 = €5.04
- New cost (trimmed portion): €28 × 0.16 = €4.48
Result: just €0.16 cost bump instead of €0.72
Communication with your team
Train your staff on the updated portion sizes. Deploy portioning tools like scales or measuring cups for consistency. From tracking this across dozens of restaurants, I've seen chefs who portion "by eye" accidentally stick to old generous servings.
Update your recipes in a system so everyone follows identical portion sizes and you automatically track the new food cost.
Monitor the results
Watch closely during the first month after changes:
- Portion size complaints
- Shifts in average spending per guest
- Real food cost versus projected food cost
- Satisfaction ratings or online reviews
If more than 10% of guests grumble, you've probably cut too deep.
How do you calculate the optimal portion size when prices rise?
Calculate your current cost per portion
Multiply the old purchase price per kilo by your current portion size in kilos. This is your reference point.
Determine your maximum cost increase
Decide how much euro cost increase per portion is acceptable for your margin. Usually you don't want more than 10-15% increase.
Calculate the new portion size
Divide your maximum cost per portion by the new purchase price per kilo. This gives you the maximum portion size in kilos.
Test customer acceptance
Try the new portion size for 1-2 weeks and monitor customer reactions. Adjust if needed before making the permanent switch.
✨ Pro tip
Track your actual food cost daily for the first 3 weeks after portion adjustments. This catches any kitchen staff still using old measurements and confirms your calculations match reality.
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
How much smaller can portions get before guests start complaining?
Maximum 15-20% reduction at once works safely. For proteins, stick to 10-15% to be extra cautious. If you need bigger cuts, spread them over several months.
Should I reduce portions or just raise menu prices instead?
Depends on your clientele. Budget-conscious diners accept smaller portions better than price hikes. Quality-focused customers often prefer paying more for full portions.
How do I stop my kitchen staff from reverting to old portion sizes?
Update recipes in writing, provide measuring tools, and spot-check regularly. A digital recipe management system keeps everyone aligned and accountable.
Do I need to tell customers about smaller portions?
Generally no, unless changes are dramatic. If questioned, frame it positively as 'refined portions' or 'optimized recipes' rather than admitting cuts.
What's the math for comparing portion reduction versus supplier switching?
Calculate total cost per portion for each option. Compare: (new supplier price × current portion) against (current supplier price × reduced portion). Pick the lower number.
Can I reduce portions on some menu items but not others?
Absolutely. Start with items where guests are less likely to notice - sides, sauces, or dishes with multiple components where one element can shrink without affecting the overall experience.
How do I handle portion reductions for dishes sold by weight?
You can't reduce advertised weights, but you can adjust accompaniments and garnishes. Focus on optimizing the cost of sides, sauces, and non-weighed components instead.
⚠️ 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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