Picture this: you bid on premium Dover sole expecting to pay €24/kg, but walk away at €32/kg – suddenly your carefully planned 30% food cost jumps to 40%. Most restaurants buying through auctions face this margin squeeze regularly. The key isn't avoiding auctions, but calculating smarter.
Why auction purchasing destroys margins
Auction prices swing based on supply, weather, and how many buyers show up that day. You might pay €18/kg one Tuesday and €35/kg the next. This volatility makes traditional margin calculations useless.
⚠️ Watch out:
Most restaurants calculate with average purchase prices, then get blindsided when auction prices spike 40% above expectations.
Calculate margins with wild price swings
Forget fixed pricing – auction products need range-based calculations. You're managing risk, not just costs.
💡 Example: Dover sole from fish auction
Menu price: €42.00 incl. VAT (€38.53 excl.)
- Best-case auction price: €18/kg
- Typical price: €24/kg
- Worst-case price: €32/kg
- Portion size: 200 grams
At €32/kg: €6.40 per portion = 16.6% food cost
At €24/kg: €4.80 per portion = 12.5% food cost
Three bulletproof margin strategies
1. Dynamic daily pricing
Match your menu price to that day's auction results. Daily specials work perfectly for this approach.
- Check morning auction prices
- Calculate minimum selling price for target margin
- Update daily menu boards
2. Average price plus safety buffer
Build in a 20% cushion above average prices to absorb those expensive days. Something most kitchen managers discover too late: this buffer saves you from constantly repricing dishes.
💡 Example calculation:
Typical auction price: €24/kg
Plus 20% buffer: €28.80/kg
200g portion cost: €5.76
Minimum selling price at 30% food cost: €19.20 excl. VAT
3. Set hard spending limits
Agree on maximum prices with your auction house. Walk away if bidding goes higher – protecting margins beats having the dish available.
Factor in processing waste
Auction products usually arrive whole or unprocessed. Your real cost per usable portion is much higher than the auction price suggests.
💡 Example: Whole fish breakdown
Auction price: €20/kg whole
Processing waste: 45% (head, bones, skin)
Usable yield: 55%
True fillet cost: €20 ÷ 0.55 = €36.36/kg
Track everything religiously
Document these details for every auction purchase:
- Purchase date and auction price per kg
- Total weight and actual yield after processing
- Menu prices charged that day
- Final food cost percentage achieved
Systems like KitchenNmbrs can track daily auction prices and automatically recalculate your food costs based on actual purchase data.
⚠️ Watch out:
Auction prices can swing 50% in a single week. Monitor your margins at least twice weekly to catch problems early.
Don't assume auctions save money
Calculate the total cost including your time and labor:
- Extra prep time for whole products
- Higher waste from inconsistent quality
- Menu uncertainty from supply gaps
- Additional labor for processing
If your true cost (auction price + processing time) exceeds fixed supplier pricing, you're losing money chasing quality.
How do you calculate margin with auction purchasing? (step by step)
Collect price data from at least 4 weeks
Record all auction prices for your product over a month. Calculate the lowest, average, and highest price. This gives you a realistic price range.
Calculate actual cost price including trim loss
Divide the average auction price by the yield percentage after processing. At 45% trim loss you divide by 0.55. This is your actual cost price per kg of usable product.
Determine your minimum selling price with buffer
Take the actual cost price plus 20% buffer for outliers. Divide this by your desired food cost percentage. This gives you minimum selling price excl. VAT.
Monitor and adjust weekly
Check your actual purchase prices against your calculation every week. Adjust your menu price if the auction price structurally runs higher or lower than expected.
✨ Pro tip
Only auction-buy products you'll sell 150+ portions weekly. Below that volume, the 2-3 hours of extra processing and admin time costs more than any savings you'll achieve.
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
Should I adjust menu prices daily based on auction results?
Only for daily specials or when prices spike 30%+ above your buffer. For regular menu items, use average pricing with a 20% safety margin to avoid constant repricing.
How do I avoid overpaying at auctions?
Calculate your maximum bid price before arriving, based on your target food cost percentage. Never exceed it, regardless of product quality. Better to skip a day than kill your margins.
What's my backup plan when auction prices exceed my budget?
Always maintain relationships with fixed-price suppliers for emergency sourcing. Or design flexible menus where you can substitute auction items with profitable alternatives.
How do I handle the extra admin work from fluctuating prices?
Record actual purchase prices daily and update recipe costs immediately. Food cost software can automate these calculations and show real-time margin impacts.
⚠️ 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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