Here's what most kitchen managers discover too late: that amazing supplier deal turned into expensive waste because they skipped the break-even math. You need to know exactly how much you must sell to recoup your investment before anything spoils.
Calculate your break-even point on offers
Every offer requires answering two questions: how much do I save per portion? and how much extra do I need to sell to recoup the investment?
? Example:
Your supplier offers salmon at €18/kg (normally €24/kg). You must buy a minimum of 20 kg.
- Savings: €6/kg
- Total investment: 20 kg × €18 = €360
- Your salmon dish normally has €6 food cost, now €4.50
- Extra profit per portion: €1.50
Break-even: €360 ÷ €1.50 = 240 portions
Estimate your sales speed realistically
The critical question: will you sell those 240 portions before the salmon spoils? Salmon lasts 3-4 days. If you typically sell 30 salmon daily, you'll barely make it. But what about slow weeks?
- Review your sales data: how much of this product did you move last month?
- Divide by working days for daily average
- Reduce by 20% for slower periods
- Multiply by shelf life days
⚠️ Note:
Always use your weakest sales figures from the past 3 months. Never your strongest week.
Factor spoilage risk into your decision
If you're tossing 20% of your bulk purchase, you're actually paying more than regular prices. Calculate your maximum allowable spoilage percentage:
? Maximum spoilage calculation:
Salmon example: €6/kg savings on €18/kg purchase price
- Savings percentage: €6 ÷ €18 = 33%
- You can waste a maximum of 33%
- More than 33% = costlier than regular purchasing
Safe buffer: allow 10% cushion → max 23% spoilage
Alternatives for large offers
Big batches can often be split or repurposed:
- Freeze: portion immediately and freeze
- Process: create a daily special or weekly menu feature
- Collaborate: split the batch with another restaurant
- Adjust menu: temporarily highlight the product more prominently
Seasonal products require a different approach
With seasonal items like asparagus, oysters or game, it's often: buy now or wait a year. Here you calculate differently. Most kitchen managers discover too late that seasonal timing completely changes the risk equation - even high spoilage rates can still beat waiting for next season's prices.
? Seasonal example:
White asparagus in week 3 of season: €8/kg (end of season: €15/kg)
- Normal food cost asparagus dish: 35%
- With discounted asparagus: 28%
- 7 percentage point difference = €2.80 extra profit per €40 dish
Even with 30% spoilage you still profit
Make agreements about flexibility
Always negotiate terms on large batches:
- Staggered delivery: 20 kg over 2 weeks instead of one shipment
- Return rights: return unsold portion at cost price
- Exchange guarantee: swap surplus for different products
- Payment delay: pay only after sale
⚠️ Note:
Document agreements in writing. Even with trusted suppliers. WhatsApp messages count as proof too.
Related articles
How do you assess an offer? (step by step)
Calculate savings per portion
Subtract offer price from normal purchase price. Convert to cost difference per dish. This is your extra profit per sold portion.
Determine break-even quantity
Divide total investment by extra profit per portion. This is the number of portions you need to sell to make the offer profitable.
Check realistic sales
Look at your sales figures from last month. Divide by working days and subtract 20% for safety. Can you reach the break-even quantity within the shelf life?
Calculate maximum spoilage
Divide savings amount by offer price. This is the maximum percentage you can throw away before you're more expensive than normal purchase.
Make the decision
If your expected sales are higher than break-even and spoilage risk stays below the limit, the offer is attractive. Otherwise not.
✨ Pro tip
Track every bulk purchase over the next 8 weeks: quantity bought, portions sold, waste percentage. You'll spot your actual sales patterns and make smarter decisions.
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 I don't know my sales figures exactly?
Can I always freeze surplus stock?
What is a safe spoilage margin to allow for?
How do I handle seasonal products that get more expensive later?
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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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