Supplier offers can significantly improve your margin, but also lead to waste if you miscalculate. The secret is in the break-even calculation: how much do you need to sell to break even? In this article you'll learn step-by-step how to calculate every offer for profitability versus spoilage risk.
Calculate your break-even point on offers
For every offer you need to answer 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 crucial question: will you sell those 240 portions before the salmon spoils? Salmon keeps for 3-4 days. If you normally sell 30 salmon per day, you'll just make it. But what if it's quiet weeks?
- Check your sales figures: how much did you sell of this product last month?
- Divide by working days for average per day
- Subtract 20% for quiet periods
- Multiply by shelf life days
⚠️ Note:
Always calculate with your lowest sales figures from the past 3 months. Not with your best week.
Factor spoilage risk into your decision
If you have to throw away 20% of your offer, you're still worse off than the normal purchase price. Therefore calculate your maximum spoilage percentage:
💡 Maximum spoilage calculation:
Salmon example: €6/kg savings on €18/kg purchase price
- Savings percentage: €6 ÷ €18 = 33%
- You can throw away a maximum of 33%
- More than 33% = more expensive than normal purchase
Safe margin: allow 10% extra → max 23% spoilage
Alternatives for large offers
Large batches can often be split or used differently:
- Freeze: portion immediately and freeze
- Process: make it a daily special or weekly menu item
- Collaborate: share the batch with a colleague restaurant
- Adjust menu: feature the product more prominently on the menu temporarily
Seasonal products require a different approach
With seasonal products like asparagus, oysters or game, the choice is often: buy now or wait a year. Here you weigh things differently:
💡 Seasonal example:
White asparagus in week 3 of the season: €8/kg (end of season: €15/kg)
- Normal food cost asparagus dish: 35%
- With cheap asparagus: 28%
- 7 percentage point difference = €2.80 extra profit per €40 dish
Even with 30% spoilage you come out ahead
Make agreements about flexibility
Always try to negotiate on large batches:
- Staggered delivery: 20 kg over 2 weeks instead of all at once
- Return rights: bring back unsold portion at cost price
- Exchange guarantee: exchange surplus for another product
- Payment delay: pay only after sale
⚠️ Note:
Put agreements in writing. Even with suppliers you know well. WhatsApp messages also count as proof.
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
Keep a log of offers: what you bought, how much you sold, how much was wasted? After a few months you'll know your own sales patterns much better.
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?
Estimate conservatively. Check your cash register system or count how many portions you normally make per day. When in doubt: calculate with 30% less than your estimate.
Can I always freeze surplus stock?
Not all products freeze well. Fish and meat usually do, vegetables and dairy often don't. Always check quality after thawing before freezing large batches.
How do I negotiate flexible delivery terms?
Start by asking: 'Can it also be delivered in two shipments?' or 'What if I don't sell everything?' Many suppliers are more flexible than they initially appear, especially with good customers.
What is a safe spoilage margin to allow for?
Stay at least 10 percentage points below your maximum spoilage percentage. If you can throw away a maximum of 30%, plan for a maximum of 20% spoilage.
Should I include VAT in these calculations?
No, always calculate excl. VAT. Both your purchase prices and sales prices are then comparable. You pay VAT to the tax authority anyway.
How do I handle seasonal products that get more expensive later?
With seasonal products you weigh current price against expected price later in the season. Even with some spoilage you can often come out ahead compared to buying later.
📚 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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