Leftovers and waste make food cost calculation tricky. You buy ingredients for 100 portions, but only sell 80. How do you calculate your actual food...
Leftovers and waste make food cost calculation tricky. You buy ingredients for 100 portions, but only sell 80. Your actual cost per portion jumps higher than expected.
Why leftovers disrupt your food cost
Your food cost formula is straightforward: (Ingredient costs / Sales price excl. VAT) × 100. But what happens if you buy ingredients for 100 portions and only sell 80? Your actual costs per portion shoot up beyond what you calculated.
💡 Example:
You buy ingredients for risotto for 100 portions:
- Arborio rice: €25
- Parmesan: €18
- Vegetables: €12
- Other ingredients: €15
Total: €70 for 100 portions = €0.70 per portion
But you only sell 75. Then each sold portion costs: €70 / 75 = €0.93
Your food cost is 33% higher than calculated!
The actual food cost formula with leftovers
With leftovers, you need this adjusted formula:
Actual food cost = (Total ingredient costs / Number of sold portions) / Sales price excl. VAT × 100
Notice the difference: you divide by the number of sold portions, not the number of made portions.
⚠️ Watch out:
Many entrepreneurs calculate using the number of made portions. This makes your food cost look lower than it actually is. Always calculate with sold portions if there are leftovers.
Different types of 'leftovers'
Not all leftovers are the same. You've got different categories:
- Perishable leftovers: Fresh fish, meat, lettuce that you toss out
- Shelf-stable leftovers: Rice, pasta, frozen items you can use tomorrow
- Reusable leftovers: Vegetable scraps for soup, meat for ragout
- Trim loss: Peels, bones, unusable parts
For your food cost calculation, everything you've purchased counts, even if you reuse it later.
💡 Practical example:
Monday you buy €200 worth of ingredients for 80 portions of pasta. You sell 65.
Tuesday you use the leftovers for 10 new portions, without additional purchases.
Total sold: 75 portions for €200 purchase = €2.67 per portion in ingredients.
Not €200 / 80 = €2.50 per portion!
How to calculate your waste percentage
To get control of leftovers, calculate your waste percentage:
Waste % = (Value thrown away / Total purchase value) × 100
A typical waste percentage in restaurants runs between 4% and 10%. Above 10% you're hemorrhaging money.
💡 Calculation example:
This week you purchased €1,200 worth of ingredients. You threw away €85 worth.
Waste: (€85 / €1,200) × 100 = 7.1%
That's acceptable. Above 10% you need to take action.
Practical tips to minimize leftovers
Fewer leftovers means better food cost. Here are practical methods:
- Buy smaller quantities: Rather 3× per week fresh than 1× large batch
- Apply FIFO: First In, First Out - use oldest products first
- Reuse leftovers: Vegetable scraps for soup, meat for ragout
- Standardize portions: Fixed grams per portion, not 'by feel'
- Count daily: What's left? What needs to be used?
The impact of leftovers on your annual revenue
From tracking this across dozens of restaurants, leftovers cost more than you think. An example:
⚠️ Calculation example:
You throw away an average of €15 per day in perishable products. That seems little, but: €15 × 6 days × 52 weeks = €4,680 per year. With an average food cost of 30% you lose €15,600 in potential revenue.
Digital help with tracking
Manually tracking leftovers and waste takes time. Many entrepreneurs use food cost calculators to calculate this automatically. You enter what you've purchased and sold, and the system calculates your actual food cost including waste.
This gives you insight into which products often remain, so you can adjust your purchases.
How do you calculate food cost with leftovers? (step by step)
Add up all ingredient costs
Note everything you've purchased for this dish, including oil, spices and garnish. Even if you haven't used it all. These are your total ingredient costs.
Count the number of sold portions
Not the number you've made, but the number you've actually sold. Leftovers don't count, even if you use them later.
Calculate costs per sold portion
Divide your total ingredient costs by the number of sold portions. This gives you the actual ingredient costs per portion, including waste.
Calculate your actual food cost percentage
Divide the cost per portion by your sales price excluding VAT and multiply by 100. This is your actual food cost including leftovers.
✨ Pro tip
Track your waste for exactly 14 days to identify patterns - you'll discover which ingredients consistently get wasted and can adjust your ordering by 20-30% on those items. Most restaurants see immediate cost improvements within the first month.
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 count reusable leftovers in my food cost?
Yes, everything you've purchased counts, even if you use it later. The costs have been incurred, regardless of timing. This prevents you from underestimating your true ingredient costs.
What is a normal waste percentage?
Between 4% and 10% of your purchase value is typical. Above 10% you're losing too much money and need to adjust your purchases or portioning.
Should I calculate trim loss differently than leftovers?
Trim loss is predictable and you calculate it in advance in your cost price. Leftovers are unpredictable and you calculate them afterwards in your actual food cost. They require different tracking methods.
📚 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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