Most restaurant owners assume all food waste happens in the kitchen, but that's wrong. Your biggest losses might actually come from poor purchasing decisions or oversized portions that guests can't finish. Pinpointing the exact source determines which fix will save you the most money.
The three sources of waste
Waste hits your bottom line at three critical points. Each demands a completely different approach:
- Purchasing: Over-ordered, wrong products, poor quality
- Preparation: Mise-en-place that doesn't work out, cutting loss, overcooking
- Portion size: Overfilled plates, guests leaving food uneaten
Step 1: Measure your total waste
Run a seven-day tracking period. Weigh every item you discard and document exactly why it's going in the trash:
💡 Example measurement week:
Restaurant with €3,000 in purchases per week:
- Purchasing waste: €180 (6%)
- Kitchen waste: €120 (4%)
- Plate returns: €90 (3%)
Total waste: €390 = 13% of purchases
Step 2: Analyze purchasing waste
Purchasing waste is anything that goes directly from storage to trash:
- Spoiled vegetables/meat from extended storage
- Products beyond expiration dates
- Over-ordered for cancelled events
- Incorrect products delivered
⚠️ Watch out:
When more than 8% of purchases get discarded unused, your ordering system or storage methods need immediate attention.
Step 3: Check preparation waste
Prep waste happens during the cooking process:
- Mise-en-place that doesn't sell (over-prepped)
- Excessive cutting loss beyond normal trimming
- Ruined dishes (burnt, overseasoned, etc.)
- Unused sauces and garnish components
💡 Example preparation check:
You buy 10 kg of potatoes for €8:
- Standard cutting loss: 15% = 1.5 kg
- Your actual loss: 2.8 kg = 28%
- Excess waste: 1.3 kg = €1.04
Root cause: inefficient peeling technique or subpar potato quality.
Step 4: Analyze plate returns
Portion waste shows up in what customers leave behind:
- Large protein portions left unfinished
- Untouched side dishes and garnishes
- Unpopular sauce selections
- Oversized servings customers can't complete
Track this by monitoring plate waste during bussing for seven consecutive days. From analyzing actual purchasing data across different restaurant types, if more than 20% of diners consistently abandon food, you're serving excessive portions.
The costs per type of waste
Different waste sources impact your margins differently:
💡 Cost example:
Restaurant with €150,000 annual revenue:
- Purchasing waste (6%): €2,700/year
- Preparation waste (4%): €1,800/year
- Portion waste (3%): €1,350/year
Total: €5,850/year = nearly €500/month
Determine priority
Tackle your largest waste category first:
- Purchasing > 8%: Overhaul purchasing planning and FIFO protocols
- Preparation > 6%: Retrain kitchen staff on portioning and prep techniques
- Plate returns > 4%: Reduce portion sizes strategically
Using tools like KitchenNmbrs helps you track ingredient costs per dish, revealing which specific waste categories drain your profits most severely.
How do you determine the source of waste? (step by step)
Measure all waste for one week
Weigh everything that gets thrown away and note the reason: spoiled, past date, failed dish, or plate return. Divide this into three categories: purchasing, preparation, and portion waste.
Calculate the percentage per category
Divide each category by your total purchases for that week and multiply by 100. Purchasing waste above 8%, preparation above 6%, or plate returns above 4% require action.
Address the biggest cost item first
Focus on the category with the highest percentage. For purchasing problems: improve planning and storage. For preparation: train portioning. For plate returns: reduce portions or adjust recipes.
✨ Pro tip
Track waste during the same week each month for 3 consecutive months to establish reliable patterns. Busy holiday weeks skew your data compared to typical service periods, so consistency in timing reveals true waste trends.
Calculate this yourself?
In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.
Was this article helpful?
Frequently asked questions
Should I count cutting loss as waste?
Normal cutting loss (peels, bones) isn't waste—it's expected processing loss. Only count it as waste when your cutting loss exceeds standard percentages, like fish yielding 35% instead of the typical 45%. Track that difference as actual waste.
How do I know if my portions are too large?
Monitor plate returns during bussing for one full week. If more than 20% of customers consistently leave substantial food uneaten, your portions exceed what most diners can finish.
What if my waste mainly comes from one dish?
Focus your analysis on that specific menu item. Check if portions are oversized, flavors need adjustment, or preparation consistency varies between cooks. Sometimes removing a problematic dish saves more money than trying to fix it.
📚 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.
Make better decisions with real numbers
Should you change your menu? Raise prices? Test a new concept? KitchenNmbrs simulates scenarios with your own data. Try it free for 14 days.
Start free trial →