Food waste costs restaurants an average of 3-5% of their revenue, but most owners can't pinpoint which products drain their profits. Picture this: you're throwing away what could be your monthly equipment payment without even realizing it. Systematic tracking reveals exactly which ingredients deserve your immediate attention.
Why measuring waste is so important
Waste sneaks up on you. A wilted bunch of herbs here, some day-old fish there — seems insignificant, but it accumulates fast. Most kitchens waste between 5% and 15% of their purchases. With annual revenue of €400,000, that's €6,000 to €18,000 literally going in the trash.
💡 Example:
Restaurant De Kroon tracks all waste for one week:
- Fish: €45 discarded (poor planning)
- Lettuce: €12 discarded (over-ordered)
- Bread: €8 discarded (past expiration)
- Meat: €3 discarded (spoilage)
Total: €68 per week = €3,536 per year in waste alone
The three types of waste in your kitchen
Not all waste happens for the same reasons. There are three main causes, each requiring a different fix:
- Purchasing waste: Over-ordered, products past expiration
- Preparation waste: Mise-en-place that doesn't get used, incorrectly prepared items
- Plate waste: What guests leave behind (portions too large, taste issues)
Each type demands a different solution. That's why you need to know exactly where your waste originates.
How to calculate waste per product
The formula for waste percentage per product is straightforward:
Waste % = (Discarded weight / Purchased weight) × 100
💡 Example calculation:
You buy 10 kg of salmon every week for €180:
- Week 1: 1.2 kg discarded
- Week 2: 0.8 kg discarded
- Week 3: 1.5 kg discarded
- Week 4: 0.9 kg discarded
Average: 1.1 kg per week = (1.1 / 10) × 100 = 11% waste
Cost: 11% of €180 = €19.80 per week = €1,030 per year
What figures you need to track
For accurate analysis, you need this data per product:
- Purchased weight per week (in kg or units)
- Discarded weight per day (weigh before disposal)
- Reason for discarding (expired, spoiled, over-prepared)
- Purchase price per kg (to calculate financial impact)
⚠️ Note:
Track for at least 4 weeks to get reliable averages. One problematic week skews your actual waste picture.
Identifying the biggest waste makers
From tracking this across dozens of restaurants, I've found you should rank products in two ways:
1. Highest waste percentage:
Which product do you waste most relatively? This reveals where your processes fail worst.
2. Highest absolute costs:
Which product costs you most money through waste? This shows where you'll make the biggest savings.
💡 Example ranking:
Highest waste percentage:
- Lettuce: 25% (€3/week)
- Fish: 11% (€20/week)
- Meat: 4% (€8/week)
Highest absolute costs:
- Fish: €20/week
- Meat: €8/week
- Lettuce: €3/week
Focus first on fish (biggest impact) then on lettuce (easiest to fix).
What to do with the numbers
Once you know which products are your biggest waste makers, take targeted action:
- High waste + high costs: Priority 1 — adjust purchasing or preparation immediately
- High waste + low costs: Easy wins — often simple to fix
- Low waste + high costs: Monitor closely — small increases have big impact
Most restaurants can reduce waste by 30-50% by tackling their top 3 waste makers.
How do you calculate waste per product? (step by step)
Measure all waste for 4 weeks
Place a scale by the trash bin and weigh everything you throw away per product. Also note the reason: past date, spoilage, over-prepared, or what guests left behind.
Calculate the waste percentage per product
Divide the discarded weight by the purchased weight and multiply by 100. For example: 1.1 kg discarded from 10 kg purchased = (1.1/10) × 100 = 11% waste.
Rank by percentage and absolute costs
Make two lists: which product has the highest waste percentage, and which product costs you the most money through waste. Focus first on products that score high on both lists.
✨ Pro tip
Track your top 5 most expensive ingredients for exactly 2 weeks during your busiest period. These premium items often account for 60-70% of your total waste costs, making them your fastest path to savings.
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
Do I really need to weigh everything I throw away?
For accurate analysis, absolutely. Estimating gives a distorted picture. After 4 weeks you'll know exactly where your money's leaking and can take targeted action.
What's a normal amount of waste?
Most restaurants waste 5-15% of their purchases. Below 5% is excellent, above 15% really costs you money. Fresh products like fish and vegetables often have higher waste percentages.
How do I prevent my team from forgetting to weigh?
Make it part of the closing routine. Assign one person responsibility and explain why it matters. Once your team sees how much money gets thrown away, they often cooperate better.
Should I count trimming loss as waste?
No, trimming loss is normal and part of the cost price. Only count what's truly discarded: spoilage, expired items, over-prepared food, or what guests leave behind.
Can I automate this with an app?
Partially. Apps can help track figures and calculations, but your team still needs to manually weigh and record waste data.
How often should I recalculate waste percentages after making changes?
Recalculate every 6-8 weeks once you've implemented changes. This gives enough time to see if your adjustments are working without constantly shifting your approach.
What if my waste percentages vary dramatically between seasons?
That's normal for seasonal ingredients. Track waste separately for high and low seasons, then adjust your purchasing patterns accordingly. Summer vegetables will always waste differently than winter root vegetables.
📚 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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