Accurate sales forecasting cuts waste percentages by 60-70% within eight weeks. Most restaurants discard 10-15% of purchases due to poor guest predictions. Precise forecasting transforms ordering accuracy and slashes unnecessary waste.
What's the connection between forecasting and waste?
Waste happens when you order too much for actual guest counts. A restaurant expecting 100 covers but serving 80 has over-ordered fresh products by 20%. Those extras typically land in the dumpster.
💡 Example:
Restaurant expects 120 covers on Saturday:
- Salmon ordered: 15 kg at €18/kg = €270
- Actual number of guests: 90 covers
- Salmon used: 11.25 kg
- Salmon thrown away: 3.75 kg = €67.50
Waste percentage: 25% of salmon purchase
Calculate your current waste percentage
Before improving forecasts, establish your baseline. Track discarded items for seven days and compare against purchases.
Waste percentage formula:
Waste % = (Thrown away in kg / Purchased in kg) × 100
💡 Example calculation:
Week 1 figures:
- Vegetables purchased: 50 kg
- Vegetables thrown away: 7.5 kg
- Fish purchased: 25 kg
- Fish thrown away: 3 kg
Vegetable waste: (7.5 / 50) × 100 = 15%
Fish waste: (3 / 25) × 100 = 12%
Measure your forecast accuracy
Solid sales forecasts stay within 10% of reality. Calculate your deviation by comparing expected covers against actual covers.
Forecast accuracy formula:
Deviation % = |Expected - Actual| / Actual × 100
⚠️ Note:
Use the absolute value (|...|) so that both overestimates and underestimates count as deviations.
Calculate the impact of improvement
Better forecast accuracy enables precise ordering. This directly reduces your waste percentage. Something most kitchen managers discover too late is that even a 5% improvement in forecast accuracy can cut waste costs by 40%.
💡 Scenario comparison:
Current situation:
- Forecast deviation: 25%
- Waste percentage: 15%
- Weekly purchases: €2,000
- Waste per week: €300
After forecast improvement:
- Forecast deviation: 10%
- Expected waste percentage: 6%
- Waste per week: €120
- Savings: €180 per week = €9,360 per year
Factors that improve your forecast
Better forecasting requires pattern tracking. Analyze historical data and external factors affecting occupancy rates.
- Seasonal patterns: Summer vs winter, school holidays
- Weekly patterns: Which days are always busy/quiet
- Weather impact: Rain, sun, temperature
- Local events: Festivals, sports matches, holidays
- Reservations: How many walk-ins come on top
Calculate the financial impact
Waste costs exceed purchase prices due to labor, energy, and storage expenses. Calculate using 1.3× the purchase price as actual waste costs.
Total waste costs = Thrown away amount × 1.3
💡 Annual impact calculation:
Restaurant with €8,000 monthly purchases:
- Current waste: 12% = €960/month
- Actual costs: €960 × 1.3 = €1,248/month
- After better forecast: 5% = €400/month
- Actual costs: €400 × 1.3 = €520/month
Annual savings: (€1,248 - €520) × 12 = €8,736
Practical tools for better forecasts
Begin with simple tracking methods. A spreadsheet recording daily covers, weather, and notes provides valuable insights. Analyze patterns across at least three months.
Food cost calculators like KitchenNmbrs help track purchases and waste, making it easier to identify which improvements impact your numbers.
How do you calculate the effect of better forecasting? (step by step)
Measure your current waste percentage
Track what you throw away per product category for a week. Divide this by your total purchases and multiply by 100 for the percentage. Do this for at least 4 weeks to get a reliable average.
Calculate your forecast accuracy
Compare your expected number of covers with your actual covers per day. Calculate the difference in percentages: |Expected - Actual| / Actual × 100. A deviation above 15% means lots of room for improvement.
Set a realistic improvement goal
Cut your current forecast deviation in half as a first goal. If you're currently off by 20%, aim for 10%. This usually gives a waste reduction of 30-50%. Calculate the financial impact: current waste × reduction factor × 1.3 (for total costs).
✨ Pro tip
Track your top 3 most expensive proteins for exactly 14 days, measuring both forecast deviation and waste percentage daily. This focused approach delivers maximum financial impact while requiring minimal paperwork overhead.
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's a realistic waste percentage to aim for?
For fresh products, 3-6% waste is achievable. Restaurants with accurate forecasting often reach 5% or lower. Anything above 10% signals you need better forecasting or purchasing strategies.
How long does it take to see results from better forecasting?
You'll notice waste percentage improvements within 2-3 weeks. However, developing stable patterns and significantly improving forecasts requires 2-3 months of consistent tracking.
Do I need to track waste separately for each product?
Focus first on your most expensive and perishable items: fish, meat, and fresh vegetables. These create the biggest impact on waste costs. Add bread and shelf-stable products once you've mastered the high-value items.
What if my waste mainly comes from preparation, not from wrong forecasts?
Then your issue is portioning or kitchen processes, not purchasing. Separate pre-preparation waste (spoiled/expired) from post-preparation waste (failed dishes/leftovers) to identify the real problem.
Can I completely prevent waste with a perfect forecast?
No, some waste always exists due to spoilage, seasonal changes, and unexpected events. Even excellent forecasting leaves 3-5% waste as normal and unavoidable.
Should I adjust ordering quantities immediately after one bad forecast day?
Never make ordering changes based on single-day results. Track patterns over 7-14 days minimum before adjusting quantities, as one-off events can skew your data significantly.
How do walk-in customers affect my forecast accuracy calculations?
Track your walk-in percentage separately from reservations for 30 days. Most restaurants see 15-40% walk-ins with predictable patterns by day of week and season.
📚 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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