Linking your purchasing plan to reservation numbers can reduce food waste by 15-30%. Many restaurants buy based on gut feeling, which leads to overbuying on slow days and underbuying on busy days. By connecting your purchases to expected guest flow, you prevent waste and shortages.
Why use reservation numbers for purchasing?
Your reservation system contains a goldmine of data. It tells you not only how many guests are coming, but also when they're coming and what they're likely to order. You can turn this information into concrete savings.
💡 Example:
Restaurant with 60 covers on Tuesday vs. 120 on Friday:
- Tuesday: 60 guests × 30% order fish = 18 fish dishes
- Friday: 120 guests × 30% order fish = 36 fish dishes
- Without planning: buy 40 portions of fish every day
- With planning: Tuesday 20 portions, Friday 40 portions
Savings: 2 portions of fish per Tuesday = €24 per week
The basic calculation: from reservations to purchasing
The formula is simple, but execution requires some data analysis. You need three numbers: expected guests, average order per dish, and safety stock.
Basic formula:
Required quantity = (Expected guests × Dish popularity %) + Safety stock %
💡 Example calculation:
Saturday: 100 reservations expected
- Steak: 100 × 25% = 25 portions + 10% buffer = 28 portions
- Salmon: 100 × 20% = 20 portions + 10% buffer = 22 portions
- Pasta: 100 × 35% = 35 portions + 5% buffer = 37 portions
Without planning you might buy 30-30-40 = 5 portions too many
Using historical data for accuracy
The key is analyzing your sales data by day of the week. Monday has a different ordering profile than Friday. Guests order different dishes in winter than in summer.
- Analyze at least 3 months of sales data per weekday
- Calculate average popularity per dish per day
- Pay attention to seasonal influences (summer: more salads, winter: more stews)
- Account for special events and holidays
⚠️ Note:
Walk-ins can disrupt your planning. Keep at least 10-15% buffer for unexpected guests, especially on popular days.
Calculating the financial impact
To measure savings, compare your old purchasing pattern with your new, data-driven approach. The savings come from less waste of perishable products.
💡 Savings calculation:
Restaurant with €8,000 weekly purchasing:
- Old waste: 12% = €960 per week
- New waste with planning: 7% = €560 per week
- Savings: €400 per week = €20,800 per year
ROI of better planning: €20,800 per year
Practical tools and systems
You can do this manually with Excel, but digital tools make it much easier. Some POS systems can export sales data, which you can link to your reservation system.
- Export your sales data weekly from your POS system
- Use your reservation system to forecast future guest flow
- Create a simple Excel sheet combining both datasets
- Apps like KitchenNmbrs can help track recipe popularity
Common mistakes in purchasing planning
Most restaurants make the same thinking mistakes when planning their purchases. By recognizing these, you avoid costly errors.
- Focusing too much on yesterday: Tuesday was busy, so buy a lot on Wednesday too
- Ignoring seasons: Using December patterns for March planning
- No buffer for popular dishes: If your steak sells out, you lose revenue
- Not considering storage space: You can't keep everything fresh
⚠️ Note:
Start small. Test your new purchasing plan first on 2-3 main dishes before overhauling your entire menu. This way you learn the system without major risks.
How do you calculate the savings? (step by step)
Gather your current waste data
Measure for 4 weeks how much you throw away per product category. Note this as a percentage of your purchases. On average, restaurants waste 8-15% of their fresh products.
Analyze your sales patterns by weekday
Export 3 months of sales data from your POS system. Calculate per weekday what percentage of your guests order which dish. Monday has different patterns than Saturday.
Create your purchasing formula and test for 2 weeks
Use the formula: (Expected guests × Popularity %) + 10% buffer. Test this on your 3 most popular dishes and measure whether your waste decreases without creating shortages.
✨ Pro tip
Start by planning your most expensive ingredients first. A 20% better plan for your meat and fish yields more than perfect planning of your vegetables.
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
How much buffer should I keep for unexpected guests?
For perishable products 10-15%, for non-perishable products 5-10%. Keep a slightly larger buffer on Friday and Saturday because walk-ins are more common then.
What if my POS system doesn't provide detailed sales data?
Start by manually counting your 5 most popular dishes for 2 weeks. That already gives you 70-80% of your sales pattern and is enough to get started.
How do I handle seasonal influences in my planning?
Create separate calculations for summer and winter. Salads and cold dishes are more popular in warm months, stews and soups in cold months.
Can I use this system for beverages too?
Yes, but beverages have less waste because they last longer. Focus first on fresh products like fish, meat, and vegetables where the savings are greatest.
What if I get a lot of last-minute reservations?
Account for your average last-minute increase. If you normally get 20% extra reservations on the day itself, build that into your planning.
📚 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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