Ordering the right amount each week separates profitable restaurants from struggling ones. Too little stock means disappointed customers and lost revenue. Too much creates waste that drains your cash flow.
Gather your basic data
Smart purchasing calculations require three core elements: standardized recipes with precise portion weights, realistic guest projections for the upcoming week, and buffer stock for unexpected rushes.
💡 Example:
Your bistro serves 350 covers weekly. Steak accounts for 40% of orders:
- 350 covers × 40% = 140 steaks per week
- Per steak: 200 grams of meat
- Total meat needed: 140 × 200g = 28 kg per week
Plus 15% safety margin: 32.2 kg
Calculate ingredient requirements per dish
Work through every menu item systematically. Multiply expected portions by ingredient quantities per serving. This creates your raw purchasing list.
- List every dish you're currently serving
- Estimate what percentage of diners choose each option
- Calculate weekly portion totals per dish
- Multiply by ingredient amounts per serving
⚠️ Note:
Side dishes and garnishes add up fast. That salad served with 60% of entrees? It's probably your third-biggest vegetable expense.
Factor in trim loss and preparation waste
Raw ingredients don't equal servable portions. Whole fish loses 40-50% to bones, heads, and skin. Fresh vegetables typically waste 15-25% during prep. I've seen restaurants underestimate this consistently - a mistake that costs the average restaurant EUR 200-400 per month in unexpected shortages and emergency orders.
💡 Example trim loss:
You need 15 kg of salmon fillet for your dishes. You buy whole salmon:
- Trim loss salmon: 45%
- Yield: 55%
- Purchase needed: 15 kg ÷ 0.55 = 27.3 kg whole salmon
Remember: you divide by the yield, not by the loss!
Build in your safety buffer
Planning exactly what you need guarantees you'll run short. Smart operators add 10-20% extra for walk-ins, delivery delays, and seasonal spikes.
- Slow periods: 10% buffer works fine
- Peak seasons: bump it to 15-20%
- Untested menu items: 25% margin until you know demand
- New supplier relationships: 15% buffer for sizing inconsistencies
Track results and refine weekly
Your initial calculations are educated guesses. Real profitability comes from comparing actual sales against projections each week, then adjusting future orders accordingly.
💡 Example check:
Week 1: You planned 140 steaks, sold 165. Your margin was too tight.
- New percentage: 165 ÷ 350 covers = 47% (was 40%)
- For week 2: 350 × 47% = 165 steaks to plan
- Plus 15% margin: 190 steaks
This way you'll quickly learn the actual proportions.
How do you calculate your weekly purchases? (step by step)
Create an overview of your menu
List all dishes with the exact amounts per ingredient per portion. Estimate the percentage of guests ordering each dish based on your experience or sales data.
Calculate your expected covers
Look at your average number of guests per week from the past month. Account for seasons, events or holiday periods that may affect the number.
Calculate how much you need per ingredient
Multiply covers × percentage that dish is ordered × amount per portion. Add up all dishes that contain the same ingredient.
Add trim loss and safety margin
Divide your net requirement by the yield (100% minus trim loss). Then add 10-20% safety margin for unexpected busy periods.
Check and adjust
Compare your actual sales each week with your plan. Adjust percentages for next week to become increasingly accurate.
✨ Pro tip
Track your portion-to-purchasing ratios for your top 12 revenue-generating dishes over the next 8 weeks. You'll spot ordering patterns that can cut food waste by 15-20% once you nail the calculations.
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 do I know what percentage of my guests order a particular dish?
Pull sales data from your POS system for the last 4-6 weeks. Divide portions sold by total covers served during that period. Starting fresh? Make conservative estimates and adjust weekly based on actual performance.
What if I use ingredients in multiple dishes?
Calculate each dish separately, then add them together. Example: tomatoes in Caesar salad (50g × 80 portions) plus marinara pasta (30g × 120 portions) equals 7.6kg weekly tomato needs.
How much safety margin should I maintain?
Start with 10% during predictable periods. Bump to 15-20% during holidays, events, or unpredictable weather. New menu items need 25% buffers until you understand actual demand patterns.
How do I handle perishable products with short shelf life?
Never order more than 3-4 days of perishables at once. Split your weekly seafood and premium meat orders into 2-3 smaller deliveries to minimize spoilage risk.
What if my supplier doesn't deliver the exact quantities I order?
Set clear minimum and maximum quantities upfront. For variable items like whole fish, confirm exact weights the day before delivery based on your current reservation count.
Should I calculate differently for seasonal menu changes?
Yes - track historical data for seasonal dishes from previous years. New seasonal items need higher safety margins (20-25%) since customer acceptance varies unpredictably.
📚 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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