Your inventory numbers directly control your profit margins. Most restaurant owners track stock levels but never connect those figures to actual profitability. You're leaving money on the table with every dish you serve.
Why inventory and margins are connected
Your inventory costs become your food costs. And food costs determine profit margins. Yet most kitchens operate with disconnected systems: Excel spreadsheets for stock, handwritten recipes, and pure guesswork for actual margins.
💡 Example:
You buy salmon for €18/kg. Your inventory system shows: 5 kg salmon.
- But after filleting you only have 2.8 kg fillet (44% trimming loss)
- Actual fillet price: €18 / 0.56 = €32.14/kg
- If you calculate with €18/kg, you lose €14.14 per kg
At 200 grams per portion, that costs you €2.83 per plate
The four connections you need to make
1. Purchase price to actual cost price
Purchase price isn't your real cost. Trimming waste, spoilage, and inconsistent portions completely change your per-serving costs.
- Trimming loss on fish: 40-55%
- Trimming loss on meat: 15-25%
- Spoilage on vegetables: 10-20%
- Oversized portions: often 20-30% more than calculated
2. Actual cost price to food cost percentage
Once you know true cost per portion, calculate your food cost percentage:
Food cost % = (Cost price per portion / Selling price excl. VAT) × 100
💡 Example:
Steak on your menu: €32.00 (incl. 9% VAT)
- Selling price excl. VAT: €32.00 / 1.09 = €29.36
- Actual cost price of ingredients: €9.20
- Food cost: (€9.20 / €29.36) × 100 = 31.3%
3. Food cost to gross margin
Gross margin shows what remains after ingredient costs:
Gross margin = Selling price excl. VAT - Ingredient costs
In the steak example: €29.36 - €9.20 = €20.16 gross margin per portion.
4. Inventory value to cash flow
Excess inventory ties up cash. Insufficient stock means lost sales opportunities. This is a pattern we see repeatedly in restaurant financials - owners either overstock expensive ingredients or run out during peak service.
⚠️ Watch out:
Many entrepreneurs focus only on purchase prices and ignore trimming losses. Your food costs appear much lower than reality.
Practical connection in 3 steps
Step 1: Measure your actual yields
Weigh what you purchase versus what actually reaches plates:
- Whole fish → fillet weight
- Whole meat → portion weight
- Vegetables → cleaned weight
- Portion size → what actually goes on the plate
Step 2: Calculate actual cost prices
For each main ingredient:
Actual price per kg = Purchase price / (Yield % / 100)
💡 Example:
Whole chicken: €3.20/kg, yield after deboning: 65%
- Actual chicken fillet price: €3.20 / 0.65 = €4.92/kg
- Per portion of 180g: €4.92 × 0.18 = €0.89
Step 3: Link to your selling prices
Verify each dish maintains food costs under 35%. If not, you've got three options:
- Increase selling price
- Reduce portion size
- Source cheaper ingredients
Signs that the connection isn't working
Watch for these red flags:
- Monthly inventory value increases: You're purchasing more than you're selling
- Excessive waste: Portions are oversized or planning is poor
- Food costs above 35%: You're not earning enough per dish
- Cash flow issues despite good revenue: Money is locked in inventory
⚠️ Watch out:
Review supplier pricing monthly minimum. Update cost calculations immediately when prices change, or your food cost accuracy disappears.
Digital vs. manual connection
You can manage this manually through Excel, but it's time-consuming and error-prone. Digital tools automatically connect inventory prices to recipes and calculate real-time food costs per dish.
Benefits of digital systems:
- Automatic recalculation during price changes
- Instant food cost insights per dish
- Alerts for excessive food costs
- Complete inventory value overview
Making the connection matters more than your method. Whether digital or Excel-based, actually tracking these relationships is what counts.
How do you link inventory to margins? (step by step)
Measure your actual yields
For a week, weigh what you buy versus what you actually use. Note the trimming loss per product and the average portion size per dish.
Calculate actual cost prices per portion
Divide your purchase price by the yield percentage. Multiply by your portion size. Add up all ingredients per dish.
Check your food cost percentages
Divide the cost price per portion by your selling price excl. VAT and multiply by 100. Check whether you stay under 35% for profitable dishes.
✨ Pro tip
Track your 3 highest-volume dishes every 2 weeks - if those maintain proper food costs under 32%, you've secured 70% of your profit foundation.
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 often should I update my cost prices?
Monthly minimum, or immediately after supplier price changes. Many suppliers adjust prices without clear notification, so you'll miss cost increases if you're not vigilant.
Should I include all ingredients in the cost price?
Absolutely - every ingredient that touches the plate counts. Oil, butter, spices, garnish, even that pinch of salt adds up over hundreds of servings.
What if my food cost comes out above 35%?
You're likely losing money on that dish. Raise the selling price, trim portion sizes, or source cheaper ingredients. Don't ignore dishes bleeding profit.
How do I prevent my inventory from getting too high?
Monitor inventory value weekly. Rising values every week means you're buying more than selling. Base purchases on projected sales, not gut feelings.
Can I do this with Excel instead of specialized software?
Yes, but expect significant time investment and error potential. Every price change requires manual adjustments across multiple calculations. Digital tools automate these updates instantly.
What's the biggest mistake restaurants make with inventory-margin connections?
Ignoring trimming losses and yield percentages completely. They calculate margins using purchase prices instead of actual usable ingredient costs, creating phantom profits that don't exist.
📚 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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