The Formulas That Run Your Kitchen
Food cost is the single biggest controllable expense in a restaurant. These formulas help you understand where your money goes, where it's leaking, and what to fix.
1. Food Cost Percentage
The most important number in your kitchen.
Food Cost % = (Cost of Goods Sold ÷ Food Revenue) × 100
Example: You spent $8,500 on food this week and sold $28,000 in food. $8,500 ÷ $28,000 = 30.4%
Target: 28–35% (varies by concept — fine dining is higher, fast casual is lower)
2. Cost of Goods Sold (COGS)
COGS = Beginning Inventory + Purchases − Ending Inventory
Example:
- Starting inventory Monday: $12,000
- Purchases this week: $8,500
- Ending inventory Sunday: $11,000
- COGS = $12,000 + $8,500 − $11,000 = $9,500
3. Plate Cost
What it actually costs to make one serving of a dish.
Plate Cost = Sum of all ingredient costs for one portion
Example (Grilled Salmon):
- Salmon fillet (8oz): $4.50
- Risotto (6oz): $0.90
- Asparagus (4 spears): $0.60
- Butter, oil, seasoning: $0.30
- Total plate cost: $6.30
4. Menu Price from Target Food Cost
Menu Price = Plate Cost ÷ Target Food Cost %
Example: Your salmon costs $6.30 to plate and you target 30% food cost. $6.30 ÷ 0.30 = $21.00 menu price
5. Actual vs. Theoretical Food Cost
Theoretical food cost = what your food cost should be based on recipes and POS sales Actual food cost = what it actually was based on inventory
Variance = Actual − Theoretical
If theoretical says 29% but actual is 33%, that 4% gap is waste, theft, portioning errors, or unrecorded usage. Every 1% of food cost on $1M in revenue = $10,000.
6. Yield Percentage
How much usable product you get after trimming, cooking, etc.
Yield % = (Usable weight ÷ Purchased weight) × 100
Example: You buy 10 lbs of whole fish, after cleaning you have 6 lbs of fillets. 6 ÷ 10 = 60% yield
This matters for costing: if salmon is $12/lb wholesale but yields 60%, your actual cost per usable pound is $12 ÷ 0.60 = $20/lb.
7. Break-Even Point
Break-Even = Fixed Costs ÷ (1 − Variable Cost %)
Example: Fixed costs (rent, insurance, salaried labor) = $25,000/month. Variable costs (food, hourly labor) = 55% of revenue. $25,000 ÷ (1 − 0.55) = $55,556/month needed to break even.
Weekly Food Cost Review
Every Monday morning, 15 minutes:
- Calculate last week's food cost %
- Compare to target — are you above or below?
- Check the top 5 highest-cost items — any price spikes from vendors?
- Review waste log — any patterns?
- Action item: one specific thing to improve this week
Quick Reference
| Metric | Formula | Target |
|---|---|---|
| Food Cost % | COGS ÷ Revenue × 100 | 28–35% |
| Plate Cost | Sum of ingredients | Varies |
| Menu Price | Plate Cost ÷ Target % | 3–4x cost |
| Yield % | Usable ÷ Purchased × 100 | Item-specific |
| Pour Cost (bar) | Liquor Cost ÷ Bar Revenue × 100 | 18–24% |
Sideworks includes built-in food cost and break-even calculators so you can run these numbers without a spreadsheet.
