The 30% Rule and Why Most Restaurants Miss It
Industry benchmarks suggest food cost should represent 28–32% of food revenue for a full-service restaurant. Fast-casual targets 25–30%. Fine dining, with its premium ingredients, often runs 32–38%. Whatever your benchmark, the question is the same: are you hitting it, and do you know why when you are not?
Most restaurant operators know their monthly food cost percentage in arrears — they find out at month-end what the damage was. The operators who consistently hit their targets track food cost in near real-time, because the levers that drive food cost move daily: delivery prices, waste rates, portion variances, and staff consumption all change day to day.
The Five Drivers of High Food Cost
1. Poor Purchasing
Overpaying suppliers is the most direct food cost driver. Restaurants that do not get competitive quotes, do not track price changes across deliveries, and do not challenge invoice prices routinely pay 5–15% more than necessary. Benchmark every core ingredient against at least two suppliers quarterly. When a supplier raises prices, ask for justification and alternatives before accepting.
2. Over-Portioning
A recipe calls for 6 oz of salmon. Your line cook plates 7 oz because the piece is slightly large. That is a 16% food cost increase on that dish, for every service, across every table. Consistent portioning — measured by weight for proteins and sauces, by count for components — is the highest-leverage discipline in a kitchen.
Standard recipe cards, portion scales at every station, and regular portion audits close this gap. OneScale's recipe management module defines standard portions per dish and calculates the theoretical food cost, which you compare against actual cost to identify over-portioning trends.
3. Waste
Production waste (trim waste, cooking shrinkage, spoilage) is inherent in food production. The question is whether it matches expected levels. A kitchen producing 80 portions of chicken per service should have a predictable amount of trim and cooking loss. When actual waste exceeds this, something is wrong — poor knife skills, incorrect cooking temperatures, or excessive batch cooking.
Track waste by station and by shift. When waste is visible and measured, it reduces. When it is invisible, it grows.
4. Theft
Employee meal theft and deliberate over-portioning for friends are more common than most owners acknowledge. A standardised meal policy (what staff eat, when, recorded in the POS) and a culture of portion accountability reduce this significantly. POS void reports and discount patterns can identify unusual activity worth investigating.
5. Menu Engineering Errors
Some items on your menu cost more to produce than their selling price justifies. A dish with a 48% food cost might be popular but is actively destroying your overall margin. Menu engineering — analysing every item by food cost percentage and popularity — identifies these "plow horses" that deserve either a price increase, a portion adjustment, or removal.
The Theoretical vs. Actual Food Cost Gap
Theoretical food cost is what your food cost should be if every portion were exactly right and no waste occurred beyond expected levels. Actual food cost is what your accounting says it was. The gap between these two numbers is your "food cost variance" — and finding out where this variance comes from is the most valuable exercise in restaurant cost management.
OneScale's recipe costing calculates theoretical food cost from your production records. Comparing this against your purchasing spend reveals the variance. A persistent gap points to one of the five drivers above — and each one has a specific fix.
Practical Weekly Habits
- Monday: Review prior week's food cost percentage from POS sales and invoice data
- Wednesday: Spot-check portion weights on two or three core proteins
- Friday: Review waste log from each station; brief kitchen team on any variances
- Monthly: Full menu engineering analysis — food cost % and margin by dish
Conclusion
Controlling food cost is not a one-time project. It is a weekly discipline that compounds over time. Restaurants that track it systematically — comparing theoretical to actual, measuring portions, recording waste — consistently outperform those that manage by feel. The tools to do this are available to any operator, regardless of size.
