Prime Cost Explained: The One Restaurant Number That Matters
If you could track exactly one number in your restaurant, it should be prime cost. Not food cost. Not labor cost. Prime cost.
Here's why, and here's how to calculate it without fooling yourself.
If you’d rather not do the arithmetic by hand, our free Restaurant Prime Cost Calculator runs it from four numbers off your P&L.
The definition
Prime cost = total cost of goods sold + total labor cost.
Expressed as a percentage of total sales.
COGS is everything you sell: food, beverage, alcohol, paper and packaging if you count it there.
Total labor is everything you pay people: hourly wages, salaried management, payroll taxes, workers' comp, benefits, and any owner salary if you work in the business.
That second definition is where most owners understate their prime cost badly — in the worked example below, by eight points. Labor is not the wage line on your payroll report. It's the fully loaded cost. Payroll taxes and workers' comp alone typically add 10–15% on top of gross wages, and workers' comp for restaurants is not cheap.
The targets
Full service: 60% to 65% of sales
Quick service and fast casual: 55% to 60%
Above 70% and you are almost certainly losing money regardless of how busy the room looks. Below 55% in full service, either you've found something genuinely excellent or you've made an arithmetic error — check your labor definition first.
The reason these ranges are tight is that the remaining 35–40% has to cover rent, utilities, insurance, marketing, repairs, licenses, debt service, and profit. In most markets, occupancy alone eats 6–10%.
Why prime cost beats food cost
Food cost on its own is a trap, because food cost and labor cost trade against each other.
Buy pre-portioned proteins, pre-cut vegetables and par-baked bread and your food cost goes up while your labor goes down. Butcher and prep in house and food cost drops while labor climbs.
An owner watching only food cost will "fix" a 34% food cost by bringing prep in house — and add four points of labor to save two points of food. The food cost report looks better. The business is worse.
Prime cost is immune to that. It's the only number that tells you whether the trade you just made was a good one.
How to calculate it properly
Weekly, not monthly. Monthly is a post-mortem. Weekly is a steering wheel — you can still change the schedule and the order.
For COGS, use actual usage, not purchases.
COGS = opening inventory + purchases − closing inventory
If you use purchases instead, a week where you bought a lot of dry goods looks like a disaster and the following week looks like a triumph. Neither is true. This means you need a weekly inventory count, at least of your high-value items.
For labor, use the fully loaded number, and include salaried managers. If a manager's salary is $70,000, that's roughly $1,346 a week that belongs in the calculation whether or not they appear on the hourly report.
Include your own labor. If you work the line five days a week and don't pay yourself, your prime cost is fiction. Put a market-rate salary in there. The number that results is what the business actually costs to run, and it's the number a buyer or a lender will use.
A worked example
A neighborhood full-service restaurant, one week:
Sales — $48,000
Opening inventory — $14,200
Purchases — $14,900
Closing inventory — $13,600
COGS — $15,500 (32.3%)
Hourly wages — $11,800
Salaried management — $2,100
Payroll taxes + workers' comp (13%) — $1,807
Total labor — $15,707 (32.7%)
Prime cost — $31,207, or 65.0%
At the very top of the acceptable band. This restaurant is probably making a small profit and has no cushion. A slow month, a bad hire, or one equipment failure takes it negative.
Note what the naive version would have said: food cost 32.3% (fine!) and labor at $11,800 = 24.6% (great!). Total 57%. That restaurant thinks it's healthy. It isn't.
What to do when prime cost is too high
Work in this order, because that's the order of payback:
Menu engineering first. Find the items with high popularity and low contribution margin. Reprice or re-engineer those specific dishes. This is the fastest money in the building and it requires no negotiation with anyone.
Vendor bids second. If you haven't rebid your major categories in eighteen months, you are overpaying. Produce and paper are usually the easiest wins.
Waste and portioning third. Spot-check portions against spec. Track what goes in the bin for one week — it's always more than anyone expects.
Schedule against sales, not habit. Build the schedule from forecast covers by daypart. Most restaurants are overstaffed in one specific two-hour window and don't know which one.
Cut heads last. It's the most visible lever and usually the least effective, because it damages service and drives the sales line down faster than it drops the cost line.
Track it weekly
Prime cost is only useful as a trend. One week tells you nothing; twelve weeks tells you everything — whether your rebid worked, whether the new menu pricing held, whether that scheduling change actually landed.
Our Restaurant Operations Toolkit includes the food cost, prime cost, labor and break-even calculators alongside inventory sheets — 19 editable templates set up for weekly tracking, with the fully loaded labor and actual-usage COGS built into the formulas. Instant download.
Menu engineering is the first lever on that list, and it is the one most owners skip. Our Menu Optimization Report classifies every item on your menu by contribution margin and popularity for $19.95. Or book a free 20-minute consult and we will look at your prime cost with you.
