What this number actually tells you
Revenue tells you what came in. Profit tells you what stayed. Prime cost tells you whether the way you turn one into the other can keep doing what it just did. It is the only weekly number that answers the operator’s real question: did I just have a healthy week, or did I get lucky?
Independent full-service restaurants live in a 55–65% prime-cost band. Coffee bars and counter-service can run lower. Fine dining and high-labor concepts run higher. The exact target depends on your model, but the band is real — below 50% almost always means you under-counted labor, and above 70% almost always means you are subsidizing the line out of pocket and do not yet know it.
What the math is doing
The formula is simple by design.
Prime cost % =
(COGS + fully-loaded labor) ÷ net sales
COGS is the food and beverage you actually used this week — purchases, plus an inventory adjustment for what grew or shrank in the walk-in. Net sales is what landed in your bank account from selling food and drink, before sales tax. Fully-loaded labor is wages plus the parts you wish you could ignore: employer payroll taxes, your share of health benefits, the salaried managers you tend to forget about because their pay is automatic.
The division is what makes it a verdict. Sixty thousand dollars of sales last week could mean you ran a hot kitchen or that you ran a panicked one. The percentage tells you which.
The four lies operators tell themselves
Almost every artificially-low prime cost falls into one of four traps. None of them are dishonest on purpose; all of them are the kitchen-side version of cooking your own books.
Skipping employer taxes. Wages are gross-pay times hours worked — everyone counts those. The employer side — FICA match, federal and state unemployment, your share of health and benefits — runs another 12 to 18% on top. Leaving them out makes labor look 12 to 18% smaller than it is. The fix is one line in the worksheet: add employer payroll taxes & benefits to the labor section.
Forgetting salaried management. The chef-owner who pulls $1,800 a week is labor. The general manager who clears $1,400 is labor. The bookkeeper who comes in twice a week to run payroll is labor. If they touch the operation, their pay is in the formula. The most common silent error is the owner-operator who pays themselves last and assumes that means the labor line does not include them. It does.
Treating spilled inventory as zero. The walk-in counts on Sunday and Friday. The difference between the two is your inventory adjustment. If you bought $14,000 of food this week but used only $12,500 worth, the other $1,500 sat on the shelf — COGS for this week is $12,500, not $14,000. The reverse is true too: if you started Sunday with a full walk-in and ended Friday empty, you used more than you bought. The adjustment line catches this. Skipping it makes a slow week look hot and a hot week look slow.
Mixing channels. Delivery orders carry kitchen labor too. The expo who packs them, the cook who batches them, the dishwasher who runs the extra clamshells — all of that is labor that exists because the channel exists. Prime cost across all channels is the right number; pretending delivery is “extra” revenue with no labor cost is how operators end up subsidizing platforms quietly. The third-party channel P&L sheet exists to keep that math honest.
Reading the verdict bands
The worksheet returns a percentage and colors it green, yellow, or red. The colors are not opinions — they are operational instructions.
Green — below 60%. Healthy. The week was a good one and the model worked. The action: don’t change anything; the discipline that produced it is what protects next week.
Yellow — 60 to 65%. The upper band. You are still solvent but the cushion is gone. Look at the two lines — food cost percent and labor cost percent — and find the bigger driver. If food crept up, the recipe cost cards on your top three SKUs are the next 30 minutes of your week. If labor crept up, the schedule for next week needs a one-shift trim.
Red — above 65%. Margin emergency. At this band, every additional dollar of sales is losing you money once fixed costs (rent, insurance, utilities) are layered on. The action is non-optional and falls on whichever line is bigger. If labor is over 35% you have a scheduling problem; if food is over 33% you have a vendor or portion problem. Pick the one with more zeros and start there.
A four-week protocol for getting stable
If you are running this sheet for the first time, do not try to fix anything in week one. The job in week one is to establish what your honest number actually is.
Week 1 — Run it as honestly as you can. Include every wage line, every employer tax, every channel. Do the inventory adjustment. Write down whatever the percentage is, even if it embarrasses you. The number on the page is the number; the discomfort is the work.
Week 2 — Run it again, identically. No interventions yet. The second week confirms the first — if your first week landed at 68% and your second week lands at 67%, you have a structural problem to solve, not a one-week anomaly to wait out.
Week 3 — Pick the bigger line. Look at food vs labor. Whichever is the bigger driver gets the intervention. If food, run the recipe cost card on the three SKUs that move the most volume; reprice or repackage them. If labor, run the schedule for week 4 with one fewer shift on the slowest day; see what the prime cost does.
Week 4 — Compare. The fourth week’s prime cost should move at least 1.5 percentage points from week 1. If it moves more, you found a real lever and can repeat the move. If it moves less, the lever you pulled was not the right one and you go back to the bigger line and try the other half — food side, labor side. Four weeks is enough to find the trunk problem; eight weeks is enough to fix it.
What changes when prime cost is healthy
The other thirty sheets in the catalog start working differently. The recipe cost card stops being a defensive exercise and becomes a pricing tool. The monthly P&L snapshot stops surprising you. The channel P&L stops being a question of survival and becomes a question of growth. None of those sheets get easier to fill, but they all start telling you what to do next instead of what you should already have done.
Prime cost is the trunk because every other operating decision branches off it. A menu price you set without knowing your prime cost is a guess. A delivery channel you keep without knowing your prime cost is a hope. A staff schedule you build without knowing your prime cost is a habit. Knowing the number does not replace any of those judgment calls — it just gives them somewhere to land.
Open the sheet: Weekly Prime Cost Worksheet →
Tuesday morning, fifteen minutes, prior week’s numbers. The math runs in your browser. Your numbers never leave the page.