Restaurant Prime Cost: The One Number to Run By

Most restaurant owners can tell you their food cost percentage off the top of their head. Fewer can tell you their restaurant prime cost — and that second number is the one that actually decides whether the month ends in profit or apology. Prime cost combines your two largest and most controllable expenses into a single figure. If you only have the attention to watch one number closely, watch this one.

This post covers what prime cost is, why it's more honest than food cost alone, how to calculate it every week instead of waiting for the accountant, the realistic target band for different concepts, and what to actually do when the number climbs too high.

What prime cost actually is

Prime cost is the sum of two things, expressed as a percentage of sales:

• Cost of goods sold (COGS): all the food and beverage you bought and used to make what you sold.
• Total labour: every dollar tied to staffing — hourly wages, salaries, overtime, plus the parts people forget: payroll taxes, workers' comp, benefits, and any bonuses.

Add those two together, divide by total sales for the same period, and you have prime cost.

`` Prime cost % = (COGS + Total labour) / Total sales ``

The word "total" in labour is doing heavy lifting. Wages alone understate what a person really costs you. Payroll taxes and benefits can add a meaningful load on top of the base wage, and if you leave them out, your prime cost looks healthier than it is. Include them.

Why it beats food cost percentage alone

Food cost percentage is useful, but on its own it's easy to game — and easy to be fooled by.

Imagine you're worried about a high food cost, so you switch to cheaper ingredients and simplify prep. Food cost drops. Feels like a win. But the cheaper approach needed an extra prep cook, and the simpler menu slowed the line so you added a runner on weekends. Your labour just quietly rose more than your food fell. Food cost percentage says you improved. Prime cost says you got worse.

The two costs trade against each other constantly. Convenience products (pre-cut, pre-portioned, par-cooked) raise food cost but cut labour. Scratch cooking lowers food cost but demands more skilled hours. Neither is right or wrong in the abstract — what matters is the combined result as a share of sales. Prime cost is the only view that captures the trade-off honestly, because it refuses to let a win in one column hide a loss in the other.

That's the whole argument for it: it's the number you can't fool by shifting cost from one bucket to another.

The realistic target band

Here's the honest version, because precise-sounding benchmarks are usually made up. There's no single correct prime cost, and any source quoting one to the decimal is overselling.

As a widely used operator rule of thumb, many full-service independents aim to keep prime cost somewhere in the low-to-mid 60s as a percentage of sales. Push much above the mid-60s for a sustained stretch and the remaining margin has to cover rent, utilities, insurance, marketing, repairs, and debt — which is a hard squeeze. Treat that as a compass heading, not a law. Your rent, your concept, and your market all move the target.

Counter-service and full-service differ for structural reasons, not because one is run better:

• Counter-service / quick-service carries lighter labour — fewer servers, faster table turns or no tables at all — so it can often run a lower prime cost and absorb a slightly higher food cost.
• Full-service carries heavier labour — servers, bartenders, bussers, a deeper kitchen brigade — so labour eats a larger share and the food side usually has to be tighter to compensate.

A bar-forward concept shifts things again, since beverage COGS behaves very differently from food. The point isn't to hit someone else's number. It's to know your baseline, then watch which direction it moves.

Calculate it weekly, not monthly

Monthly prime cost is an autopsy. By the time the month closes, the four weeks that caused the damage are already gone. Weekly prime cost is a check-up — close enough to the action that you can still change the outcome.

You don't need perfect numbers to run it weekly. You need consistent ones. Here's a workable cadence:

1. Sales: pull total sales for the week from your POS. This is the easy part.
2. Labour: total your gross payroll for the week, then apply a standard uplift for taxes and benefits so you're using a fully loaded labour figure, not just wages.
3. COGS: you don't have to take a full inventory every week. A common shortcut is purchases as a proxy — sum what you spent on food and beverage that week. Over a few weeks the noise averages out. For a truer number, do a lightweight count of your highest-value items (proteins, liquor) and let the rest ride on purchases.
4. Divide and log it: (COGS + loaded labour) ÷ sales. Write it down. One line per week.

The logged trend matters more than any single week. One high week during a slow holiday tells you little. Three climbing weeks in a row tells you to act.

A worked example

Use round, hypothetical numbers to see the shape of it:

• Weekly sales: $50,000
• Food and beverage purchases (COGS proxy): $15,000 → 30% of sales
• Gross payroll: $14,000, plus a 20% load for taxes and benefits → $16,800 fully loaded → 33.6% of sales
• Prime cost: ($15,000 + $16,800) ÷ $50,000 = $31,800 / $50,000 = 63.6%

That 63.6% is the number to track week over week. If sales dip to $45,000 next week but costs barely move, prime cost jumps toward 70% — and you'll see it immediately, while there's still time to trim next week's schedule or tighten ordering.

The levers to pull when it's too high

When prime cost creeps up, the instinct is to cut staff on the floor. Resist that — gutting service to save a point of labour usually costs you more in slower turns, weaker checks, and lost regulars. Pull these instead:

• Schedule to the forecast, not to habit. Build the roster from expected covers by daypart. Over-staffing a quiet Tuesday is pure waste; the fix is timing, not fewer good people.
• Attack waste and over-portioning. Spoilage, inconsistent portions, and comps quietly inflate COGS. Standardize portions and track waste for two weeks — it's often the cheapest point you'll ever recover.
• Fix menu pricing and mix. Some dishes carry the house; some bleed. Nudge prices where the market allows, and steer guests toward high-margin items through menu placement rather than cutting quality.
• Renegotiate and consolidate purchasing. Check your top ten invoice lines against alternatives. Consolidating suppliers or adjusting spec on a few high-volume items can move COGS without any guest ever noticing.
• Cross-train for flexibility. Staff who cover two stations let you run leaner on slow shifts without leaving a hole on busy ones.

Notice that none of these mean worse food or slower service. Prime cost management is about precision, not austerity.

Measure it this week

Don't wait for a system or a perfect process. This week, pull your sales from the POS, total your fully loaded payroll, sum your food and beverage purchases, and do the one division. Write the percentage on a whiteboard where the team can see it. Do it again next week. Within a month you'll have a trend line — and a trend line is what turns prime cost from a bookkeeping term into a steering wheel.

If your POS already holds your sales and labour hours, most of the weekly math is sitting in one place, which makes the habit far easier to keep. But the tool matters less than the habit. Run the number this week, and let it run your restaurant from here on.