Restaurant prime cost: the number that connects food and labor

During lunch service, the kitchen brigade plates dishes at the pass

Prime cost adds the cost of food consumed and labor cost, then divides the total by sales excluding tax. It checks that a saving on food is not being paid for in working hours, and the other way around. It is a detector of shifts between two cost lines, not a verdict on a site.

Buying prepared garnish: the time saved that costs

A fictional example. A chef decides to buy a ready-made garnish to free up time on the cold station. Food cost goes up slightly, but the morning prep team gets shorter. The manager cuts the schedule accordingly. The same month, another site makes the opposite choice: it works more with raw products, its food cost goes down, but it keeps one more hour of prep every morning. Looked at separately, each number says something contradictory. Looked at together, you can compare the two choices.

The formula and its ingredients

Prime cost = (cost of food consumed + labor cost) / sales excl. tax

Details to set in writing, once:

Cost of food consumed: opening stock + purchases - closing stock, over the period.
Labor cost: what you include (wages, payroll charges, extra staff, bonuses, staff meals). The definition does not change from one month to the next.
Sales excl. tax: over the exact same period.

Why a total? Because many decisions move cost from one line to another: buying prepared, producing in-house, changing a portion, adjusting the prep team, revising the menu.

How people go wrong with prime cost

Mismatched periods. The week's purchases, the month's payroll, the fortnight's sales: the ratio no longer means anything.
Moving definitions. Counting extra staff one month and not the next creates a fictional variation.
A total that hides the causes. A stable prime cost can hide food cost going up and labor going down, and that is a signal.
Comparing sites without comparing their model. A central kitchen, an on-site kitchen and a short-menu site do not have the same structure.
Reading it as a target. Setting a target on the total pushes you to sacrifice whatever shows up most slowly (quality, training, prep).

Using prime cost in five steps

Fix the definitions. One page, signed off by the owner and the accountant: what goes into food, what goes into labor.
Calculate the three numbers over the same period. Food cost, labor ratio, prime cost. Tool: a monthly table per site, read every week in partial form.
Look at the composition, not only the total. A stable total with food cost rising and labor falling is a warning, not good news.
Link each variation to a dated decision. Supplier change, purchase of prepared products, schedule change, menu change.
Decide on the cause. When the total moves, look at recipes, tasks, hours and training before cutting anything.

An example of cross-reading

What moves	Likely effect on food	Likely effect on labor	What to check
Buying prepared products	Up	Down if the schedule follows	Did the schedule really change?
Return to made-in-house	Down	Up	Are the extra hours absorbed?
Cutting prep hours	Possible rise in waste	Down	The period's waste
New, shorter menu	Possible drop	Variable	Did the prep change?

When prime cost is not enough

Prime cost leaves out rent, energy, fixed costs and selling price. A stable prime cost with a falling average check is not good news. Always read it with sales, guest traffic and the menu. It is a cross-checking tool, not a full results table, and it does not replace your accountant's advice.

What to measure

Prime cost, with its two components displayed side by side, on a constant definition.
The number of variations explained by a dated decision, compared with those that remain unexplained.
The stability of definitions: how many times a definition changed over the half-year. Ideally, none.

Where Tsuno comes in

Tsuno keeps recipes, tasks by station, skills and the schedule, along with the decisions made and their date. This lets you link a move in prime cost to an identifiable cause: a changed recipe, a reorganized station, a modified instruction. Sales, invoice and payroll figures come from your tools, which you keep: the import is done with human validation. Tsuno replaces neither your POS nor payroll. To place your labor-to-sales ratio, a calculation runs in your browser on the measure my gain page.

Key takeaways

Read prime cost as a whole: food plus labor, same period, same definitions. It flags a shift, then you look at the process to explain it.

Further reading: why owners discover cost drift too late, food cost that arrives too late, the arbitrary hours budget and the real cost of waste.

Frequently asked questions

How do you calculate a restaurant's prime cost?

Prime cost = (cost of food consumed + labor cost) / sales excluding tax. Both costs must cover the same period as the sales, with definitions that stay constant from one month to the next.

Why look at prime cost rather than food cost alone?

Because a drop in food cost can be paid for in extra prep hours. Conversely, saving hours can push waste up. Prime cost shows the total of both effects.

Is there an ideal prime cost to aim for?

There is no universal value. The right level depends on your concept, your menu and your site. The most useful thing is to follow your own trend, with a stable definition, and to explain it.

Which labor costs should you include?

Decide once and write it down: wages, payroll charges, extra staff, bonuses, benefits in kind. What matters is not changing the definition from one month to the next, otherwise the comparison means nothing.

Is prime cost enough to judge a site?

No. It says nothing about rent, energy or selling price, and it does not say why. It is for spotting a shift between food and labor, then looking for the cause in the process.