Labor cost percentage — wages as a share of sales — is the number that catches overstaffing before it quietly eats a month's profit. Tracked by shift instead of only monthly, it also catches the specific Tuesday lunch or slow Sunday that's bleeding margin while the rest of the week looks fine.
How labor cost percentage and prime cost are calculated
Labor cost dollars for a shift equal wages paid, grossed up by an estimated payroll tax and burden rate (typically 8-12% depending on your state and benefits structure). Divide that by the shift's sales to get labor cost percentage. Add your food cost percentage to labor cost percentage and you get prime cost — the combined cost of the two largest line items in almost every restaurant's P&L, and the single number most consultants watch first.
Tracking this by shift rather than only by week or month surfaces problems a monthly rollup smooths over — a chronically overstaffed Tuesday lunch can hide inside an otherwise healthy weekly average.
Why flat, monthly-only labor tracking gets this wrong
A single monthly labor cost percentage tells you whether the month, on average, was efficiently staffed. It can't tell you which specific shifts drove that number, which means it can't tell you what to actually change on next week's schedule. Shift-level tracking turns a lagging, monthly report into a forward-looking scheduling tool.
Worked example
A Friday dinner shift pays $900 in wages against $4,200 in sales, plus a 10% payroll burden — $990 in true labor cost, a 23.6% labor cost percentage. A Saturday dinner shift pays $950 against $4,800 in sales — $1,045 with burden, 21.8%. Combined across both shifts, labor cost runs 22.7% of sales. Add a 30% food cost and prime cost lands at 52.7% — comfortably under the commonly cited 60-65% target range.
Common mistakes and benchmarks
- Forgetting payroll burden.Wages alone understate true labor cost — payroll taxes, workers' comp, and benefits typically add another 8-15% on top of gross wages.
- Only reviewing labor cost monthly.By the time a monthly number looks bad, the specific overstaffed shifts that caused it are long past. Weekly or shift-level review catches the pattern while it's still fixable.
- Chasing labor cost % without watching prime cost. Cutting labor too aggressively can push food cost up (via slower prep, more waste, or service issues that hurt sales) even as labor cost % improves. The seasonal break-even calculator is a useful companion for seeing how staffing decisions interact with monthly profitability overall.