Restaurant Prime Cost: Calculate It Consistently and Find the Cause of Change
Prime cost brings two important operating costs together: cost of goods sold and labor. It can help you see where to investigate, but it does not establish total profit by itself.
Calculate it consistently, compare it with your operating plan, and then separate the reasons it changed.
Use matching inputs
Prime cost equals COGS plus labor cost. Prime cost percentage divides that sum by the matching sales amount and multiplies by 100. Restaurant365 documents these formulas and the need to include employer labor costs, not only hourly wages. Prime-cost calculation guide.
Use the same location, period, and accounting definitions for every input. Do not combine a calendar month's sales with a payroll period that crosses into the next month without the appropriate allocation.
Illustrative arithmetic: $30,000 COGS plus $25,000 labor gives $55,000 prime cost. Dividing by $100,000 net sales gives 55%. Those hypothetical inputs demonstrate the formula; they are not a recommended target or a customer result.
Check what is inside COGS
Begin with opening inventory plus purchases minus closing inventory. Account for transfers, credits, and other adjustments consistently with your finance team's policy. The food-cost variance guide expands the count, purchasing, and recipe checks behind this component.
Purchases alone are not usage. A large delivery near period-end may increase purchases and ending inventory together. A missing count can therefore distort the apparent cost even when ordering has not changed.
Inspect pack sizes, count units, and recipe versions when comparing locations. An apparent food-cost problem may begin with mismatched measurement.
Check what is inside labor
Agree which wages, salaries, employer taxes, benefits, and related costs belong in the measure. Label daily estimates if they omit components that arrive later. The labor cost calculator helps check labor against matching sales inputs; keep its target gap separate from verified savings.
Then separate hours, rate mix, and demand. A higher labor percentage does not automatically mean more hours were worked; lower sales can change the ratio without a spending increase.
Set a target from the business model
Use your budget, service model, local costs, and comparable operating history. A universal cutoff cannot decide whether a particular restaurant is profitable. Occupancy, overhead, financing, and other costs still matter.
Compare the prime-cost change in dollars as well as percentage points. Then separate the COGS and labor components so each manager knows what question to investigate.
Review by location before consolidating
Calculate the group percentage from group costs divided by group sales. Avoid simply averaging location percentages when their sales differ.
For each material exception, record the source, cause, action, owner, and next review. If a menu item has a high food-cost percentage, also inspect its dollar contribution and role in the menu before removing it. If labor looks high, preserve the staffing required for service and applicable work rules.
Reuse a period input checklist
| Input | What to record before calculating |
|---|---|
| Scope | Location, period start/end, sales definition |
| COGS | Opening inventory, purchases, closing inventory, reconciled adjustments |
| Labor | Included wage, salary, employer-cost components and allocations |
| Sales | Matching period and scope; source report |
| Calculation | COGS + labor; divide by matching sales for percentage |
| Comparison | Budget or comparable period; dollars and percentage points |
| Follow-up | Component that changed, evidence, owner, next review |
Mark estimates and missing components. Recalculate when final records arrive, and retain enough history to explain why the result changed.
Turn a prime-cost change into a managed action
Marty is a managed profit-control layer for multi-unit restaurants.
Find → Assign → Follow up → Verify. Find whether the supported change comes from COGS, labor, sales, or a reporting issue. Assign the relevant owner. Follow up on the agreed action and escalate missed work. Verify the later cost and service context rather than declaring success from a lower ratio alone.
The paid Cash Recovery Plan establishes the baseline that tells Marty what to watch first.
Optional Managed Profit Control adds monitoring, alerts, follow-up, escalation, and verification for the agreed cost controls selected from the location diagnosis.
Sources checked September 15, 2026: linked Restaurant365 formula guidance and Marty's Review offer. Calculated example is hypothetical; target-setting recommendations are editorial guidance.