Restaurant Prime Cost: The Number That Decides Whether You Profit
By PlainSight — Insightful Actions · Updated July 2026 · ~7 min read
Restaurants fail with full dining rooms. Sales tell you how busy you were; prime cost tells you whether being busy was worth it. If you read only one number every week, read this one — and then read the three that explain it.
What prime cost is
Prime cost is your cost of goods sold plus total labor, expressed as a percentage of sales. It bundles the two costs you actually control day to day, which is exactly why operators watch it instead of chasing net profit monthly.
Prime cost = (food and beverage cost + total labor cost) ÷ sales. Many full-service operators aim to keep this in the mid-fifties to mid-sixties percent of sales, but the workable range varies enormously by concept, service model, and market. Your own trend matters far more than any benchmark.
The reason it works as a single indicator: if prime cost drifts up, one of two things is happening — you are paying more for what you sell, or you are paying more people to sell it. Both are fixable, and both are invisible in a sales report.
The numbers underneath it
1. Food and beverage cost percentage
What good looks like: stable week to week, and stable across similar weeks last year.
Track food and beverage separately — they behave differently and beverage usually carries far better margin. A sudden move is almost always price increases from a supplier, portioning drift, waste, or theft, in that order of likelihood.
2. Labor cost percentage
What good looks like: flexing with sales rather than staying flat through slow shifts.
Split front of house from back of house. Fixed-feeling labor during a slow daypart is the most common controllable loss in the business, and your POS already tells you which hours those are.
3. Average check and covers
What good looks like: both understood by daypart rather than blended.
Sales equal covers times average check, so a revenue change is always one or the other. Knowing which tells you whether you have a traffic problem or a spending problem — two completely different fixes.
4. Sales per labor hour
What good looks like: consistent across comparable shifts.
This is the cleanest productivity measure in a restaurant, because it accounts for both volume and staffing at once. Compare the same daypart across weeks before comparing lunch to dinner.
5. Menu mix and item contribution
What good looks like: your high-margin items among your best sellers.
Rank items by units sold and by contribution margin. The classic four quadrants apply: high-popularity high-margin items to protect and feature, high-popularity low-margin items to reprice or re-cost, low-popularity high-margin items to promote or reposition, and low-on-both items to cut. Menu space is not free.
6. Waste, comps, and voids
What good looks like: small, stable, and always attached to a reason code.
This is margin that leaves without a decision being made. A comp rate creeping up half a point per month is a meaningful annual number, and it is nearly always a policy that quietly loosened.
7. Daypart contribution
What good looks like: every service period you staff earning its keep.
Break sales and labor down by daypart. A lunch service that runs at break-even while consuming management attention is a legitimate strategic decision — but it should be a decision, not a discovery.
Read it weekly, not monthly
Monthly financials arrive too late to change anything. Prime cost read weekly is early enough to adjust ordering, portioning, and schedules while the month is still in progress. Most operators who turn a business around describe the same habit: a short, boring weekly number review that never gets skipped.
Three leaks worth hunting
- Menu items that sell well and earn little — often the loudest item on the menu, and a small price or recipe change moves real money.
- A daypart staffed for a rush that stopped happening — check sales per labor hour by hour, not by shift.
- Third-party delivery growth — commission means your effective margin on those orders is materially lower than dine-in, so growth there is not equivalent to growth here.
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Frequently asked questions
- What do I need to calculate prime cost?
- Sales for the period, your food and beverage cost for that period, and total labor including taxes and benefits. Sales come from your POS; cost figures come from invoices and payroll.
- Why weekly instead of monthly?
- Because a month closes after you can do anything about it. Weekly gives you time to change ordering, portioning, and scheduling while the results still matter.
- Is there a target prime cost?
- Many full-service operators watch for the mid-fifties to mid-sixties percent of sales, but concept, service model, and local wages shift that a great deal. Your own trend is a more reliable guide than any published number.
- Can PlainSight calculate prime cost for me?
- PlainSight reads your sales export directly — revenue, average check, dayparts, and item mix. Food cost and labor come from invoices and payroll, so bring those figures alongside for the full prime cost picture.
This guide is general information for business owners, not financial, tax, or legal advice. Figures described as “typical” are rules of thumb that vary widely by market and model — always read your own numbers in context.