How to Calculate Prime Cost for a Restaurant (And Why It Matters)
Last updated: April 22, 2026
Prime cost is the single most important number on your P&L, and most restaurant operators either calculate it wrong or check it once a month when it's already too late to fix. If prime cost climbs above 65% of sales, you are almost certainly losing money — even if your bank account still looks okay this week.
The industry benchmark for a healthy full-service restaurant is a prime cost between 55% and 60% of total revenue. Quick-service and fast-casual operators should target 60% to 65%. Go above that, and every category of fixed cost — rent, utilities, insurance, debt service — has to be paid out of a shrinking pool.
What is prime cost in a restaurant?
Prime cost is the sum of your total Cost of Goods Sold (COGS) plus your total labor cost, including payroll taxes and benefits, for a given period. It represents the two largest controllable expenses in your restaurant and is tracked as a percentage of total revenue. Operators who manage prime cost weekly consistently outperform those who only review it monthly.
The Prime Cost Formula
Prime Cost = Total COGS + Total Labor Cost
Prime Cost Percentage:
Prime Cost % = (Prime Cost Ă· Total Revenue) Ă— 100
COGS includes every ingredient, every beverage, every paper good, every disposable, and yes — your fryer oil. Labor cost includes wages for all employees (hourly, salaried, tipped), payroll taxes (FICA, FUTA, SUTA), workers' comp premiums, and any benefits or bonuses paid during the period. Missing any of these will understate your real prime cost and paint a misleading picture.
Step-by-Step: How to Calculate Prime Cost
Count everything in your walk-in, dry storage, and freezer at the start of the period. Value it at current cost.
Pull every invoice — produce, protein, dairy, dry goods, paper, oil, beverages. Every category.
Count everything again at the end of the period. The difference is your true COGS — not what you purchased.
Pull gross wages from payroll. Add payroll tax burden (typically 10–12% on top of gross). Add workers' comp and benefits.
That's your prime cost percentage. Run this calculation weekly — not monthly.
A Worked Example
Let's walk through a real week for a 90-seat full-service restaurant doing $48,000 in weekly revenue.
| Line Item | Amount | % of Revenue |
|---|---|---|
| Total Revenue | $48,000 | 100% |
| Beginning Inventory | $14,200 | — |
| Purchases | $15,800 | — |
| Ending Inventory | $14,600 | — |
| Total COGS | $15,400 | 32.1% |
| Gross Payroll | $12,100 | — |
| Payroll Taxes & Benefits | $1,600 | — |
| Total Labor | $13,700 | 28.5% |
| Prime Cost | $29,100 | 60.6% |
In this example, prime cost lands at 60.6% — right at the edge of healthy. Shave two points off (either food or labor) and the operator keeps roughly $960 more every single week. That's nearly $50,000 a year from a two-point improvement.
Industry Benchmarks: What Good Looks Like
According to data tracked by the National Restaurant Association, pre-tax profit margins at typical full-service restaurants average between 3% and 5%. That thin margin is exactly why prime cost management isn't optional — it's the fulcrum that the entire business rests on.
Why Your Prime Cost Is Higher Than It Should Be
When prime cost creeps above benchmark, the cause is almost always one (or several) of the following:
1. You're only counting inventory monthly
Waste, spoilage, theft, and over-portioning happen daily. By the time you see a monthly variance, you've already lost the money. Weekly inventory is the single highest-ROI habit an operator can build.
2. You're not tracking oil and paper as COGS
Fryer oil, disposables, and cleaning chemicals routinely account for 2–4% of COGS and get lumped into "supplies" instead. That misallocation hides real variance and makes menu costing inaccurate.
3. Your menu isn't engineered
Items with food cost percentages above 35% should either be re-priced, re-portioned, re-sourced, or removed. A menu matrix (stars, plowhorses, puzzles, dogs) reveals exactly which items are silently draining margin.
4. You're scheduling to forecast, not to sales
Labor cost percentage spikes when sales drop. If you don't cut hours in real time based on covers and sales-per-labor-hour (SPLH), labor will run away from you during slow dayparts. According to Restaurant Business Online, top-quartile operators check labor percentage every 30 minutes during service using their POS.
Real Kitchen Example
A three-unit burger concept in suburban Chicago was running a 67% prime cost across all locations and couldn't understand why. The owner ran monthly inventory and reviewed P&Ls with her CPA six weeks after each month closed — so problems were two to three months old before she saw them.
She switched to weekly inventory on Sunday nights, built a simple Google Sheet that calculated prime cost every Monday morning, and reviewed it with each general manager on Tuesday at 10am. Within eight weeks:
- Food cost dropped from 34.8% to 31.2% (caught portioning drift on the double-patty burger — kitchen was running 4.4oz instead of 4.0oz)
- Labor cost dropped from 32.1% to 29.6% (cut one closer per location after identifying SPLH below $50 after 9pm)
- Fryer oil costs alone dropped 18% after she separated it from "kitchen supplies" and a manager noticed one location was ordering oil twice as often as the others
Total prime cost came down to 60.8%. On $4.2M in annual revenue, that's about $260,000 in additional operating margin — from better measurement, not from cuts.
How Often Should You Calculate Prime Cost?
Weekly, without exception. Any operator running prime cost on a monthly cadence is flying blind for 25 out of every 30 days. The weekly cadence also aligns with how labor is scheduled (weekly) and how most food purchases flow (multiple deliveries per week).
Top operators go one step further: they calculate a mid-week "flash" prime cost using Tuesday-through-Thursday data to project the full week and make corrections on Friday and Saturday — the highest-revenue days of the week.
Fryer Oil: The Hidden COGS Line
Fryer oil is one of the most frequently miscategorized COGS items. For most concepts with a fry program, oil represents 1–3% of food cost — a significant line that most operators never track separately. If you don't know what your oil line is doing, you can't manage it. A simple starting point is our Frying Oil Cost Calculator, which separates oil out as its own line in your COGS model. Extending oil life through proper filtration is one of the lowest-effort, highest-ROI moves available — our guide on how to extend frying oil life walks through the mechanics.
People Also Ask: What is the difference between prime cost and food cost?
Food cost is only one component of prime cost. Food cost percentage measures what you spent on ingredients and beverages divided by total revenue — typically 28% to 35% for most restaurants. Prime cost adds total labor (including taxes and benefits) on top of food cost, and measures both as a combined percentage of revenue. Food cost tells you how well you're buying, portioning, and pricing. Prime cost tells you whether the entire operation is financially viable. You can have a great food cost and still go out of business if labor runs away — and vice versa. Always manage both together.
Sources
- National Restaurant Association — Industry Research and Benchmarks
- Restaurant Business Online — Operations and Finance Coverage
- Purimax — Frying Oil Cost Calculator
- Purimax — How to Extend Frying Oil Life
