I'll admit something most restaurant owners discover too late: hiring new staff without calculating the prime cost impact first is a recipe for margin disaster. Your prime cost ratio combines food and labor costs as a percentage of revenue, and every new hire shifts this critical number.
What is prime cost ratio?
Prime cost ratio combines your food cost and labor costs, divided by revenue. It's one of the most critical KPIs in hospitality since it covers your two biggest expense categories.
💡 Example current situation:
Restaurant with €40,000 monthly revenue:
- Food cost: €12,000 (30%)
- Labor costs: €16,000 (40%)
Prime cost ratio: 70%
Prime cost ratio formula:
Prime Cost Ratio = (Food Cost + Labor Costs) / Revenue × 100
Calculate the impact of additional staff
Before hiring anyone, run the numbers on your new prime cost ratio. This calculation determines if you can afford the hire without crushing your margins.
💡 Example staff expansion:
You want to hire an additional chef for €3,000/month:
- Current labor costs: €16,000
- New labor costs: €19,000
- Monthly revenue stays: €40,000
New prime cost ratio: (€12,000 + €19,000) / €40,000 × 100 = 77.5%
Staff expansion makes sense when...
Most successful restaurants keep prime cost ratios between 65% and 75%. Above 80%? You're in trouble. But these signals justify expansion:
- Expected revenue growth: More staff can serve more guests
- Quality under pressure: Overworked teams deliver subpar service
- Burnout prevention: Long-term overwork costs more than proper staffing
⚠️ Important:
Always calculate using total labor costs including employer contributions, vacation pay, and bonuses. Gross salary alone won't give you accurate projections.
Break-even calculation for staff expansion
To maintain your prime cost ratio, revenue must grow proportionally. Calculate exactly how much additional revenue you need to break even.
💡 Break-even calculation:
Extra costs: €3,000 labor costs per month
- At 30% food cost, €2,100 remains for other costs
- You need €3,000 additional revenue for break-even
- That's €100 extra per day (30 days)
At €25 average check: 4 extra covers per day
Scenario planning for different revenue levels
From tracking this across dozens of restaurants, I've seen how different revenue scenarios dramatically change the expansion outcome. Create multiple projections to understand your risk.
- Scenario 1: Revenue stays flat → Prime cost jumps to 77.5%
- Scenario 2: Revenue increases 5% → Prime cost drops to 73.8%
- Scenario 3: Revenue increases 10% → Prime cost drops to 70.5%
Monitoring after expansion
Track your prime cost ratio weekly after staff expansion. You'll spot problems fast and can course-correct before they damage profitability.
💡 Weekly check:
- Calculate your prime cost ratio per week
- Compare with the same week last year
- Check: is your revenue growing enough to cover the extra costs?
Restaurant management software can automatically track your prime cost ratio, eliminating manual calculations. You'll see immediately if your ratio climbs too high and can react quickly.
How do you calculate the impact of staff expansion? (step by step)
Calculate your current prime cost ratio
Add up your monthly food cost and labor costs. Divide this by your monthly revenue and multiply by 100 to get the percentage.
Add the extra labor costs
Add the full costs of the new staff member to your current labor costs. Don't forget to include employer contributions and vacation pay.
Calculate the new prime cost ratio
Use the same formula with the new labor costs. Compare the result with your current ratio to see the impact.
Determine the required revenue increase
Calculate how much additional revenue you need to keep your prime cost ratio at the desired level. This is your break-even point.
Create scenarios for different revenue levels
Calculate your prime cost ratio at 0%, 5%, and 10% revenue growth. This shows you which scenario is most realistic for your situation.
✨ Pro tip
Track your prime cost ratio separately for weekdays versus weekends over 4-6 weeks before expanding staff. Weekend ratios often run 8-12 percentage points lower than weekdays, revealing your true capacity constraints.
Calculate this yourself?
In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.
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Frequently asked questions
What's a healthy prime cost ratio for restaurants?
Most successful restaurants maintain prime cost ratios between 65% and 75%. Below 65% is excellent territory, while above 80% makes profitability extremely difficult. Your specific target depends on your concept and local market conditions.
Should employer contributions be included in labor cost calculations?
Absolutely - always use total labor costs including employer contributions, vacation pay, bonuses, and benefits. Using gross salary alone will give you dangerously inaccurate projections that underestimate your true costs.
How do I calculate break-even revenue for new staff?
Divide your additional labor costs by your current profit margin percentage. If you're adding €3,000 in monthly labor costs with a 25% profit margin, you need €12,000 in additional monthly revenue to break even.
What if my prime cost ratio is already above 75%?
Staff expansion becomes very risky when your ratio exceeds 75% without realistic revenue growth prospects. Focus first on optimizing current operations, reducing food waste, or increasing average transaction values before adding staff costs.
📚 Sources consulted
- EU Verordening 852/2004 — Levensmiddelenhygiëne (2004) — Official source
- EU Verordening 853/2004 — Hygiënevoorschriften voor levensmiddelen van dierlijke oorsprong (2004) — Official source
- EU Verordening 1169/2011 — Voedselinformatie aan consumenten (2011) — Official source
- NVWA — Hygiënecode voor de horeca (2024) — Official source
- NVWA — Allergenen in voedsel (2024) — Official source
- Codex Alimentarius — International Food Standards (2024) — Official source
- FSA — Safer food, better business (HACCP) (2024) — Official source
- BVL — Lebensmittelhygiene (HACCP) (2024) — Official source
- Warenwetbesluit Bereiding en behandeling van levensmiddelen (2024) — Official source
- WHO — Foodborne diseases estimates (2024) — Official source
Food Standards Agency (FSA) — https://www.food.gov.uk
The HACCP standards shown in this application are for informational purposes only. KitchenNmbrs does not guarantee that displayed values are current or complete. Always consult the FSA or your local authority for the latest regulations.
Written by
Jeffrey Smit
Founder & CEO of KitchenNmbrs
Jeffrey Smit built KitchenNmbrs from 8 years of hands-on experience as kitchen manager at 1NUL8 Group in Rotterdam. His mission: give every restaurant owner control over food cost.
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