Most restaurant promotions lose money without owners realizing it. You might think that 20% off pasta special is bringing in customers, but it could be costing you €300+ monthly in lost margins. Stop guessing and start calculating which deals actually work.
Why math beats gut feeling for promotions
That 'buy one get one free' deal cuts your margin in half instantly. A blanket 15% discount across your menu might eliminate your entire monthly profit. You can't know if you're building business or bleeding cash without running the actual numbers.
⚠️ Watch out:
A promotion that 'feels right' can cost you hundreds of euros per month without you realizing it.
Three financial impacts every promotion creates
Each discount or special affects your bottom line in three ways:
- Direct costs: Immediate margin loss per discounted item
- Volume effect: Additional sales the promotion generates
- Substitution effect: Customers switching from higher-margin items
Calculate direct impact first
Start by figuring out what each promotional sale actually costs you.
? Example:
Salmon dish normally €22.50 (€20.64 excl. VAT)
- Food cost: €7.20
- Regular margin: €13.44
- 25% discount price: €15.48 excl. VAT
- Promotional margin: €8.28
Margin loss per dish: €5.16
Use this formula: (Regular price - Promotional price) = Direct loss per item sold
Measure the volume boost
How many extra covers does your promotion actually bring in? Based on real restaurant P&L data, most operators overestimate this effect by 40-60%.
? Example:
Regular salmon sales: 12 portions weekly
- During 25% off promotion: 18 portions (+6 extra)
- Loss on all 18 portions: 18 × €5.16 = €92.88
- Profit from 6 additional portions: 6 × €8.28 = €49.68
Net weekly loss: €43.20
Track substitution damage
This hidden cost kills promotion profitability. Customers who'd normally order your €32 ribeye now grab the discounted salmon instead.
? Example:
Customer switches from ribeye (€29.36 excl. VAT) to promotional salmon
- Ribeye margin: €20.80
- Promotional salmon margin: €8.28
Additional loss per switch: €12.52
Decision matrix for your promotions
Categorize each promotion based on your calculations:
- Keep running: Generates net positive cash flow
- Modify terms: Small losses but significant volume increases
- Kill immediately: Costs money with minimal traffic boost
⚠️ Watch out:
Happy hour on drinks CAN work (low ingredient costs), but on food often doesn't (high food cost).
Smart alternatives to margin-killing discounts
Try these tactics that feel valuable but cost less:
- Free appetizers: €2 cost feels like €8 value to guests
- Wine upgrades: House to premium for same price
- Fixed-price menus: Three courses for €35
- Punch cards: Buy 9 meals, get the 10th free
Track these metrics religiously
Monitor promotion performance with specific data points:
- Units sold: promotional period vs. baseline weeks
- Total revenue: promotional period vs. baseline weeks
- Average ticket size during promotion
- New customer percentage vs. repeat visitors
Food cost software helps you run these calculations quickly and spot which promotions actually drive profits versus those that just drive traffic.
How do you calculate if a promotion is profitable? (step by step)
Calculate loss per item
Subtract the promotion price from the normal price. This is your direct loss per sold item during the promotion. Always calculate excl. VAT.
Estimate extra volume
How much more sales do you get during the promotion? Look at previous promotions or test for one week. Multiply extra volume by your normal margin per item.
Add up and draw conclusion
Loss per item × total volume - profit on extra volume = net effect. Is this positive? Keep it. Negative? Cut it or adjust it.
✨ Pro tip
Track your promotion performance for exactly 14 days, comparing against the same two-week period from last month. Calculate both volume changes and average check differences - many 'successful' promotions actually reduce your per-customer revenue.
Calculate this yourself?
In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.
Calculate it yourself?
Our free food cost calculator does it in seconds.
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Frequently asked questions
How do I know if my happy hour is profitable?
Should I include VAT in my promotion calculations?
What if I can't estimate how many extra customers a promotion brings?
Are 2-for-1 deals always money losers?
How do I stop customers from only ordering promotional items?
What's better - percentage discounts or free add-ons?
How often should I review my promotion profitability?
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
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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