Incorrect input in your system leads to incorrect numbers, and incorrect numbers lead to wrong decisions. Many restaurant owners make costly mistakes because they don't realize that one wrong price or quantity entered can ruin their entire food cost calculation. In this article, you'll learn which input errors have the biggest impact and how to prevent them.
The cascade of incorrect input
One wrong number has a domino effect. If you enter the price of beef incorrectly, all dishes with beef are wrong. If you set the portion size incorrectly, your food cost calculation is useless. The problem: you often don't notice until it's too late.
💡 Example:
You enter salmon at €18/kg, but your supplier charges €22/kg.
- Calculated food cost: €4.50 per portion
- Actual food cost: €5.50 per portion
- Difference: €1.00 per portion
With 50 salmon dishes per week, you lose €2,600 per year
The 5 biggest input errors
These mistakes cost the most money:
- Wrong purchase prices: Old prices that haven't been updated
- Wrong portion sizes: 200g entered, but chef gives 250g
- Forgotten ingredients: Oil, butter, herbs not included in calculation
- Wrong units: Per piece vs per kilo mixed up
- Cutting loss not included: Whole fish vs fillet price
⚠️ Watch out:
A 5% difference in food cost can cost €10,000+ per year for an average restaurant. Check your input regularly.
How incorrect input affects your decisions
With wrong numbers, you make wrong decisions:
- Menu price too low: You think you have 28% food cost, but it's actually 35%
- Promoting the wrong dishes: You push the 'profitable' dish that's actually losing money
- Planning purchases wrong: Too much of expensive ingredients, too little of cheap ones
- Directing your team wrong: Chef gets targets that are impossible because of incorrect numbers
💡 Example:
Restaurant thinks their steak has 32% food cost and puts it as a 'special' on the menu.
- Actual food cost due to incorrect input: 38%
- Extra loss per steak: €1.80
- With 20 extra sales from promotion: €36 loss
They're promoting their loss leader without knowing it
Why this happens in practice
Many entrepreneurs make these mistakes because:
- No time: Updating prices takes time you don't have
- No system: Recipes in heads or on scraps of paper, not centralized
- No control: Nobody checks if the entered numbers are correct
- No awareness: Not realizing that small errors have big consequences
The solution: one system, one truth
With a system like KitchenNmbrs, you prevent these errors:
- Central ingredient database: One price per ingredient, used everywhere
- Automatic calculation: Change one price, all recipes update automatically
- Control signals: Food cost above 35%? The system warns you
- Mobile input: Update prices from your car after visiting the supplier
⚠️ Watch out:
A system is only as good as the input. Even with the best app, you need to make sure you enter the correct numbers.
The difference with Excel or notebooks
Separate systems increase the risk of errors:
- Excel: Formulas can break, numbers get scattered across multiple files
- Notebooks: Old prices are forgotten, nobody knows what's current
- Memory: Chef 'knows roughly' what things cost - usually wrong
💡 Example:
Restaurant with Excel system:
- Beef price in 3 different files
- File A: €28/kg (current)
- File B: €24/kg (3 months old)
- File C: €26/kg (unknown when)
Which one is correct? Nobody knows for sure
Start with your top 5 dishes
You don't need to get everything perfect at once. Start with your 5 best-selling dishes:
- Check all ingredient prices with your supplier
- Weigh the actual portions your chef gives
- Include everything: also oil, butter, garnish
- Update your system with the correct numbers
- Calculate the new food cost
Once these 5 dishes are correct, you've already solved 80% of your problem. You can tackle the rest step by step.
How do you prevent input errors? (step by step)
Check your supplier invoices weekly
Compare the prices on your invoices with the prices in your system. Suppliers regularly raise prices without big announcements. Update immediately if you see differences.
Weigh your actual portions
Have your chef make 5 portions of your top dishes and weigh them. Use the average as your standard portion size. Repeat this every 3 months.
Make one person responsible
Assign one team member to do all price updates. Give this person access to your system and make it part of their tasks. This prevents updates from being forgotten.
✨ Pro tip
Check your 3 best-selling dishes every month by recalculating them with current prices. This takes 15 minutes but can save thousands of euros per year.
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
How often should I update my ingredient prices?
Check your invoices weekly and update immediately if prices change. Suppliers can adjust prices monthly, especially for meat and fish.
What if my chef gives different portions than entered?
Weigh the actual portions regularly and adjust your system. A difference of 20 grams of meat can cost €0.50+ per portion.
Can't I just add a 10% margin for errors?
A margin helps, but doesn't solve the problem. You want to know what your actual costs are, not guess with a buffer.
How do I prevent forgetting ingredients in my calculation?
Make a checklist: main ingredient, vegetables, sauce, oil, herbs, garnish. Go through each dish systematically.
What if different team members enter different prices?
Make one person responsible for all price updates. Don't give others access to change prices, only to view the numbers.
📚 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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