Many chefs think converting package prices to per-kilo costs is just basic math, but there are hidden traps that can throw off your entire food cost calculation. Understanding net vs gross weight, seasonal variations, and supplier packaging changes makes the difference between accurate costing and budget surprises. Without proper conversion, you're essentially cooking blind.
Why the kilo price matters
Your supplier invoices €24 for a box of tomatoes. But what does a kilo actually cost? And how much tomato do you need for 100 portions of pasta? Without the kilo price, you can't calculate an accurate cost price.
The difference can be significant:
- Box A: 5 kg for €25 = €5.00/kg
- Box B: 8 kg for €32 = €4.00/kg
Box B seems more expensive, but it's actually 20% cheaper per kilo.
💡 Example:
You buy salmon by crate from your fish supplier:
- Price per crate: €180
- Weight per crate: 12 kg
- Calculation: €180 ÷ 12 kg = €15.00/kg
Kilo price: €15.00
Different packaging types
Each supplier has their own system. The most common ones are:
- Box/carton: Vegetables, fruit, meat
- Crate: Fish, poultry, some vegetables
- Bag: Potatoes, onions, flour
- Can/jar: Canned goods, sauces
- Bottle: Oil, vinegar, syrups
The basic formula
The same formula applies to every package:
Kilo price = Packaging price ÷ Weight in kg
💡 Example beef:
Vacuum packed steak:
- Price: €85 per package
- Weight: 3.2 kg
- Calculation: €85 ÷ 3.2 kg = €26.56/kg
This is your purchase price for cost calculation
Converting grams to kilograms
Some suppliers list weight in grams. Divide by 1000 to get kilograms:
- 2500 grams = 2500 ÷ 1000 = 2.5 kg
- 750 grams = 750 ÷ 1000 = 0.75 kg
- 1800 grams = 1800 ÷ 1000 = 1.8 kg
⚠️ Note:
Always check whether the listed weight is net (without packaging) or gross (with packaging). For cost calculation you need the net weight.
Liquid products
For liquids like oil, milk or wine, you convert per liter to per kilogram. For most liquids: 1 liter ≈ 1 kg.
💡 Example olive oil:
Jerrycan of olive oil:
- Price: €45 per jerrycan
- Contents: 5 liters
- Calculation: €45 ÷ 5 liters = €9.00/liter
For cost calculation: €9.00/kg
Practical tips for purchasing
Create an overview of all your suppliers with their packaging sizes. Update this regularly, as suppliers sometimes change their packaging.
From tracking this across dozens of restaurants, I've seen that suppliers often adjust package sizes without warning - especially during seasonal transitions. Keep this information digital for easy updates.
- Check monthly whether prices have changed
- Watch for seasonal variations in vegetables and fruit
- Compare different suppliers on kilo price, not packaging price
💡 Comparison example:
Two suppliers for chicken breast:
- Supplier A: €32 for 4 kg = €8.00/kg
- Supplier B: €45 for 6 kg = €7.50/kg
Supplier B is cheaper, despite higher packaging price
How do you calculate the kilo price? (step by step)
Note the packaging price and weight
Check the invoice or ask your supplier for the exact price per package and the net weight. Make sure you have the weight without packaging.
Convert weight to kilograms
If the weight is in grams, divide by 1000. For liquids in liters you can usually use 1 liter = 1 kg.
Divide packaging price by weight
Use the formula: Kilo price = Packaging price ÷ Weight in kg. This gives you the purchase price per kilogram for your cost calculation.
✨ Pro tip
Weigh 3 sample packages from each supplier within the first 48 hours of delivery to catch packaging inconsistencies early. This simple check can reveal up to 15% weight variations that throw off your food costs.
Calculate this yourself?
In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.
Was this article helpful?
Frequently asked questions
Should I include VAT in the kilo price calculation?
No, for cost calculation you always use the purchase price excluding VAT. You can reclaim the VAT from the tax authority.
What if my supplier has different packaging sizes?
Calculate the kilo price separately for each packaging size. Often the largest package is cheapest per kilogram, but not always.
How often should I update my kilo prices?
Check at least once a month whether suppliers have changed their prices. For seasonal products like vegetables this may need to be done more frequently.
Can I have this calculated automatically?
Yes, in food cost management systems you enter the packaging price and weight, after which the kilo price is calculated automatically and used in your recipes.
What if the weight per package varies?
Take the average weight from the last 5-10 deliveries. Or ask your supplier to agree on a standard package weight.
How do I handle mixed packaging like herb bundles or portion packs?
Weigh the actual usable product after removing ties, rubber bands, or individual wrapping. Count the portions and divide total package price by usable weight for accurate costing.
📚 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.
Optimize your purchasing with data
Know exactly which supplier is most cost-effective and how price changes affect your margins. KitchenNmbrs links purchasing directly to recipe costs. Try it free for 14 days.
Start free trial →