Your fries cost more than you think — and that's eating into your profits. Most restaurant owners estimate fries costs but miss cutting loss, oil consumption, and energy expenses. Here's how to calculate your true cost per portion from potato purchase price.
Gather all costs for one portion of fries
Fries aren't just potatoes. You've got oil, energy, and peeling loss to account for. Every cent adds up to your real cost price.
💡 Example costs per portion of fries (150g):
- Potatoes: €0.32
- Frying oil: €0.18
- Energy (gas/electricity): €0.08
- Salt, seasonings: €0.02
Total cost price: €0.60 per portion
Calculate the cutting loss of potatoes
Potatoes shrink during prep. Peeling removes skin, you cut out eyes and bad spots. This loss bumps up your actual kilo price beyond your purchase price. Always work with the weight after processing.
⚠️ Note:
Don't skip cutting loss calculations. From 1 kg of raw potatoes you'll end up with 800-850 grams after peeling and cutting.
The formula for actual kilo price: Purchase price / (Yield percentage / 100)
💡 Calculation example cutting loss:
Potatoes cost €1.20 per kilo. After peeling you've got 820 grams usable.
- Yield: 82%
- Actual kilo price: €1.20 / 0.82 = €1.46 per kilo
- For 150g portion: €1.46 x 0.15 = €0.22
Add frying oil and energy costs
Oil and energy are the hidden killers of your fries margin. Most operators forget these completely. The oil needs regular replacement and fryers consume serious electricity or gas. These costs represent 20-30% of your total fries expense.
- Frying oil: Average €0.15-0.20 per portion (varies by oil type)
- Energy: Around €0.06-0.10 per portion (fryer at 180°C)
- Seasonings/salt: Roughly €0.01-0.03 per portion
Check your food cost percentage
A healthy food cost for fries runs 20-28% of your selling price. Go higher and you're basically giving away this side dish. Based on real restaurant P&L data, operators who track fries costs monthly see 15% better margins on sides overall.
💡 Food cost calculation:
Cost price fries: €0.60 per portion. Selling price: €2.75 incl. 9% VAT
- Selling price excl. VAT: €2.75 / 1.09 = €2.52
- Food cost: (€0.60 / €2.52) x 100 = 23.8%
This hits the sweet spot for fries as a side dish.
Track price fluctuations
Potato prices swing wildly by season and harvest quality. Check your purchase prices monthly minimum and update your calculations. Spring hits especially hard — potatoes can jump 40% or more.
Tools like a food cost calculator automate these calculations and show your cost per portion instantly, so you don't have to recalculate manually every time prices shift.
How do you calculate the cost price of fries per portion?
Determine the weight per portion and cutting loss
Weigh a standard portion of fries (usually 150-200 grams). Measure how much you have left from 1 kilo of raw potatoes after peeling and cutting. Use this yield for the actual kilo price.
Calculate the actual potato costs per portion
Divide your purchase price per kilo by the yield percentage. Multiply this by the weight of your portion. Example: €1.20 / 0.82 x 0.15 kg = €0.22 per portion.
Add frying oil, energy, and seasonings
Calculate on average €0.18 for frying oil, €0.08 for energy, and €0.02 for salt/seasonings per portion. These amounts can vary by location and energy contract.
Check your food cost percentage
Divide your total cost price by your selling price excl. VAT and multiply by 100. A healthy food cost for fries is between 20-28% of your selling price.
✨ Pro tip
Weigh exactly 20 portions of fries over the next week and calculate your true average portion size. Most kitchens guess at 150g but actually serve 170-180g — that extra 25g per portion can kill your margin.
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 much cutting loss do potatoes have on average?
Potatoes lose 15-20% on average from peeling, eyes, and bad spots. From 1 kilo of raw potatoes you'll have roughly 800-850 grams of usable product left.
Should I include VAT in my cost price calculation for fries?
No, always calculate with the selling price excluding VAT. Fries carry 9% VAT, so divide your menu price by 1.09 to get the price excl. VAT for your food cost calculation.
What is a healthy food cost for fries?
A healthy food cost for fries runs 20-28% of your selling price excl. VAT. As a side dish this can run slightly higher than main courses since you don't need the same margin on it.
📚 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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