📝 Purchasing, suppliers & strategy · ⏱️ 2 min read

How do I calculate the purchase price per portion for an ingredient that gets repriced quarterly?

📝 KitchenNmbrs · updated 13 Mar 2026

Quarterly price reviews of purchase prices make cost calculations tricky. Your chef is calculating with old prices while suppliers have already become 10% more expensive. In this article you'll learn how to set up a system to always work with current prices.

Why quarterly prices disrupt your cost price

Many suppliers review their prices every 3 months. Meat, fish and vegetables fluctuate the most. The problem: your recipes and cost prices stay the same, while your purchasing becomes more expensive.

💡 Example:

Your steak recipe from January:

  • Entrecote 250g: €6.25 (€25/kg)
  • Garnish: €2.10
  • Total ingredients: €8.35

April price review: entrecote becomes €29/kg

New cost price: €9.35 (+€1.00 per portion)

With 50 steaks per week you lose €2,600 per year if you don't update.

The 3-price system for stable cost prices

Work with three prices per ingredient to absorb fluctuations:

  • Current price: what you pay now
  • Average price: average of last 4 quarters
  • Worst-case price: highest price from past year + 10%

For cost price calculation use the worst-case price. Then you're always safe.

💡 Example salmon:

Price progression over the past year:

  • Q1: €22/kg
  • Q2: €26/kg
  • Q3: €24/kg
  • Q4: €28/kg

Average: €25/kg

Worst-case for cost price: €30.80/kg (€28 + 10%)

Automatic price update routine

Set up a system that checks your prices every month:

  • Week 1 of every month: check invoices from previous month
  • Note deviations: which products are 5%+ more or less expensive?
  • Update cost prices: adjust recipes with new prices
  • Check menu: do selling prices need to go up too?

⚠️ Note:

Never update all prices at once. Choose your 3 most expensive ingredients and start there. This keeps it manageable.

Seasonal compensation in your cost price

Some products are predictably more expensive in certain months. Build a buffer for that:

  • Asparagus: out of season 200-300% more expensive
  • Shellfish: Christmas/New Year 30-50% more expensive
  • Lamb: around Easter 20-40% more expensive

Calculate with peak season prices for your cost price, even if you buy it cheaper.

💡 Example asparagus season:

Dutch asparagus cost price:

  • April-June (season): €8/kg
  • Rest of year: €24/kg

Always calculate with €24/kg in your cost price

During season you make extra margin, outside season you're covered

Digital vs manual tracking

Manual price lists in Excel quickly become outdated. With 50+ ingredients it becomes unmanageable. Many entrepreneurs use an app like KitchenNmbrs to maintain prices centrally and have cost prices recalculated automatically.

The advantage: change one ingredient price, and all recipes with that ingredient are automatically updated. This way you immediately see which dishes become more expensive and whether you need to adjust your menu prices.

How do you calculate purchase price per portion with quarterly price reviews?

1

Collect price history per ingredient

Go through your invoices from the last 12 months. Note the price per kg/liter for each main ingredient per quarter. Focus first on your 10 most expensive ingredients.

2

Calculate worst-case price per ingredient

Take the highest price from the past year and add 10% to it. This becomes your calculation price for cost price calculations. This way you're always on the safe side.

3

Update cost price per recipe

Recalculate the cost price of each dish with the new worst-case prices. Divide the total ingredient costs by your selling price excl. VAT for your food cost percentage.

4

Check your food cost and menu prices

If your food cost comes above 35%, you need to raise your menu price or adjust your recipe. Calculate your new minimum price: cost price divided by desired food cost.

5

Set up monthly check routine

Schedule 30 minutes every first week of the month to check invoices for price changes. Immediately update your cost prices if an ingredient changes 5% or more.

✨ Pro tip

Check your 3 best-selling dishes every month on food cost. If those are under control, you have 70% of your profitability under control.

Calculate this yourself?

In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.

Try KitchenNmbrs free →

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Frequently asked questions

How often should I update my cost prices?

Check your invoices monthly for price changes of 5% or more. Update your cost prices immediately then. For smaller changes you can wait until the quarter is over.

Should I track all ingredients or only the main ones?

Start with your 10 most expensive ingredients that make up 80% of your food cost together. Spices and small ingredients fluctuate less and have less impact on your total cost price.

What if my supplier doesn't have fixed quarterly dates?

Create your own monthly overview and group by 3 months. It's about the trend, not exact quarter dates. The important thing is that you notice price fluctuations.

How do I prevent becoming too expensive by using worst-case prices?

Calculate with worst-case for cost price, but buy smart. During cheap periods you make extra margin. You need that buffer for expensive periods.

Can I make contract agreements to limit price fluctuations?

Large suppliers sometimes offer fixed prices for 6-12 months for a small premium. For small businesses this rarely pays off because you lose flexibility with other suppliers.

ℹ️ This article was prepared based on official sources and professional expertise. While we strive for current and accurate information, the content may differ from the most recent regulations. Always consult the official authorities for binding standards.

📚 Sources consulted

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.

JS

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.

🏆 8 years kitchen manager at 1NUL8 Group Rotterdam
Expertise: food cost management HACCP kitchen management restaurant operations food safety compliance

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