Most restaurants track sales religiously but ignore their daily purchases. Smart operators know these two numbers must align—if you're selling €500 daily but only purchasing €150 in ingredients, you're either running down inventory or missing receipts. Both scenarios cost money.
The 20-30% rule as a starting point
Here's your baseline: daily purchases should hover around 20-30% of daily sales. Drift far outside this range? Time to investigate.
💡 Example:
Yesterday's sales hit €800. Your purchases:
- Meat: €85
- Fish: €65
- Vegetables: €45
- Other: €35
Total purchases: €230 = 28.7% of €800
Solid numbers for most restaurants.
What do deviations mean?
From years of working in professional kitchens, I've seen these patterns emerge repeatedly:
- Much higher (40%+): You've overbought, suppliers hiked prices, or sales dropped unexpectedly
- Much lower (15% or less): Running on fumes from last week's inventory, or receipts are going missing
- Wild swings: Zero planning, or you're dealing with seasonal ingredient costs
⚠️ Watch out:
This check breaks down on big delivery days. Stock up for the entire week on Monday? That day's ratio will look terrible.
Weekly check is more reliable
Want accuracy? Think in weeks, not days:
💡 Example weekly check:
Week 1 totals:
- Total sales: €4,200
- Total purchases: €1,260
Percentage: €1,260 / €4,200 = 30%
Right in the sweet spot.
Signals to watch for
These patterns in your daily tracking tell a story:
- Creeping upward: Purchase percentage climbs each week → suppliers are raising prices
- Roller coaster: Monday 15%, Tuesday 45% → your ordering needs work
- Consistently high: Multiple weeks above 35% → menu pricing or portion control issues
What do you do with the result?
Think of this check as your early warning system. Consistently hitting 35% or higher? Here's your action plan:
- Calculate food costs on your top 5 sellers
- Review recent supplier invoices for price increases
- Audit portion sizes—is your kitchen being too generous?
- Track waste for three days—what's hitting the trash?
Tools like KitchenNmbrs can automate these calculations, but a simple spreadsheet works too.
✨ Pro tip:
Check your purchase-to-sales ratio every morning at 9 AM using yesterday's final numbers. Takes 90 seconds and catches problems before they compound.
How do you do the daily purchase check? (step by step)
Write down yesterday's sales and purchases
Get your cash receipt (sales) and all purchase receipts from yesterday. Add up the purchases. Don't forget small receipts.
Calculate the percentage
Divide total purchases by sales and multiply by 100. For example: €240 purchases / €800 sales × 100 = 30%.
Check if it's normal
Between 20-35% is usually normal for restaurants. Much higher or lower? Write this down and figure out why.
✨ Pro tip
Check your purchase-to-sales ratio every morning at 9 AM using yesterday's final numbers. Takes 90 seconds and catches problems before they compound.
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
What if I buy for the whole week on Monday?
The daily check becomes meaningless on delivery days. Switch to weekly tracking: total all purchases and sales over 7 days for an accurate picture.
Is 35% purchases always problematic?
Not necessarily. Fine dining restaurants often run higher due to premium ingredients, while pizza places typically run lower. Focus on trends—is your percentage climbing month over month?
Should I include beverages in this calculation?
Skip the beverages and focus purely on food ingredients. Drinks operate on different margins and will skew your kitchen performance data.
What if I don't have all my purchase receipts?
This system falls apart without complete records. Start collecting every receipt immediately—even the €10 emergency herb run affects your ratios.
My ratio varies wildly between weekdays and weekends—is this normal?
Absolutely. Weekend sales might spike while purchases stay steady, creating lower ratios. Track patterns over full weeks to smooth out these natural fluctuations.
How do I account for inventory I already had on hand?
This check assumes you're using roughly what you buy each day. For precision, do monthly inventory counts and adjust your food cost calculations accordingly.
What's considered a 'red flag' percentage that demands immediate attention?
Anything above 40% for three consecutive days, or below 10% for a full week. Both extremes signal serious issues with purchasing, pricing, or record-keeping.
📚 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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