Catch invoice line-price drift before it eats your margin
Compare each invoice line against expected unit prices and act on real variances, not noise.
Your oil costs €4.50/L in your records. This week's invoice bills it at €4.86 — an 8% jump nobody noticed because the case total looked normal next to the meat order. Multiply that pattern across twenty staples and several weeks: this is how kitchens lose two points of food cost without a single dramatic event. Line-price variance checking exists to make each of those small moves visible on the day it happens.
Setting up variance checks that survive busy service
- Start from normalized units. Variance only means something when both prices are per the same cookable unit.
- Pick thresholds by impact. Alert at 5% on top-20 lines; ignore 2% wobble on condiments.
- Record who follows up. A flagged variance without an owner becomes wallpaper within a week.
- Re-baseline deliberately. When you accept a new market price, update the expected price consciously — never let it drift silently.
A worked example
Expected prices from last month's baseline: oil €4.50/L, chicken breast €7.90/kg, flour €0.62/kg. Three invoices arrive.
| Oil | billed €4.86 / L | +8.0% |
|---|---|---|
| Chicken | €7.92 / kg | +0.3% |
| Flour | €0.68 / kg | +9.7% |
Oil is up 8.0% and flour is up 9.7% on the stated per-unit basis; both exceed the 5% alert threshold. Verify the pack, specification and agreed price before requesting a correction. Chicken is up 0.3% and stays below the threshold.
Interactive example · price spread
Spread between your highest and lowest quoted unit price: €6.30 (€39.90 → €46.20). Compare the quoted prices with each supplier. This is a price difference, not a savings projection.
Running the loop
- 1Enter invoices with pack configs intact. Unit prices compute correctly only if case composition is recorded alongside totals.
- 2Review the variance list daily in under five minutes. Three flagged lines is a manageable conversation; thirty unread ones are a guilt pile.
- 3Challenge with normalized numbers. Suppliers respond to specifics: 'you billed €4.86/L against our agreed €4.50' lands very differently than 'prices went up'.
- 4Escalate patterns, not incidents. One bad week is weather. The same line drifting three weeks running is a pricing change you haven't agreed to.
FAQ
- Isn't this just reading invoices carefully?
- Reading catches what eyes notice. Variance checking compares every line against a stored expectation — including the boring middle-of-invoice lines where most drift hides.
- What threshold should I set?
- Tight enough to matter, loose enough to avoid crying wolf: 5% on major lines works for most kitchens. Tighten to 3% once the habit holds.
- How does this relate to pack normalization?
- They're partners. Normalization makes prices comparable; variance checking makes them watched. Without normalization, every pack change reads as a false alarm — and false alarms kill the practice.
- Can I automate the follow-up?
- Partially: software can flag, log, and even draft the supplier email. The negotiation itself still needs a human who knows the relationship.
Keep reading
- Normalize pack sizes so your numbers tell the truth
Convert cases, formats and units to a common basis before comparing prices or costs.
- Compare prices across the suppliers you already use
A fair comparison framework for recurring restaurant products and current suppliers.
- Score your suppliers on more than price
A simple scorecard for restaurant suppliers: fill rate, substitutions, accuracy and price stability alongside cost.
Browse by category
Want to review your purchasing?
Submit the details and we will confirm which invoices are useful.
Review 3 invoices free