Methodology
How this calculator estimates your losses
The estimate combines 4 factors: a sector loss rate (1.4% to 3.4% of revenue per IHL Group, NRF Shrink Survey and INSEE benchmarks), a multiplier for your current system (paper x1.6, Excel x1.0, dedicated software x0.45), an inventory frequency factor (monthly 0.7, quarterly 1.0, annual 1.4) and an SKU factor (more references, more error). The result is intentionally cautious: most retail consultancies estimate real losses are 1.2× to 2× higher than this calculation.
Shrinkage
Known vs unknown shrinkage: the killer of margins
"Known" shrinkage covers what you identify: documented breakage, marked expiry, supplier returns. "Unknown" shrinkage is what disappears without trace — internal theft, external theft, undetected receiving errors, mislabelling, missed entries. Per the NRF, unknown shrinkage represents 60-70% of total retail losses — and that is exactly what mobile scan tools reduce by forcing traceability of every movement.
Multiplier effect
Why 1% of inventory error costs 8% of margin
On an average 35% gross margin, a 1% inventory error of revenue equals 1/35 = 2.9% of margin. But this misses two cascading effects: lost sales from phantom stockouts (the system thinks stock is there, customer leaves), and defensive overstocking that locks cash. Combined, McKinsey Retail Insights shows 1% of inventory error actually erodes 5-8% of annual gross margin. That is what makes "it’s only 50 €" estimates misleading.
Dormant stock
The hidden cost of stock that sleeps in your warehouse
Beyond breakage, theft and expiry, there is stock that does not move. Every square metre costs (rent, insurance, handling), and every euro tied up has an opportunity cost (you could have invested elsewhere). Rule of thumb: 25% annual cost on every euro of immobilised stock. With 20,000 € of dormant stock > 6 months, you burn 5,000 €/year invisibly. Our [dormant stock calculator](outils/calculateur-stock-dormant) quantifies this line precisely.
Case studies
Three concrete numerical examples
80-cover restaurant (35,000 €/month revenue): estimated losses ~1,200 €/month, dominated by fridge expiry and morning count errors. Fashion retail (50,000 €/month, 400 SKUs): ~1,100 €/month, dominated by unknown shrinkage and size errors. Shopify e-commerce (80,000 €/month, 700 SKUs): ~1,800 €/month, dominated by phantom stockouts and picking errors. In all three cases, a 15 €/month mobile tool pays for itself before the end of month 1.
When to switch
When a calculator is not enough
This calculator gives an order of magnitude. Going further requires a real field diagnostic: audit of inventory variances over 12 months, observation of one receiving day, store-staff interviews. Most consultants charge 1,500 to 3,000 € for this. Free alternative: take an ApsionScan trial, scan for 2 weeks, compare theoretical vs actual quantity — you have your real unknown shrinkage.
Without digital tracking vs with ApsionScan (SMB 50k€/mo)
| — | Excel + paper | ApsionScan mobile |
|---|
| Estimated monthly losses | €1,100 | ~€500 |
| Inventory hours / month | 8 h | 2 h |
| Stockout detection delay | 2-5 days | Real time |
| Tool monthly cost | €0 | €15 |
| Net annual ROI | — | +€6,900 |
How-to
Use the diagnostic in 4 steps
A typical workflow to produce a numbered diagnostic in 5 minutes, ready to present to your team or accountant.
- 1
Fill in your numbers
Monthly revenue, sector, gross margin, SKU count, inventory frequency and current system.
- 2
Read the breakdown
The donut chart breaks losses by source: waste, stockouts, data entry errors, expiry.
- 3
Download the PDF
The PDF diagnostic shows your inputs, annualised number, breakdown and recommendation.
- 4
Share internally
Use "Copy link" to send your diagnostic to a partner without them re-entering numbers.