Amazon introduced the low-inventory fee to encourage sellers to maintain enough stock to meet demand. If your inventory levels drop below a threshold relative to recent sales, Amazon adds a surcharge to your fulfillment fee.
This fee is the most commonly missed cost in FBA profit calculations. Most free calculators skip it entirely.
How It Works
The low-inventory fee applies when your inventory level (in units) is below a threshold that Amazon calculates based on your product's recent sales velocity. The threshold is typically set to cover 14 days of historical sales.
If you ship 10 units per day and have 50 units in stock, you have 5 days of cover. Amazon's threshold is 14 days. You'll be charged the low-inventory fee until you restock.
How Much Does It Cost?
The fee varies by size tier:
| Size Tier | Low-Inventory Fee (per unit) |
|---|---|
| Standard (under 1 lb) | $0.12 – $0.35 |
| Standard (1–2 lb) | $0.20 – $0.50 |
| Large (2–5 lb) | $0.35 – $0.80 |
| Large (5+ lb) | $0.50 – $1.20 |
On a product with a $10.62 net profit per unit (our earlier example), a $0.35 low-inventory fee cuts margin by 3.3%. On thin-margin products, it can eliminate profit entirely.
When It Hurts Most
- Seasonal products — demand spikes, stock runs low faster
- New launches — limited historical data, Amazon uses conservative estimates
- Slow restocking — if your supplier has long lead times
- Lean inventory strategy — the fee penalizes the JIT approach
How to Avoid It
- Maintain 14+ days of cover based on trailing 30-day sales
- Use Amazon's restock report to forecast when you'll dip below threshold
- Ship smaller, more frequent batches instead of large infrequent shipments
- Factor it into your sourcing — if your margin is under 15%, the fee eats into it significantly
Calculate Your Real Net
Our FBA Calculator includes the low-inventory fee by default, along with all six other FBA fees. Enter your price, COGS, category, and size tier to see the true net profit per unit.