How to Navigate Amazon’s Low-Inventory Fee for FBA

Running lean on Amazon inventory used to be a smart cash flow strategy. Now it triggers fees that eat directly into your margins.

Amazon's low-inventory-level fee charges FBA sellers up to $1.11 per unit when stock falls below 28 days of supply. For high-volume sellers, that adds up to hundreds or thousands in unexpected costs each month.

The challenge now is building an inventory system that keeps you above the threshold without tying up excess capital in storage.

In this guide, you will learn how the fee works, who pays it, and how to protect your profits.

Understanding the Amazon low-inventory fee in 2026

Amazon's low-inventory-level fee charges FBA sellers who maintain less than 28 days of inventory for standard-size products. The fee applies per unit shipped and ranges from $0.32 to $1.11 depending on product size and how far below the threshold your stock falls.

The fee triggers when both your 30-day and 90-day historical days of supply drop below 28 days.

Amazon calculates "days of supply" by dividing your average daily inventory units by your average daily shipped units. If both averages fall below 28 days, you pay the fee on every unit shipped while under threshold.

Here is a clear breakdown:

Table 1: Amazon low-inventory fee breakdown by product type

For example, if you sell 1,000 units per month of a large standard product (up to 3 lb) and your days of supply drops to 18 days, you pay $0.70 per unit. That adds $700 in fees for the month.

By comparison, stocking an additional 300 units to stay above 28 days might cost $261 in monthly storage (at $0.87 per cubic foot). The difference: $439 in avoidable fees by running lean.

You can check your historical days of supply in Seller Central under Inventory > FBA Inventory. The column displays the greater of your 30-day and 90-day metrics. If both fall below 28 days, the fee applies.

Suggested read: How to Manage Amazon Inventory for Better Profits

How Amazon’s 2026 changes break traditional inventory models

Old inventory models focused on minimizing storage costs, but Amazon’s new fee penalizes understocking. This forces sellers to balance ecommerce cash flow, buy box eligibility, and new cost structures.

The fee was introduced to drive faster Amazon inventory turnover and fulfillment efficiency. When sellers run lean, Amazon’s network faces shipping bottlenecks, increased operational costs, and risks to Prime delivery promises.

By requiring sellers to maintain at least 28 days of supply, Amazon reduces its own costs and improves customer experience.

For sellers, this shift means:

• Buy box risk: Stockouts can cause loss of buy box and sales to competitors
• Margin erosion: Unexpected per-unit fees eat directly into profits
• Cash flow pressure: More inventory means more capital tied up in stock

These contradictory pressures force sellers to abandon traditional inventory strategies entirely. But not every seller faces the same risks.

Suggested read: Maximize Amazon Profit for Sellers' Margins in 2026

Amazon low-inventory fee impact analysis

Fee exposure depends on your selling model: arbitrage, wholesale, and private label each face unique challenges.

Arbitrage sellers: Lower risk, but watch for patterns

Arbitrage sellers typically operate with sporadic, low-volume inventory. Most one-off or clearance buys do not maintain a steady enough flow to trigger the fee. However, risk emerges when restocking repeatable SKUs or seasonal products.

Example: Restocking 500 units of a seasonal SKU for off-peak months triggers $0.50 per unit x 500 = $250 per month in fees if inventory drops below the threshold before the next restock arrives.

Real-time dashboards let arbitrage sellers track SKU-level supply and fee exposure automatically.

Suggested read: 5 Tips for Keeping Inventory Accurate in Real Time

Wholesale sellers: Compounding risk across catalogs

Wholesale sellers manage high SKU counts and steady volume. The risk compounds across the catalog, as each SKU is now assessed separately at the FNSKU level.

Example: Managing 100 SKUs, each with 20 units below threshold, results in $0.40 per unit x 2,000 units = $800 per month in fees.

Automated inventory management tools help wholesale sellers monitor dozens of SKUs and surface fee risks before they erode margins.

Private label sellers: Margin erosion risk

Private label sellers rely heavily on FBA and are sensitive to margin changes. Buffer stock is essential, but tying up capital in inventory can strain cash flow.

Example: Carrying 5,000 units per month, with 10 days under threshold, triggers $1.00 per unit x 5,000 = $5,000 in fees.

Integrated platforms like Webgility let private label sellers forecast ecommerce demand, automate restocks, and protect margins at scale.

Once you know your risk, the next step is deciding if you pay the fee or increase your inventory.

Decision framework: Pay the Amazon low-inventory fee or increase inventory?

Choosing between paying the Amazon low-inventory fee or increasing inventory is a numbers game. Here is how to decide for every SKU.

Use this matrix to compare the true cost of the fee vs. the cost of holding more inventory:

Table 2: Decision matrix for paying Amazon’s low-inventory fee

Smart sellers use real-time data to make these decisions fast and reliably. Making these calculations across dozens of SKUs is only possible with the right tools. Here is an analysis.

Suggested read: 6 Amazon Accounting Problems for Sellers & Accountants

5 tactics to cut your Amazon low-inventory fee exposure

The right tactics keep your inventory above Amazon’s low-inventory fee threshold and your margins intact:

1. Set automated inventory alerts for days-of-supply thresholds.
2. Use demand forecasting to time restocks accurately.
3. Sync inventory across all channels to avoid accidental understock.
4. Review fee exposure weekly using a dashboard or report.
5. Reconcile Amazon fees with your accounting to spot margin leaks.

Manual tracking vs. automated systems: A cost-benefit analysis

Manual spreadsheets cannot keep up with Amazon’s dynamic fee triggers. Integrated platforms make real-time, SKU-level decisions possible.

Manual tracking:

• Time-consuming and error-prone
• Lagging data increases the risk of missed fees
• Difficult to scale beyond a handful of SKUs

Standalone inventory tools:

• Partial view; often lacks accounting sync
• May not track Amazon fee triggers in real time

Integrated platforms:

• Real-time inventory updates across Amazon, Shopify, and other channels
• Automated accounting sync for accurate financials
• SKU-level profitability and fee exposure reporting

Webgility connects Amazon, Shopify, and accounting in real time, giving sellers the data to make confident, margin-protecting decisions.

So instead of reacting to fees after they hit, you can monitor inventory levels proactively and adjust replenishment before crossing the 28-day threshold.

Schedule a demo with Webgility today.

Frequently asked questions (FAQs)

How do I avoid triggering Amazon’s low-inventory fee?

Maintain at least 28 days of inventory supply based on both 30-day and 90-day averages for each FNSKU. Use automated alerts and real-time dashboards to monitor inventory levels and restock before falling below the threshold.

Does the fee apply to all product categories?

No. Some categories, like apparel and shoes, are exempt. New products within their first 180 days and items with insufficient sales history are also excluded from the low-inventory fee.

What’s the best way to track inventory days of supply?

Use integrated inventory management platforms that calculate days of supply automatically using real-time sales and stock data. Manual tracking is error-prone and not scalable for multiple SKUs.

How can I minimize the impact of the low-inventory fee on my margins?

Forecast demand accurately, set up automated inventory sync, and review fee exposure regularly. Compare the cost of holding extra inventory to the potential fee and adjust your strategy for each SKU.