Inventory Planner
Forecast your inventory needs, track stock levels across warehouses, set replenishment targets, and prevent stockouts, all from a single view.
Difficulty: 🟡 Intermediate · Reading time: ~15 min
Open this page in your dashboard: Go to Inventory Planner →
📋 Overview
The Inventory Planner page helps you stay ahead of stockouts and overstocking. It combines real-time stock levels, sales velocity calculations, and demand forecasting to tell you exactly how much inventory to send, and when. Whether you sell via FBA or FBM, across one marketplace or ten, this tool keeps your supply chain healthy.
Why this matters: Stockouts cost more than just lost sales. Amazon penalizes your organic ranking, your PPC spend is wasted, and competitors capture your Buy Box. A single week out of stock on a top seller can take 2-4 weeks of recovery to regain your previous ranking position.
📊 Key Performance Indicators
Total Products
Number of tracked products
Restock Required
Products that need replenishment now
Out of Stock
Products with zero available units
Healthy Inventory
Products within target stock levels
Total Units
Combined units across all products and warehouses
Quick win: If your "Restock Required" number is greater than zero, address those products first. Sort the table by "Days Left" ascending to prioritize the most urgent items.
Inventory Table
For your first week: Focus on just 4 columns : Current Stock, Daily Sales Avg, Days Left, and Status. These tell you what needs restocking now. The remaining columns become useful as you scale.
A complete, 14-column interactive table with full sorting, search, and pagination:
Product
Product name, image, SKU (Stock Keeping Unit), ASIN (Amazon Standard Identification Number), FNSKU
Current Stock
Units currently available in Amazon warehouses
Inbound
Units in transit to Amazon (shipped but not yet received)
Reserved
Units reserved for pending orders or processing
Pending Transfers
Units being transferred between fulfillment centers
Daily Sales Avg
Average units sold per day (based on lookback period)
Expected Sales
Projected units to sell during target replenishment period
Days Left
Estimated days until current stock runs out
Units to Send
Recommended replenishment quantity
Status
Color-coded badge (see below)
Stock Bar
Segmented visual bar showing inventory composition
Expected OOS (Out of Stock) Date
Projected out-of-stock date
Status Badges
Critical
Red
Stock will run out within days
Low
Orange
Stock below target, reorder soon
Healthy
Green
Stock within target range
Overstocked
Blue
More stock than needed for the target period
No Sales
Gray
Product has no recent sales data
Out of Stock
Dark Red
Zero units available
Stock Bar Visualization
Each product row includes a segmented bar showing:
Green: Current available stock
Blue: Inbound units
Purple: Reserved units
Orange: Units to send (replenishment needed)
👣 Step-by-Step Example: Calculating a Reorder
Here is a realistic scenario showing how SellerMagnet calculates reorder recommendations:
Scenario: You sell a garlic press (ASIN: B09EXAMPLE1) on Amazon.de. Your supplier is based in Shenzhen, China.
Current Stock
120 units
Inbound
0 units
Daily Sales Avg (30-day lookback)
8 units/day
Supplier Lead Time
21 days (production)
Shipping to Amazon FBA
14 days (sea freight + customs)
Safety Buffer
7 days
Total Target Days
42 days
SellerMagnet's calculation:
Expected Sales during target period: 8 units/day x 42 days = 336 units
Current Stock + Inbound: 120 + 0 = 120 units
Units to Send: 336 - 120 = 216 units
Days Left at current rate: 120 / 8 = 15 days (Status: Critical)
Expected OOS Date: 15 days from today
Action required: In this example, you have only 15 days of stock but your total replenishment cycle is 42 days. You need to place an emergency order immediately, or consider air freight to bridge the gap.
Reorder Calculation Template
Use this template to configure your Target Days slider for each product category:
Supplier Production Time
___ days
Time from PO to goods ready
Shipping to Amazon
___ days
Transit + customs + FBA check-in
Safety Buffer
___ days
Extra cushion (7-14 days recommended)
Total Target Days
___ days
Set your slider to this value
Best practice: Create a spreadsheet with these values for each supplier. Your Target Days should reflect your slowest supplier if you cannot filter by product group.
🔍 Filters
Marketplace
All Marketplaces, or select specific
All
Lookback Days
7, 14, 30, 90 days (for velocity calculation)
30 days
Fulfillment Type
FBA, FBM
FBA
Condition
New, Used, Refurbished, Collectible, etc.
All
Target Days (slider)
1-180 days (replenishment target)
60 days
Hide Fully Stocked
Checkbox
Off
Hide Zero Units to Send
Checkbox
Off
Pro tip: Use a 7-day lookback during fast-moving periods (Prime Day, Black Friday) to capture spikes. Switch back to 30 days during normal periods for a more stable average.
Choosing the Right Lookback Period
7 days
Capturing recent trends, during promotions
Overreaction to one-off spikes
14 days
Balanced short-term view
May still reflect temporary promotions
30 days
Stable average, most sellers' default
May lag behind seasonal shifts
90 days
Long-term trending, slow-moving inventory
Ignores recent sales velocity changes
EFN (Pan-European) Mode
If you use Amazon's European Fulfillment Network (EFN), the tool automatically aggregates inventory for the same ASIN across EU marketplaces (DE, FR, IT, ES, NL, SE, PL, BE). Stock levels use the maximum values (shared pool), while sales velocity is summed across all participating marketplaces.
EFN (European Fulfillment Network) mode ensures your forecasting accounts for the shared inventory pool, preventing duplicate reorder recommendations.
Pan-European sellers: If you recently switched from EFN to Pan-EU (where Amazon distributes stock across multiple country warehouses), your inventory data will shift. Allow 2-3 days for SellerMagnet to recalibrate stock positions after a fulfillment network change.
Per-Product Forecast Chart
Click the chart icon on any product row to view a detailed stock forecast for that individual product:
Historical stock levels
Projected depletion timeline
Recommended reorder point
Expected out-of-stock date
Actions
Search
Filter by product name, SKU, ASIN, or FNSKU
Column Toggle
Show/hide columns to customize your view
Export
Download as CSV or PDF
Print-optimized view (UI elements removed)
Refresh
Manual data reload
🔄 Before & After: Impact of Using Inventory Management
Stockout frequency
3-5 products/month
0-1 products/month
Overstock (excess units)
40% of catalog
Under 10% of catalog
Manual spreadsheet time
4-6 hours/week
0 hours (automated)
Revenue lost to stockouts
~8-12% monthly
Under 2% monthly
Storage fee waste
High (overstocked SKUs)
Minimal
ROI example: A seller doing EUR 50,000/month who reduces stockout-related revenue loss from 10% to 2% recovers EUR 4,000/month, that is EUR 48,000/year in revenue that would have otherwise been lost.
Seasonal & Timing Advice
Q4 preparation (September-October): Increase your Target Days slider by 50-100% starting in September. Supplier lead times stretch during peak season, and Amazon's FBA receiving windows become slower. If your normal target is 45 days, consider setting it to 70-90 days for Q4 SKUs.
Post-holiday (January-February): After the holiday rush, switch your lookback to 90 days temporarily. A 7- or 14-day lookback in early January will show artificially low sales velocity and cause you to under-order for February/March recovery.
Prime Day (typically July): Two weeks before Prime Day, switch to a 7-day lookback for any products included in Lightning Deals or promotions. Revert to 30 days one week after the event.
⚠️ Common Mistakes to Avoid
Mistake 1: Using a lookback period that is too short during product launches. New products with only 7 days of sales history will have unreliable velocity calculations. Wait until you have at least 14-30 days of data before relying on automated reorder recommendations.
Mistake 2: Ignoring inbound shipments in your calculations. If you have 200 units inbound and the tool shows 200 "Units to Send," you do not need to send 200 more. The inbound column already factors into the recommendation, but double-check that your inbound shipment is actually moving (not stuck at "Checked In" for weeks).
Mistake 3: Setting the same Target Days for all products. A product sourced from a local warehouse (3-day lead time) and a product from overseas (45-day lead time) should not share the same Target Days. Use the slider as a global default, but review individual SKUs that deviate from your typical supply chain.
Mistake 4: Not accounting for Amazon's receiving delays. During Q4 or after major sale events, Amazon warehouses can take 1-3 weeks to check in your inventory. Factor this into your Target Days. Your goods are not sellable until they appear as "Available."
Mistake 5: Overstocking slow-moving SKUs. Just because a product is "Low" does not mean you should send 6 months of stock. For slow sellers (under 1 unit/day), overstocking triggers long-term storage fees. Keep target days conservative for these items.
## 🔧 Troubleshooting
Why is my inventory not syncing?
Check your Amazon SP-API (Selling Partner API) connection. Navigate to Settings > Connections and verify your Amazon marketplace shows a green "Connected" status.
Verify the correct marketplace is selected. If you are filtering by Amazon.de but your inventory is on Amazon.com, you will see no data.
Allow time after initial setup. First-time syncs can take 15-60 minutes depending on catalog size. Look for the "Last Synced" timestamp at the bottom of the page.
Check Amazon Seller Central. If Seller Central itself is showing delayed data (common during peak periods), SellerMagnet will reflect the same delays.
Why does "Units to Send" show zero for a product I know needs restocking?
Your inbound shipments may already cover the expected demand. Check the "Inbound" column.
The "Hide Zero Units to Send" filter may be off but the lookback period might show low sales. Try switching from 30 to 14 days.
The product might have zero sales in the lookback period, resulting in a "No Sales" status.
Why is my Daily Sales Avg different from what I see in Seller Central?
SellerMagnet calculates the average using the lookback period you selected. Seller Central may use a different time window. Additionally, SellerMagnet excludes days when you were completely out of stock from the velocity calculation (to avoid deflating the average).
My forecast chart shows a sudden drop: what happened?
A sudden drop usually indicates either: (a) a bulk order or promotion that spiked sales, (b) a shipment that was received and then quickly sold, or (c) an inventory adjustment by Amazon (removed or transferred units). Check your Reimbursements page for any lost/damaged inventory events around that date.
❓ FAQ
Does SellerMagnet account for out-of-stock days when calculating sales velocity?
Yes. Days when your product had zero available stock are excluded from the Daily Sales Avg calculation. This prevents the average from being artificially deflated by stockout periods and gives you a more accurate reorder quantity.
Can I set different Target Days for different products?
The Target Days slider applies globally to all products in the current view. For product-level customization, use the per-product forecast chart to manually assess individual SKUs with different lead times.
How often does inventory data refresh?
Inventory data syncs automatically every 2-4 hours via the Amazon SP-API. You can trigger a manual refresh at any time using the Refresh button.
Does this work for FBM (Merchant Fulfilled) products?
Yes. Switch the Fulfillment Type filter to FBM. For FBM products, "Current Stock" reflects the inventory count you have reported to Amazon. Sales velocity and forecasting work the same way.
What happens if I sell on multiple EU marketplaces with EFN?
SellerMagnet automatically detects EFN enrollment and aggregates your inventory. You will see one consolidated row per ASIN instead of separate rows per marketplace, with combined sales velocity across all EU marketplaces.
Can I export the data to share with my supplier?
Yes. Click Export and choose CSV or PDF. The export includes all visible columns, so use the Column Toggle to include or exclude fields before exporting. Many sellers send the CSV directly to their supplier with the "Units to Send" column highlighted.
Why does the Expected OOS Date keep changing?
The Expected OOS Date is recalculated on every data sync based on your current stock level and the most recent sales velocity. If your sales speed up (e.g., a competitor goes out of stock), the OOS date moves closer. If sales slow down, it moves further out.
💡 Tips
Pro tip: Set your Target Days slider to match your supplier lead time + shipping time. For example, if your supplier needs 15 days to produce and 10 days to ship to Amazon, set the target to 30-40 days (with buffer).
Filters are saved between sessions via local storage, so your preferred view persists when you return.
Pro tip: Export your inventory report every Monday morning and compare it to the previous week. Look for any product that shifted from "Healthy" to "Low", those are your priority reorders for the week.
Pro tip: If you run Lightning Deals or Coupons, temporarily reduce your lookback to 7 days for the week after the promotion ends. This helps you see whether the elevated sales velocity is sustainable or a one-time spike.
➡️ What's Next?
Fee AuditReimbursements (Lost & Found)Last updated