Running out of stock kills your Amazon ranking. Holding too much inventory drains your cash and triggers long-term storage fees. The sweet spot between these two problems is called your reorder point, and most beginner sellers guess at it instead of calculating it.
If you've ever stared at your Seller Central dashboard wondering when to send your next shipment, this guide is for you. Mastering reorder point calculation inventory management is one of the highest-ROI skills you can build as an Amazon seller. It protects your Best Seller Rank, prevents stockouts, and keeps Amazon from charging you aged inventory surcharges.
In this article, you'll learn the exact reorder point formula, how to find each number you need, how to apply it to FBA, and the most common mistakes beginners make. By the end, you'll be able to plan your next purchase order with confidence.
Before you source your first product, make sure you have the fundamentals locked in. This free checklist is used by hundreds of Bubba Academy students to launch faster and avoid costly rookie mistakes.
A reorder point is the inventory level that signals it's time to place a new order with your supplier. When your stock hits this number, you reorder, not before, not after. Done correctly, your new shipment arrives just as your current stock runs low.
For Amazon sellers, this matters more than for almost any other business model. Here's why:
A proper reorder point gives you a data-driven trigger instead of relying on gut feeling. It removes emotion from your purchasing decisions and lets you scale without constantly putting out fires.
The basic reorder point calculation inventory management formula is simple:
Reorder Point = (Average Daily Sales × Lead Time in Days) + Safety Stock
Let's break this down with a quick example. Say you sell 20 units per day, your supplier lead time (including shipping and FBA check-in) is 45 days, and your safety stock is 200 units.
Reorder Point = (20 × 45) + 200 = 1,100 units
When your available inventory hits 1,100 units, place your next order. This ensures product arrives before you run out, even if there are minor delays.
The formula works for both private label and wholesale sellers. The only thing that changes between products is the inputs. The math stays the same. Build a simple spreadsheet with each SKU listed, and you can update your reorder points weekly in under 10 minutes.
Plugging in bad numbers gives you bad results. Here's how to find each variable correctly:
Pull your last 30 to 60 days of sales data from Seller Central under Reports > Business Reports > Detail Page Sales and Traffic by Child Item. Divide total units sold by the number of days. If your product is seasonal, weight recent months more heavily or use a year-over-year comparison.
This is the total time from placing the PO to your product being live in FBA. Include:
Always use the worst-case lead time you've experienced, not the best case.
Safety stock is your buffer against demand spikes and delays. A simple formula:
Safety Stock = (Max Daily Sales × Max Lead Time) − (Average Daily Sales × Average Lead Time)
If you don't have enough data, use 2–4 weeks of average sales as a starting buffer.
You now know the theory. It's time to build something real. Bubba Academy's step-by-step program takes you from zero to your first sale on Amazon — even if you've never sold anything online before.
FBA adds complexity that other selling models don't have. Your reorder point calculation needs to account for it.
1. Track "available" inventory, not total inventory.
Amazon's available stock excludes reserved units, units in transfer, and unfulfillable units. Use this number as your trigger, not the total on hand.
2. Account for inbound shipments.
If you already have a shipment in transit, subtract its arrival timeline from your reorder calculation. Don't double-order.
3. Watch your IPI score and storage limits.
A low Inventory Performance Index can cap how much you can send in. If your reorder quantity exceeds your storage limit, you'll need to space out shipments or improve your IPI first.
4. Plan around Q4 and Prime Day.
Sales can spike 2–5x during peak periods. Adjust your average daily sales input upward 60–90 days before these events, or you'll stock out at the worst possible time.
5. Avoid long-term storage fees.
Reorder too aggressively and you'll have units sitting past 181 days. Aim for 60–90 days of forward cover, not 180+.
Even with the formula in hand, beginners trip up in predictable ways. Avoid these:
A simple way to stay on top of these mistakes is to review your top 10 SKUs every Monday. Update sales velocity, check inbound shipments, and confirm your reorder points still make sense.
You don't need expensive software to manage this, but the right tools save hours.
Free options: - Google Sheets or Excel: Build a simple tracker with columns for SKU, daily sales, lead time, safety stock, reorder point, and current stock. Use conditional formatting to flag SKUs that hit their reorder point. - Seller Central Restock Inventory Report: Amazon offers built-in restock suggestions, though they're often too conservative. Use them as a sanity check, not the final answer.
Paid options: - Inventory management tools like SoStocked, Forecastly, or Sellerboard automate the reorder point calculation inventory management process across all your SKUs and factor in seasonality. - ERP systems like Skubana or Linnworks make sense once you're managing 50+ SKUs or selling on multiple channels.
Start with a spreadsheet. Graduate to software when manual tracking takes more than 30 minutes per week. The goal isn't fancy tools, it's a reliable system that prevents both stockouts and long-term storage fees.
Reorder points aren't optional once you're serious about selling on Amazon. The formula is straightforward: (Average Daily Sales × Lead Time) + Safety Stock. Get the inputs right, recalculate monthly, and you'll avoid the two biggest inventory mistakes that sink new sellers, stocking out and overstocking.
The key takeaways:
Your next step: Open a spreadsheet today, list your top 5 SKUs, and calculate the reorder point for each one. Once you see the numbers, you'll never go back to guessing.
You've learned the concepts. Now build the business. Bubba Academy gives you a complete step-by-step roadmap — from finding your first product to your first profitable sale on Amazon.
Reorder point calculation in inventory management is the formula that tells you exactly when to place a new purchase order before you run out of stock. The basic formula is: (Average Daily Sales × Lead Time in Days) + Safety Stock. For Amazon sellers, this prevents stockouts and helps avoid long-term storage fees from overordering.
Amazon sellers avoid long-term storage fees by keeping inventory levels lean and ordering only what they can sell within 6 to 12 months. Using a reorder point formula helps you time purchases so stock arrives just before you sell out, instead of sitting in FBA warehouses. Regularly reviewing slow-moving SKUs and creating removal orders also prevents aged inventory charges.
As a beginner, aim for 2 to 4 weeks of safety stock, depending on how reliable your supplier and shipping times are. If your lead time varies a lot, lean toward 4 weeks; if it's consistent, 2 weeks is enough. Too much safety stock ties up cash and triggers long-term storage fees.
Reorder point calculation inventory management is important for FBA sellers because Amazon charges aged inventory surcharges after 181 days and long-term storage fees after 365 days. Calculating your reorder point keeps stock flowing at the right pace, protects your Inventory Performance Index (IPI) score, and prevents both stockouts and overstock losses.
You should recalculate your reorder point at least once a month, or anytime your sales velocity, supplier lead time, or seasonality changes. Q4 holiday season, new product launches, and PPC scaling can all shift your daily sales numbers fast. Reviewing monthly keeps your inventory decisions accurate and avoids costly storage fees.