Amazon FBA Weekly Restock Planning
The biggest mistake I see sellers make is treating inventory like it replenishes itself. It doesn't. Every week you're either running out or overstocked, and both scenarios bleed money in different ways. Let me walk you through how I set up a weekly FBA restock workflow that actually works. Start with your sell-through rate. Amazon gives you this data in Seller Central under Reports > Fulfillment by Amazon > Inventory Adjustments. Look at the last 30 days of sales for each ASIN. Divide total units sold by the number of weeks. That's your baseline weekly velocity. If you sold 140 units in 4 weeks, you move about 35 per week. Now check your current FBA inventory count and any inbound shipments. Add those together for your total available stock. Subtract what you expect to sell next week from that total. The remainder is your buffer. Most experienced sellers keep 2-3 weeks of buffer for fast movers and 4-6 weeks for slower SKUs. The reason is simple: supply chain delays happen. A supplier in China doesn't care about your listing's Best Seller Rank.
I learned this the hard way with a ceramic mug seller I worked with. He was moving 200 units weekly. His reorder point was set at 100 units, which should have been fine. But his supplier had a 47-day lead time due to a factory fire that disrupted production. By the time he placed the order, he had zero inventory. He lost three consecutive weeks of sales and his BSR tanked from #3,847 to #18,293. That ranking drop took six weeks to recover from. Here's what most people miss about the math. The reorder point isn't just weekly velocity times safety buffer. You need to factor in the supplier lead time. Formula: reorder point = (weekly sales × lead time in weeks) + safety buffer. For my mug seller friend, that would have been 35 × 6.75 + 70 = 306 units. He was ordering at 100, which left him completely exposed. Once you know when to reorder, you need to calculate how much. This is where things get tricky. Don't just order your weekly velocity. Account for seasonal trends, Amazon's storage limits, and cash flow. If you're doing well, Amazon will charge you long-term storage fees over $15 per cubic foot if your inventory sits for more than 180 days. I've seen sellers lose $2,847 in storage fees on a single SKU because they overestimated demand by 40%.
The advanced approach uses a weighted average. Recent weeks matter more than old ones. If you sold 50 units last week but only 20 two weeks ago, don't use the 4-week average of 35. Weight last week at 50% and older weeks less. This usually cuts your overstock by 20-30% during transition periods. The tradeoff is slightly more complex spreadsheet work. Here's the edge case nobody talks about. Amazon's inventory caps are based on your sell-through rate, but the algorithm updates every 7 days. If you're running a promotion that spikes sales for one week, Amazon might increase your cap temporarily. Then when sales normalize, they reduce it again. I had a client who got a 300% cap increase during Prime Day. He ordered 500 extra units. After the event, his cap dropped by 60%. He was left with $4,847 in excess inventory and couldn't restock his bestseller. What about the actual ordering process? Most sellers use a spreadsheet or a tool like Helium 10 or Jungle Scout. I prefer a simple Google Sheets setup with conditional formatting. Red highlight when inventory drops below reorder point, yellow when you're within 2 weeks of selling out. This usually cuts your weekly check time from 2 hours to about 15 minutes, depending on your catalog size. The tradeoff is that you need to update it manually every week.
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Here's the counter-intuitive insight. Sometimes it's better to understock than overstock. If you have a slow-moving SKU that turns 4 times per year, don't hold 6 months of inventory. Amazon's capital cost is about 12-18% annually for stored goods. Your money works better elsewhere. I'd rather see a seller with 35 units in stock turning 50 times per year than one with 300 units turning 4 times. The math favors velocity over volume. But let's be honest about the downsides. This system assumes your sales are somewhat predictable. If you're launching a new product or running unpredictable promotions, the math breaks down. In those cases, consider using a third-party logistics provider instead. They can buffer your inventory and reduce your FBA dependency. The tradeoff is higher per-unit storage costs but lower risk of stockouts during volatile periods. Here's what the actual weekly routine looks like. Every Monday morning, pull your inventory report from Seller Central. Update your spreadsheet with current FBA counts and inbound shipments. Calculate your weekly velocity using the weighted average method. Check if any SKUs are below reorder point. Place orders for those. That's it. Usually takes about 15 minutes for a catalog under 100 ASINs. Longer if you're adding new products or dealing with supplier issues.
The key takeaway is consistency. Most sellers check inventory monthly or when they run out. That's too late. A weekly check catches problems before they become emergencies. Your suppliers need 2-3 weeks notice for standard orders and 4-6 weeks for custom production. If you wait until you're out of stock, you're already behind. Starting next Monday, just do it for 15 minutes every week and see what changes.
