Prime Day Inventory Planning for Amazon FBA Sellers | Inventory Hero
·5 min readForecasting
Prime Day Inventory Planning for Amazon FBA Sellers
Prime Day inventory planning: forecast the deal spike, order a full lead time early, cover the event without overbuying, and plan the post-event drawdown.
Enough to cover the event window at the uplifted deal velocity, plus your normal baseline for the surrounding days, without running out mid-event. Estimate the uplift from a past deal on a comparable SKU (a 3x to 5x velocity bump over the deal window is common but varies widely), and stage the reserve so you are not overcommitted if the lift is smaller than hoped.
When should I order Prime Day inventory?
A full lead time before the event. A July Prime Day with an 80-day total lead time means ordering in spring. Deal inventory that lands late misses the event entirely, and Amazon's deal submission deadlines and inventory checks happen weeks ahead, so late stock can also disqualify you from the deal.
Andrew Erickson is the founder of Inventory Hero. He has spent years working with Amazon FBA sellers on demand forecasting, restock planning, and the cash flow side of running a private-label brand. Inventory Hero exists because every spreadsheet-based inventory system he tried eventually broke — usually right before Q4.
Plan the drawdown before the event. After the spike, demand falls back to baseline, so any deal stock you overbought sells slowly and risks aging. Size the deal order to the event plus a modest tail, hold reserve outside FBA where possible, and ease the price down after the event rather than carrying a pile of slow-moving units.
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Prime Day inventory planning means forecasting the deal spike as a separate event, ordering a full lead time before it, covering the event window at the uplifted velocity without overbuying, and planning the post-event drawdown. The short version: a deal can multiply a SKU's sales for the event but does nothing for your baseline, so you plan it on its own and keep the spike out of your everyday forecast. Below is how to size the deal, when to order, and how to land the aftermath.
A deal lifts velocity for the event window, sometimes dramatically. Plan the event cover on that uplifted rate, not normal velocity:
Estimate the uplift. The best source is your own past deal on the same or a comparable SKU: pull unit sales during that deal window from your Seller Central Promotions dashboard or the Advertising console. As a rough anchor, a Lightning Deal on a mid-priced item often runs about 3x to 4x normal velocity for its short window, and a deeper or longer discount can push higher, but it varies enough by category and discount depth that your own history beats any rule of thumb.
Cover the window at the uplifted rate. If a SKU sells 15 a day normally and you expect a 4x lift over a two-day event, that is roughly 15 x 4 x 2 = 120 units for the event itself, on top of the normal baseline for the surrounding days.
Add a modest tail, not a mountain. Demand falls back after the event, so size to the event plus a small tail rather than a big post-event reserve you will struggle to move.
This is the same separate-the-event discipline you apply to any promotion in inventory forecasting: forecast the baseline, add the event lift on top, and keep them distinct.
Prime Day has two clocks, and the earlier one is not the event. Order a full lead time before the event itself (a July Prime Day on an 80-day lead time means ordering in spring), but the real constraint is often the deal submission window:
Deal submission and inventory checks. Amazon's deal deadlines and the inventory verification that goes with them happen weeks before the event, and they check that you have enough committed stock. Land your inventory late and you do not just arrive late, you can be disqualified from the deal entirely.
Check-in before a high-traffic window. Units have to be checked in and sellable before the event, and check-in is variable and slower near peak, so build buffer into the arrival date rather than cutting it to the event day.
Back the order date out from the event through your full lead time in the reorder point calculator, and place it early rather than cut it close.
Because the deal stock is a bet on an uplift estimate, do not commit all of it to FBA early. Hold the reserve at a 3PL or in AWD and push it into FBA close to the event, so a smaller-than-hoped lift does not leave you with a fulfillment center full of slow units paying storage.1
Then plan the drawdown. After the spike, demand returns to baseline, so any deal stock you overbought sells at the normal rate, which can mean months of cover appearing overnight. A seasonal or event SKU should exit the event near its normal stocking level, not carry an event-sized pile. Ease the price down after the event if you are long, rather than letting the surplus age.
Prime Day inventory planning is event forecasting: estimate the uplift from past deals, cover the window at the uplifted rate, order a full lead time ahead of both the event and the deal deadlines, stage the reserve outside FBA, and plan the drawdown to baseline. Keep the spike separate from your run rate, and the event lifts sales without wrecking the months around it. For the wider system, see how to forecast Q4 inventory and Amazon inventory forecasting.