Prime Big Deal Days 2026 (Oct 6–7): The Seller Countdown to Amazon's Oct 15 Peak Fees

It is 1:00 p.m. Pacific on Tuesday, October 6. Amazon has just released the third batch of deals for the day, and your phone case is in it. (This is a made-up store, but the drop times are Amazon's.) Over the next hour the case sells 40 units on Amazon. Your Shopify store only hears about Amazon sales once an hour, so for that hour it keeps offering cases that are already gone.

That hour sits inside a tight two weeks. Amazon's announcement of Prime Big Deal Days 2026 confirms the October Prime Day runs October 6–7: 48 hours, starting 12:01 a.m. PT on October 6, in 22 countries. Eight days after it ends, on October 15, Amazon's 2026 holiday peak fulfillment fees start and stay until January 14, 2027.

This post walks through October 1 to October 15 one day at a time. It shows how many units to hold back from your other channels during the event, which Amazon fee a sales spike can set off, and when to ship restock for Black Friday and Cyber Monday (BFCM, the late-November sales weekend) before the higher rates begin.

What is locked in, and what you still control

Start with the uncomfortable part. Amazon moved the deadline for submitting Prime Big Deal Days deals once, and Amazon's Seller Central notice extending the deal window to September 22 covered Best Deals, Lightning Deals, Prime Exclusive Discounts and coupons. That date has passed.

The same notice told sellers to get their Fulfillment by Amazon (FBA) stock in before each event's cutoff. FBA means Amazon stores your units and ships them for you. The inbound dates were not extended. If Amazon has not already received your units at a warehouse, they will not sell during the event. Anything on a truck right now is BFCM stock.

Shoppers will see the event like this:

• Three deal drops a day, at midnight, 8 a.m. and 1 p.m. PT, across more than 35 categories.
• Alexa for Shopping price history of up to 365 days, plus deal alerts and auto-buy at a target price. Shoppers can see whether your "deal" is lower than your usual price. Some orders will fire on their own the moment a price drops below a shopper's target. We covered what that means for listings in our breakdown of Amazon's auto-buy and price-tracking features.

One useful rule from the same Amazon notice: Prime Big Deal Days promotional prices are excluded from the 30-day and 60-day lookback window used for Black Friday and Cyber Monday deal pricing. That window is the price history Amazon checks to decide whether a deal is a discount. A deep October price will not raise the bar for your November deal.

The day-by-day countdown: Oct 1 to Oct 15

A few terms in the table: "days of supply" is how many days your stock will last at the rate it is selling. FBM (fulfilled by merchant) means you ship Amazon orders yourself, and DTC (direct to consumer) means your own website. A buffer is a number of units you hide from a channel so it cannot sell stock that has just sold somewhere else.

Two dates just past the window matter too. Amazon's Holiday 2026 announcement of fees and inbound deadlines sets BFCM arrival targets of October 21 for FBA with minimal shipment splits and October 28 for Amazon-optimized splits. BFCM deal submissions close October 20. The recovery week is when all three get decided.

The Oct 15 fee change, with real numbers

Amazon says the 2026 holiday peak fee adds about $0.32 per unit, on average, to its normal fee for picking, packing and shipping an order. That is the same average increase as last year. It applies to FBA and to three related services: Remote Fulfillment with FBA (FBA stock shipped to buyers in Canada and Mexico), Multi-Channel Fulfillment or MCF (Amazon ships orders from your other sales channels out of your FBA stock) and Buy with Prime (Prime checkout on your own website). Amazon's examples, reported by Supply Chain Dive, are below. The size tier is Amazon's size-and-weight band for a product, and it sets the fee.

Then add the surcharge. Amazon's notice of the 3.5% fuel and logistics surcharge put it on FBA fees from April 17, 2026, and on MCF and Buy with Prime from May 2. It is calculated on your fulfillment fee, not your sale price, and Amazon described it as temporary with no end date. Amazon's holiday notice lists it alongside the peak fee, and it is charged on top.

Worked example: one small-standard SKU, before and after Oct 15

Example: a phone case in the small-standard tier, with the same $2.49 base fee as Amazon's example, selling 3,000 units between October 15 and January 14. In plain English: take the fee, add 3.5% of it, and compare the event week with the peak season.

Before Oct 15 (event week)
  Base fulfillment fee            $2.49
  + 3.5% surcharge (2.49 x 0.035) $0.087
  = All-in per unit               $2.577  (~$2.58)

From Oct 15 to Jan 14
  Peak fulfillment fee            $2.68
  + 3.5% surcharge (2.68 x 0.035) $0.094
  = All-in per unit               $2.774  (~$2.77)

Difference per unit               $0.197
x 3,000 peak-season units         $590 in extra fulfillment cost

Twenty cents looks small until you set it against margin. Say the SKU nets $1.50 per unit after ads through the season: the peak fee and surcharge together take about 13% of that profit.

Two practical consequences:

• The event is cheaper to fulfill than anything after it. Units sold October 6–7 ship at non-peak rates. That is an argument for pushing sell-through on slow SKUs now rather than dragging them into Q4.
• MCF gets more expensive for your other channels too. If Amazon fulfills your Shopify, Walmart or TikTok Shop orders through MCF, those orders pay peak rates plus the surcharge from October 15. Compare that with shipping them yourself or through a 3PL (a third-party warehouse that stores and ships for you).

A product a fraction of an inch over a tier boundary pays the higher tier's peak fee all season. Check your dimensions in the FBA size tier explorer, and see our full 2026 FBA fee breakdown for storage rates and every other line item.

Storage moves too. October through December is Amazon's peak monthly storage period, billed at a much higher per-cubic-foot rate than the rest of the year. Every unit you send "just in case" now costs peak storage until it sells.

The low-inventory-fee trap after a deal spike

Amazon charges the low-inventory-level fee when your stock would last fewer than 28 days at your recent sales rate. Amazon calls this "historical days of supply." Amazon's explainer on how the low-inventory-level fee is calculated says it looks at a short-term (last 30 days) and a long-term (last 90 days) view, and charges only if both are under 28 days. Three groups are exempt: new sellers in their first year, new-to-FBA products enrolled in FBA New Selection, and products that AWD refills automatically.

A deal spike hits the fee from both sides. Sales go up, so each unit covers fewer days. Stock goes down, so there is less left to cover them.

Worked example: days-of-supply math

Say a SKU normally sells 20 units a day. You have 700 units at Amazon on October 1, which is 35 days of cover and well above the line. You expect the deal to sell 150 units a day for two days. In plain English: divide the stock you have left by your average daily sales over 30 days, then over 90 days, and see if both land under 28.

Oct 1-5: 5 days x 20       = 100 sold  ->  600 on hand
Oct 6-7: 2 days x 150      = 300 sold  ->  300 on hand

Short-term view (last 30 days, simplified)
  sales = 28 x 20 + 300    = 860 units -> 28.7/day
  days of supply = 300 / 28.7        = 10.5 days   (< 28)

Long-term view (last 90 days, simplified)
  sales = 88 x 20 + 300    = 2,060 units -> 22.9/day
  days of supply = 300 / 22.9        = 13.1 days   (< 28)

Both under 28 -> the fee can apply on units shipped until you recover.

This is simplified, because Amazon's exact measure also depends on what it counts as available and inbound. The direction is right, though. To stay above 28 days on the short-term view after the event, you would need roughly 28.7 × 28 ≈ 800 units at Amazon, or about 500 more than you will have.

You probably can't ship 500 units in by October 8. What you can do:

• Book restock shipments to Amazon before the event, so they are already moving when the spike hits.
• Cut ad spend on thin-stock SKUs once projected days of supply goes under 28, so you are not paying for sales that also earn you a fee.
• Accept the fee on purpose on SKUs where the deal margin clearly covers it. Put it in your margin math and move on.

Our guide to avoiding the low-inventory-level fee has the 2026 fee bands and the exemptions in detail.

Don't let a Prime deal oversell Shopify, Walmart and TikTok Shop

If you sell the same SKU on Amazon and elsewhere from one pool of stock, the event is a 48-hour test of your inventory sync, meaning how fast a sale on one channel lowers the stock count on the others. The common setups fail in different ways:

The buffer formula

Deals drop at fixed times, so orders arrive in bursts rather than an even stream. Size buffers to the burst, not the daily average. In plain English: hold back as many units as a channel could sell before it finds out the stock is gone.

Buffer per channel = peak orders per hour x sync delay (hours)

Example: 40 units/hour at the 8 a.m. PT drop, 15-minute sync
  40 x 0.25 = 10 units minimum buffer

Same burst, 60-minute sync (hourly CSV/feed updates)
  40 x 1.0  = 40 units minimum buffer

Then add a reserve on top: the units you are deliberately holding for your own site and other marketplaces. If your Shopify store runs its own counter-offer that week, it needs guaranteed stock, not whatever Amazon leaves behind.

The faster your sync, the smaller the buffer. With a 15-minute delay, the example above needs 10 units held back; with hourly updates it needs 40. Nventory keeps Amazon, Shopify, Walmart and TikTok Shop on one stock count and updates each of them in under five seconds. On slower sync, keep the bigger buffers and accept that some units will sit unsold. For the full method, see the step-by-step system for never overselling, and use the safety stock calculator to set reorder buffers for the weeks after.

Ad budget pacing for three daily drops

With new deals at midnight, 8 a.m. and 1 p.m. PT, a daily budget that burns out by mid-morning misses the afternoon drop entirely. Pace for all three.

• Split each day into three windows and check spend against plan after each drop. If 70% of the budget is gone before 1 p.m. PT, raise it or cut bids on low-converting terms.
• Tie ads to stock as well as ROAS (return on ad spend, the sales each ad dollar brings back). A campaign that converts well on a SKU heading below 28 days of supply is buying a fee and a stockout. Pause it at a stock threshold you set in advance.
• Don't shut off on Oct 8. Shoppers who set price alerts or auto-buy targets keep buying after the event if your price stays close. Taper budgets over two or three days and watch conversion before cutting.
• Protect the SKUs you need for BFCM. If your best Black Friday SKU can't be restocked in time, spend on a different one now.

Assign one person per drop to watch stock and spend together. The 30-minute inventory war room checklist is a good template for those check-ins.

If you are weighing BFCM deals next, factor in the deal fee Amazon's holiday notice lists: a $100 upfront fee per promotion plus 1.5% of promotional sales, capped at $5,000.

Oct 8–14: returns, reimbursements, restock

Returns

Returns from October 6–7 orders will arrive over the following weeks, right as you're trying to count stock for BFCM. Track which returned units come back sellable, and don't count customer-damaged units as available on other channels until they are inspected.

Reimbursement checks

High-volume weeks produce lost and damaged inventory claims, units received short and refunds without a matching return. Pick a date two to three weeks after the event to check your FBA stock against orders and returns. Our guide to Amazon's 2026 reimbursement rules covers what's claimable and the time limits.

Restock before capacity tightens

FBA caps how much stock you can send each month, a figure Amazon calls your capacity limit. Amazon's explanation of how monthly FBA capacity limits work says next month's limit is announced in the third full week of each month, with estimates for the two months after, and that your IPI influences the estimate. IPI, the Inventory Performance Index, is Amazon's score for how well you manage stock. That puts November's limit around October 18–24. You can bid for extra space through Capacity Manager, where performance credits can offset up to 100% of the reservation fee if the units sell through.

The order of operations for the recovery week:

1. Recalculate days of supply for every deal SKU on October 8 using actual event sales.
2. Book FBA shipments immediately for anything you need sellable for BFCM, against Amazon's October 21 and October 28 arrival targets.
3. Send AWD stock by October 14 if you replenish that way.
4. Keep sends to 8–10 weeks of cover. Peak storage rates punish overstock, and your IPI score affects the capacity you get next. See our IPI score and storage limits guide.

For the non-Amazon side, reset channel allocations to normal and rebuild safety stock ahead of November. Our safety stock guide for peak season walks through the formula.

Carrier surcharges landing in the same window

If you ship FBM or DTC orders yourself, your carrier costs rise in the same fortnight:

The figures in this table come from the USPS release on 2026 holiday shipping prices, Retail Dive's report on the 6% USPS peak increase, Supply Chain Dive on UPS 2026 holiday surcharges and Supply Chain Dive on FedEx 2026 peak fees. USPS gives a 3-pound, Zone 1 Ground Advantage commercial parcel as a $0.40 increase. That is small per box, but it applies to every USPS-shipped FBM and DTC order from October 4.

What to do this week: the checklist

Before the event (Oct 1–5)

• List every SKU with an approved deal and its FBA on-hand units.
• Project days of supply after the event at expected deal velocity; flag anything that falls under 28.
• Book restock shipments to Amazon for flagged SKUs now.
• Set per-channel reserves and buffers on every shared-stock SKU (peak hourly velocity × sync delay).
• Measure your top 20 SKUs and check their size tiers before peak fees make a wrong tier cost more.
• Update FBM shipping cost assumptions for the USPS change on October 4.
• Build ad budgets around the three daily drops and set stock-based pause rules.

During the event (Oct 6–7)

• Check stock and spend after each drop: midnight, 8 a.m. and 1 p.m. PT.
• Pull deal SKUs from other channels the moment a buffer is breached.
• Pause ads on SKUs projected under 28 days of supply unless the margin covers the fee.

After the event (Oct 8–14)

• Recalculate days of supply from event sales and ship restock for BFCM.
• Restore normal channel allocations and taper ads over two to three days.
• Log returns as they arrive, and keep them off other channels until someone inspects them.
• Book a day in late October to check FBA stock against orders and file reimbursement claims.
• Check Seller Central for your November capacity limit in the third full week of October.

On Oct 15

• Re-run margins with peak fees plus the 3.5% surcharge for FBA and MCF.
• Ship thin-margin MCF orders from your own stock or a 3PL where that is cheaper.

If one pool of stock feeds Amazon and your other stores during the event, you can connect them before Tuesday. Nventory's Free plan covers one channel with unlimited orders and no card, and the paid plans add more channels.