Prime Big Deal Days submissions close September 8 for an event Amazon has not dated. Across eight categories the October spike ran 1.82x — and five of eight gave it back the next week

Tomorrow is the last day to submit a Prime Big Deal Days deal. Amazon has not said when Prime Big Deal Days is.

That is not a complaint about communication. It is the actual shape of the decision on an operator’s desk this week: commit a discount, a promotion fee and an inbound shipment against an event whose dates are still unpublished, or sit it out and keep the margin. The question worth answering before tomorrow is not whether the event is big. It is whether the lift is yours — incremental volume you would not otherwise have sold — or volume you were going to get anyway, moved forward a week and discounted on the way.

So we measured it.

The dates you actually have

Amazon opened holiday deal submissions on July 8, 2026 and published the windows and arrival deadlines at the same time.

Milestone	Prime Big Deal Days	Black Friday / Cyber Monday
Deal submission window	July 8 – September 8, 2026	July 8 – October 20, 2026
$50 early-submission discount	August 5 (closed)	September 5 (closed)
AWD arrival	September 2	October 14
FBA, minimal shipment splits	September 9	October 21
FBA, Amazon-optimized splits	September 16	October 28

The September 16 line is the one that binds most sellers, because Amazon-optimized shipment splits is the default most accounts run. Both early-submission discounts have already passed, so a deal submitted tomorrow carries the full upfront promotion fee — reported at $100 per promotion plus 1.5% of promotional sales, capped at $5,000.

And the event dates themselves remain unannounced. Last year’s edition ran in early October; that is a precedent, not a schedule. Anyone telling you the 2026 dates today is inferring them.

That unpublished date carries a real cost consequence. Amazon’s holiday peak fulfilment period runs October 15, 2026 to January 14, 2027, at an average increase of $0.32 per unit with the 3.5% fuel and logistics surcharge applying on top, and it is triggered by the date a unit ships out rather than the date it was ordered. If the event lands in early October as it did last year, the units you sell into it ship before that line. Black Friday units do not. That is a genuine cost advantage for the October window — and it is entirely contingent on a date Amazon has not given you. We worked through how much Q4 demand sits on the surcharged side of that line separately.

What last year’s October spike was actually worth

We pulled weekly search-volume history from Helium 10 for eight US head terms chosen to span deal-heavy categories, replenishment categories, a weather-driven control and a seasonal control: air fryer, robot vacuum, electric toothbrush, dog bed, protein powder, laptop stand, space heater and christmas decorations. The window runs August 2 to December 13, 2025.

The measurement choice matters more than the pull. Comparing the event week against a September baseline sounds natural and is badly wrong for any category with a seasonal trend — it credits the event with demand the calendar was always going to deliver. So the headline metric here is a local ratio: the event week against the mean of the two weeks either side of it. That removes the trend and isolates the spike.

Keyword	Event week (Oct 11)	Shoulder avg	Local lift	vs Sep baseline
robot vacuum	476,435	167,317	2.85x	2.63x
air fryer	1,571,612	731,787	2.15x	2.01x
christmas decorations	1,029,116	480,920	2.14x	3.30x
electric toothbrush	620,029	361,514	1.72x	1.62x
protein powder	1,004,471	606,208	1.66x	1.44x
dog bed	518,403	359,497	1.44x	1.40x
space heater	252,751	190,227	1.33x	3.17x
laptop stand	252,961	196,902	1.28x	1.13x

The basket mean is 1.82x, the range 1.28x to 2.85x, and only three of eight terms cleared 2.0x.

Look at the two right-hand columns for space heater. Against a September baseline it reads as a 3.17x event — the single most impressive number in the table. Against its own shoulder weeks it is 1.33x, the second weakest in the basket. The difference is October weather, which was going to arrive whether or not Amazon ran a sale. Every category with a seasonal ramp carries a version of this gap, and it is the most common way a deal gets justified after the fact.

The number that decides it: the week after

A spike is only worth a discount if the demand was incremental. The cleanest test available is the week following the event compared against the week preceding it.

Keyword	Week before (Oct 4)	Week after (Oct 18)	After ÷ before
robot vacuum	193,504	141,130	0.73x
laptop stand	210,435	183,369	0.87x
air fryer	772,557	691,017	0.89x
electric toothbrush	379,320	343,707	0.91x
protein powder	627,857	584,559	0.93x
dog bed	349,376	369,618	1.06x
christmas decorations	349,508	612,331	1.75x
space heater	90,849	289,605	3.19x

Five of the eight came back below where they started. Robot vacuum — the category with the largest spike in the basket at 2.85x — had the deepest hangover, falling to 0.73x of its pre-event week. The three that did not fall are the three on independent ramps: space heater and christmas decorations were climbing through October on weather and calendar, and dog bed was roughly flat at 1.06x.

That pattern is the point. In this basket, the categories that spiked hardest also gave the most back. The event moved demand forward about a week for most of them, and the seller paid a discount plus a promotion fee for the privilege of selling units that were coming anyway. This is the same pull-forward dynamic we found when we audited Prime Day demand, and it shows up here in a smaller, sharper form.

October versus Black Friday

One more comparison worth having before tomorrow, since Black Friday submissions stay open until October 20 and the same inventory can only be committed once.

Measured locally — each peak against its own shoulder weeks — the October event beat late November for seven of the eight terms: 1.82x average in October against 1.40x for the Black Friday and Cyber Monday peak. The late-November peak still carries far more absolute volume; air fryer ran 1,688,092 at the end of November against 1,571,612 in October, and robot vacuum 631,581 against 476,435. But that is because November sits on a seasonal base that is already high, not because the event lifts harder. Black Friday is a peak on a plateau. The October event is a spike in a flat field.

If your constraint is units, November is the bigger pool. If your constraint is margin, the October spike is the sharper instrument — and the shorter one.

A note on the data

Helium 10 documents these weekly points as trailing 30-day search volume. The observed behaviour in this pull is a single-week spike that decays fully by the following week, which is how a discrete weekly series behaves rather than a 30-day rolling one. We report the points exactly as returned and compare like with like throughout — every ratio in this note is built from points on the same series, so the comparison holds regardless of which window the vendor applies. Search volume is also a demand proxy, not units sold; it tells you where attention moved, not what converted.

The Operator Read

Tomorrow’s decision is smaller than the calendar makes it feel, and it is answerable with data you can pull in twenty minutes.

• Run the local-ratio test on your own head terms. Event week against the mean of the two weeks either side. If you use a September baseline instead, you will overstate the lift on every seasonal SKU you own.
• Then run the week-after test. If the following week lands below the preceding one, you are looking at a pull-forward. Five of our eight categories were. Price the deal as a margin transfer and decide whether the rank and review velocity are worth it, because the units are not incremental.
• Do not submit a deal to hold rank you can hold with ads. If the goal is visibility through the event rather than volume, the cost comparison is against your ad spend for that week, not against your full-price margin. If you have not audited what that week actually costs you in ads, that is the cheaper thing to fix first — our Amazon PPC audit starts there.
• Treat September 16 as the fixed point. The event date is unknown; the inbound deadline is not. Build the schedule against the deadline you have.
• Keep the Black Friday option open. That window runs to October 20, the absolute volume is larger, and you will know considerably more about the season by then than you do tonight.

The honest summary: for most categories in this basket, the October event is a real and sharp spike that mostly borrows from the following week. That is worth paying for when you need rank, velocity or a review base going into November. It is not worth paying for if you thought you were buying incremental sales.