Amazon Sub Same Day Bidding: What a Two-Hour Badge Is Worth to Your Margin

For most brands, paying for Amazon's Sub Same Day delivery this BFCM means paying for sales you would have made anyway. You pay the fee on every unit that ships in two hours, not just the extra sales that speed brings in. At Amazon's own 12% lift, you can afford a fee of about 11% of your margin per unit. That is before any holiday discount.

Sub Same Day is Amazon's fastest delivery tier. Orders ship from small warehouses close to shoppers and arrive in a few hours. The "sub" means under: delivery in less time than regular same-day, which can arrive as late as that night. Amazon describes these sites as mini fulfillment centers built for ultra-fast delivery.

Since August, Amazon has invited some FBA sellers to name a price per unit to get products into this network. Amazon calls it a reservation fee. Everyone else calls it a bid. It looks like a shipping decision, but it is really a margin decision, and it ties into your ad spend on the same product.

What Amazon launched, and how the reservation fee works

Amazon runs Sub Same Day sites near about 2,300 metro areas. They deliver in 2 to 5 hours. They stock about 100,000 products, a small slice of the millions in a regular fulfillment center. Amazon has always chosen which products go there, for free, based on demand, price, and stock levels. That free placement continues.

What's new is the FBA Sub-Same Day Placement Reservation program, explained in Seller Central help pages. It lets invited sellers ask for a spot for ASINs Amazon did not pick on its own.

Two details matter for the math. First, a higher fee does not guarantee a spot, and getting a spot does not guarantee sales. Second, Amazon says products in the network have seen 12% higher sales than standard FBA. One Amazon page says "on average." Another says "up to." Both say results vary, and Amazon does not explain how it got the number.

Shoppers see this as a delivery time, not a new badge. Since March, eligible items show "1-hour" or "3-hour" text, with matching search filters and a storefront at amazon.com/getitfast. Prime members pay $9.99 for 1-hour and $4.99 for 3-hour delivery. Only shoppers near a Sub Same Day site see the option. Next to a Prime listing that already says tomorrow, the shopper is choosing between a few hours and tomorrow.

You pay on every unit, not just the extra ones

The fee applies to every unit that ships through Sub Same Day, including the ones you would have sold at normal Prime speed. Only the lift is new money. So the most you can pay per unit is the share of units that are truly extra, times what each extra unit earns.

Say 1,000 units a month would sell anyway, and the program lifts that by 12% to 1,120. The 120 extra units earn $9.00 each, so you make $1,080 more. Spread that over all 1,120 units you pay on, and the break-even fee is about $0.96. Some guides online divide the $1,080 by only the 120 extra units. That makes it look like you could pay up to $9.00 a unit. It charges the fee on the wrong units.

The example below uses one product: a $25 item with $7 product cost, a 15% referral fee, and a $5.25 FBA fee, so $9.00 of margin before ads. Its ACoS is 25%, and 40% of its sales come from ads. That works out to $2.50 of ad cost per unit on average, leaving $6.50 after ads.

Your ad plan decides which margin to use. If you keep your ad budget flat, the extra units cost nothing extra in ads, so use margin before ads. If you raise spend to keep ACoS steady, each extra unit carries some ad cost, so use margin after ads. Most teams land between the two columns.

One more reason to stay near the low end. The paid program only covers ASINs Amazon did not place for free, and Amazon picks free products based on demand. So the products you can bid on are the ones Amazon passed on. Expect less than the 12% Amazon saw on the products it chose.

What faster delivery changes: our FBA vs FBM data

Faster delivery wins the sale, not the click, and the biggest gain comes from getting to Prime at all. We looked at one home and garden brand on Trellis that sells the same ASINs as both FBA and FBM, over the 90 days to Oct 27, 2026.

Shoppers clicked the slower offer just as often. But once on the page, they bought the Prime offer about 1.8x as often. FBA converted better in 100 of the 157 pairs where both sides got clicks.

The brand also moved 59 ASINs from FBM in 2025 to FBA in 2026. We compared them with 141 ASINs that stayed FBM both years, over the same months. For the ASINs that moved, unit session percentage rose from 7.4% to 9.4%. For the ones that stayed, it fell from 7.6% to 7.1%. Median sales per ASIN rose 35% for the movers, and their ACoS fell from 85% to 67%. Sales for the rest stayed flat.

That is what a big speed jump looks like: from several days to one or two, plus the Prime badge. Sub Same Day is a much smaller jump, from tomorrow to today. If the big jump is worth about a quarter more conversion, a 12% lift for the small one is a best case, not a number to plan on. For planned buys like doormats and decor, where nobody needs it in two hours, expect close to none.

A word of caution on our numbers. This is one brand in one category, and moving from FBM to FBA is a different change from moving from tomorrow to today. Use it to set expectations, then check it against your own ASINs. Your own lift is the only number worth bidding on.

The same account showed one more trap. Ads often kept pointing at the slower offer. The FBM versions got $70.8K of spend, against $43.2K for the FBA versions of the same ASINs. If you pay for speed while your ads send shoppers to the slow offer, you pay twice.

BFCM makes the math worse, not better

Traffic jumps on Black Friday and Cyber Monday, so it sounds like the time to pay for speed. It is the opposite. The share of extra units depends on the lift, not on volume, so more traffic does not raise the ceiling. Instead, the peak shrinks both the lift and the margin at once.

• Deal shoppers buy on price. During BFCM, the deal badge, the price, and reviews win the order. Most shoppers buy gifts weeks ahead, so two-hour delivery rarely decides which listing they pick. Lower lift means a lower ceiling.
• Discounts cut the margin. Take the same $25 item at 20% off. Price drops to $20, the referral fee to $3.00, and margin before ads falls from $9.00 to $4.75, or $2.75 after ads.
• Higher volume makes the bill bigger, not the payoff. You pay the fee on every unit, and most of the surge would have sold at Prime speed anyway.
• Space gets tight. Amazon has told sellers that space in the network gets tight in November and December. It also ranks requests partly on what makes money for Amazon. Peak season is when your fee buys the least.

Put it all together and the example product's ceiling drops from $0.96 (full price, 12% lift) to about $0.23 (20% off, 5% lift), or $0.13 if ads grow with sales. A fee set in October from full-price margin can lose money on every discounted unit in November.

The exception: the last few days before Christmas

There is one stretch where speed does sell: the last few days before Christmas, after regular shipping cutoffs pass. A shopper who forgot a gift on December 23 needs it before the 25th. That is when "arrives today" becomes the reason to buy.

That window also eases the BFCM problems. Many deals have ended by then, so you may sell closer to full margin. And fewer listings can still arrive in time, so speed can win the sale on its own. If you test Sub Same Day anywhere this year, test it here.

When it is worth testing, and how

Test Sub Same Day on a few ASINs where speed is the reason to buy and the margin can carry a fee. Do it only after you have the bigger speed gains in place.

1. Get to Prime first. If a lot of your volume still ships FBM, start there. In our data the same product converted about 1.8x better on FBA, a far bigger gain than Sub Same Day is likely to give.
2. Pick items people need fast, with healthy margin. Think consumables people run out of, baby and pet basics, chargers, and last-minute gifts. Skip planned purchases and thin-margin products.
3. Check what Amazon already placed for free. Download the eligible list in Capacity Manager. An ASIN already in the network for free needs no fee.
4. Set the fee from your margin at the price you will actually sell at. Use the deal price for any period with a deal. Assume a low lift, not Amazon's average.
5. Plan around the lock. Requests are decided monthly. Once granted, you cannot cancel within 30 days of the period. Check the December request deadline in Capacity Manager now, not after Black Friday.
6. Point ads at the fast offer. If an ASIN has more than one offer, make sure campaigns send shoppers to the one that ships two-hour.
7. Measure your own lift, then decide. Start with a handful of ASINs for one period. Compare each one's profit after the fee with the month before, and with similar ASINs you left out. Amazon's performance summary and fee report on the Sub Same Day tab give you the units and the charge. If your real lift beats your guess, add ASINs next period.

The Sub Same Day bid ceiling calculator

We built a free calculator that turns this math into one number per ASIN: the most you can pay per unit before faster delivery starts costing you money. Use it two ways: to check whether a BFCM fee makes sense (usually it does not), and to size a small test for the last-minute Christmas window.

Why it matters

Amazon asks for a dollar amount per ASIN, every month, with no price list to go by. The right answer depends on numbers only you have. It changes whenever price, fees, or ACoS change, which in Q4 is weekly. Guesses tend to run high. The online examples that charge the fee only on extra units overstate what you can afford by about nine times at a 12% lift. And a wrong fee does not fail loudly. Sales go up, the faster delivery time shows, and you lose margin on every unit you would have sold anyway.

How it helps

• Shows the break-even fee before you type a number into Capacity Manager, so your bid starts from margin, not a hunch.
• Gives a range across low, Amazon-average, and high lift, so you are not betting on one figure Amazon has not explained.
• Shows the ceiling two ways, with your ad budget held flat and with ACoS held flat, because that choice changes the answer.
• Lets you switch on a promo discount to see what the ceiling becomes during a deal.
• Gives a verdict in plain words: test, test small, or skip.

How it works

1. Enter the price, product cost, referral fee, and FBA fee for one ASIN.
2. Enter its ACoS and the share of its sales that come from ads.
3. Pick an expected lift. The default is 5%, with 12% shown as Amazon's average.
4. Optionally add a promo discount for BFCM or any deal period.
5. Read your ceiling, the share of fee you pay on sales you would have made anyway, and the verdict.

The calculator runs in your browser and stores nothing. It does not know your real lift, so bid under the ceiling it gives you, run a small test, then plug in the lift you actually measured.

The bottom line for eCommerce teams

Sub Same Day can lift sales for some products. But the fee lands on every unit, and most of those units would have sold anyway. During BFCM, the deal does the selling, the discount shrinks your margin, and the most sellers are competing for space.

• Get to Prime before paying for two-hour delivery. That is where our data shows the conversion jump.
• Set any fee from your margin at the price you will sell at, with a low lift.
• Save your test for high-margin items people need fast, in the days before Christmas, with ads pointed at the fast offer.

Sources

• AMZBase: What the SSD reservation fee actually costs (quotes Amazon's Placement Reservation help page)
• SellerHow: Sub Same-Day bidding, official pages checked Aug 31, 2026
• Shopifreaks: Amazon tells sellers to bid for faster sub-Same Day delivery, Aug 31, 2026
• PrimeXBT, republishing Business Insider: Amazon asks third-party sellers to bid for faster shipping access, Aug 29, 2026
• The Conveyor: Amazon lets FBA sellers bid for same-day delivery placement, Sep 2, 2026
• EcomCrew: Amazon just turned fast delivery into an auction, Sep 9, 2026
• About Amazon: 1-hour and 3-hour delivery, Mar 17, 2026
• Business Wire (Amazon): Amazon opens first Same-Day fulfillment center in Massachusetts, Mar 17, 2022
• Trellis account data: one US home and garden brand, FBA vs FBM SKUs on the same ASINs, 90 days to Oct 27, 2026, plus same-month 2025 vs 2026 comparison, anonymized