Enter a sale once, see what you'd actually keep on eBay versus Amazon side by side.
eBay nets you
$0.00
more on this sale
eBay
BETTER DEAL
Sale price$0.00
Platform fee-$0.00
Shipping-$0.00
Cost of goods-$0.00
Ad spend-$0.00
Net profit$0.00
Margin: 0%
Amazon
BETTER DEAL
Sale price$0.00
Platform fee-$0.00
Shipping-$0.00
Cost of goods-$0.00
Ad spend-$0.00
Net profit$0.00
Margin: 0%
Why the same sale pays differently on each platform
The same item at the same price doesn't net you the same profit on eBay and Amazon. Fee structures differ, and depending on your category and account type, one platform quietly keeps more of your sale than the other. Most sellers guess based on gut feel instead of actually running the numbers per listing.
The habit worth building as a reseller is checking this before you list something, not after. A product with a thin margin at full price can turn into a loss the moment you run a sale or an ad campaign on it, on either platform.