Most of us here have wired up Stripe or a gateway SDK at some point and moved on, because the integration is the easy part and the pricing page looks like one number. It is not one number, and knowing how it decomposes is the difference between a sensible processor decision and just paying whatever the default is.
Approval Is Not Settlement
When a card number hits your endpoint, the gateway encrypts it and passes it to the processor, which routes to the card network, which asks the issuing bank. The bank checks validity, funds and fraud rules and sends an approval back down the same chain. All of that happens in roughly two seconds.
What comes back is an authorization, not money. Settlement happens later, usually in end of day batches, which is why your deposits never line up with your sales day for day. If you are reconciling against a ledger, that gap is the source of most of the mismatches you will chase.
The Bill Has Three Parts and Only One Is Yours
Interchange goes to the bank that issued your customer's card. Visa and Mastercard set it, and no processor can discount it. For US online transactions it runs from about 1.65 percent plus 10 cents on a basic debit card to about 2.40 percent plus 10 cents on a rewards card, with the effective ecommerce average around 1.8 to 2.1 percent.
Assessments go to the card network itself, roughly 0.13 to 0.14 percent. Also fixed.
Processor markup is the only negotiable component. It is how your processor makes money, and on a flat rate plan it is bundled invisibly into the single advertised rate.
On a $100 order paid with a rewards card, the real breakdown is about $2.10 interchange, $0.14 assessment, and $0.25 to $0.50 markup. That is $2.49 to $2.74 total. The same transaction on Stripe's 2.9 percent plus 30 cents costs $3.20.
Where the Crossover Sits
Payment facilitators like Stripe, PayPal and Square aggregate you under their own master merchant account, which is why onboarding takes minutes with no underwriting. The tradeoff is that you share their risk profile, and their automated systems can freeze or hold funds without much recourse.
A traditional merchant account prices interchange-plus, meaning actual interchange plus a fixed markup, and it comes with underwriting, three to seven days of setup, monthly minimums and statement fees. Above roughly $20,000 a month in volume, interchange-plus almost always comes out cheaper even after those fixed costs. Below that, the flat rate is genuinely a fair price for the simplicity.
The number worth computing is your own effective rate: total fees divided by total volume for last month. Most people have never run it. The full breakdown of gateways, fees, settlement and PCI scope covers the rest of the chain if you want the long version.
The Practical Takeaway
Do not go looking for a processor who will lower your interchange, because that is not a thing anyone can sell you. Compare markup, compare the fixed monthly costs against your volume, and instrument your own reconciliation so you can see the auth to settlement gap rather than guessing at it.
