If you've just launched a Shopify, WooCommerce, or BigCommerce store, the question how does ecommerce merchant processing work for small online stores sounds like it should have a one-sentence answer. It doesn't — and that's exactly why most new merchants overpay.
Behind every successful checkout, four parties move money in coordination: the gateway, the processor, the acquiring bank, and the card networks. Once you understand who does what, picking the right setup (and saving 0.30–0.60% on every sale) gets a lot easier.
The five players in every ecommerce transaction
Before we get to fees, here's the cast. Every card payment your store accepts touches all five of these:
- Customer's card-issuing bank — Chase, Capital One, etc. They actually own the money.
- Card network — Visa, Mastercard, Amex, Discover. They route the authorization request.
- Acquiring bank (a.k.a. merchant bank) — the bank that holds your merchant account and deposits funds.
- Payment processor — moves the transaction data between gateway, networks, and banks.
- Payment gateway — the software layer your checkout actually talks to (Stripe, Authorize.Net, Braintree, Shopify Payments).
Step-by-step: what happens when a customer clicks 'Pay'
Here's the full lifecycle of a $100 order, in roughly 2 seconds of real time:
- 1. Authorization request — The gateway encrypts the card data and sends it to your processor.
- 2. Network routing — The processor passes the request to Visa/Mastercard, who hands it to the issuing bank.
- 3. Approval or decline — The issuer checks fraud signals, available credit, and AVS/CVV, then responds.
- 4. Hold placed — On approval, $100 is held (not yet captured) on the customer's card.
- 5. Capture — Usually triggered when the order ships. This converts the hold into a charge.
- 6. Settlement — Overnight, the processor batches all captures and pulls the money from issuers.
- 7. Funding — 1–2 business days later, your acquiring bank deposits the net amount in your operating account.
How fees actually stack up on a $100 sale
Most small stores look at one number — "2.9% + 30¢" — and stop there. But that headline rate hides three separate components, and all three are negotiable as you grow.
Interchange (the biggest piece)
Interchange is set by Visa and Mastercard and paid to the issuing bank. For a typical ecommerce Visa transaction, interchange runs about 1.80% + $0.10. For rewards cards or international cards, it can hit 2.30%+. Interchange is the same regardless of which processor you use — it's a pass-through cost.
Assessments (the network's cut)
Assessments are paid to Visa/Mastercard themselves, around 0.13–0.14%. Also a pass-through, also identical across all processors.
Processor markup (the only piece you control)
Everything above interchange + assessments is your processor's margin. Stripe, Shopify Payments, and PayPal use a flat blended model that bundles markup into a single rate. Interchange-plus pricing breaks it out so you can see exactly what you're paying — usually 0.20–0.40% + $0.10 above true cost for an established small store.
Flat-rate vs. interchange-plus: which one fits a small store?
If you're under roughly $25,000 a month in card volume, flat-rate pricing (Stripe, Shopify Payments) is almost always the right call. The simplicity beats the small savings you'd see from interchange-plus.
Once you cross $25k–$50k/month, interchange-plus through a dedicated merchant account routinely saves 0.30–0.60% on the effective rate. On $50k/month that's $1,800–$3,600 a year — straight to profit.
What small stores should optimize first
If you're starting from zero, focus on these four things in order. They have the biggest impact on how ecommerce merchant processing works for your specific store:
- Get full AVS and CVV checks enabled — improves interchange qualification and blocks obvious fraud.
- Turn on 3D Secure 2 for high-AOV orders — shifts chargeback liability to the issuer.
- Use the gateway's account updater — automatically refreshes expired card-on-file data, recovering 1–3% of subscription churn.
- Review your statement quarterly — once you have 6 months of data, benchmark your effective rate.
The short version: a gateway tokenizes the card, a processor moves it through the networks to the customer's bank, the bank approves, and your acquiring bank deposits the net 1–2 days later. The fees are interchange + assessments + processor markup — and the only piece you can negotiate is that last one.
For most small stores under $25k/month, Stripe or Shopify Payments is fine. Above that, it's worth comparing interchange-plus options. We help compare side-by-side based on your platform, AOV, and volume.
Frequently asked questions
What's a normal effective processing rate for a small ecommerce store?+
For typical ecommerce under $25k/month, 2.7–2.9% effective is normal on flat-rate pricing. On interchange-plus, the same store usually lands at 2.4–2.6% effective.
Do I need a merchant account for a small Shopify store?+
No. Shopify Payments, Stripe, and PayPal are all aggregated processors — they pool you under their merchant account. You only need a dedicated merchant account when you outgrow flat-rate pricing or sell high-risk products.
How fast do small stores get their money?+
Most aggregated processors pay out in 2 business days. Some (Stripe Express, Shopify Payments on certain plans) offer next-day. Dedicated merchant accounts typically settle next-day standard.
Why does my checkout sometimes decline real customers?+
False declines usually come from AVS mismatches, velocity rules, or out-of-the-box fraud filters set too tightly. Tuning these in your gateway typically recovers 1–3% of lost revenue.
Talk to an ecommerce payments specialist
Get a free side-by-side comparison tailored to your platform, AOV, volume, and risk profile.
No obligation. Fast review for online stores.