# Ecommerce Payment Processing: How It Works and What It Costs in 2026

> How ecommerce payment processing works, what it costs, and how to choose a processor in 2026, with real fee data from Stripe, PayPal, and Square.

Last updated: 2026-09-13T09:00:00

Canonical URL: https://crevio.co/blog/ecommerce-payment-processing

**Every online sale you make passes through five separate companies before the money is actually yours, and most of them take a cut before you see a cent.** Ecommerce payment processing is the plumbing behind that transfer: the gateway, processor, card network, and banks that turn a clicked "Pay" button into settled funds. Get it right and it's invisible. Get it wrong and you're either losing sales at checkout or losing margin to fees you never audited.

- **A card payment involves at least five parties**: the gateway, the processor, the card network, the issuing bank, and the acquiring bank, each one adding a fee.
- **"Processing fees" are really three fees stacked together**: interchange (set by the card networks), assessment (a network fee), and markup (your processor's own cut, the only negotiable part).
- **Most small businesses pay 1.5-3.5% per transaction**, and flat-rate processors like Stripe, Square, and PayPal publish one number that already bundles all three layers.
- **Payment security failures cost real sales**: 18% of US shoppers who abandon checkout say it's because they didn't trust the site with their payment details, according to the [Baymard Institute](https://baymard.com/lists/cart-abandonment-rate).

### Quick Comparison

| | Stripe | PayPal Checkout | Square (online) | Interchange-Plus |
|---|---|---|---|---|
| **Standard rate** | 2.9% + $0.30 | 3.49% + $0.49 | 2.9% + $0.30 | ~1.8-2.5% + a small fee |
| **Pricing model** | Flat-rate | Flat-rate | Flat-rate | Cost-plus, varies by volume |
| **Best for** | Developers, custom checkout flows | Buyers who already trust PayPal | Businesses already on Square POS | High-volume sellers who can negotiate |
| **Setup complexity** | Low to moderate (APIs, some code) | Very low (hosted button) | Low | Higher, usually needs a sales conversation |

![A five-step diagram showing how a card payment moves from checkout through the payment gateway, processor, card network, and issuing bank to final settlement](https://crevio.co/vite/assets/payment-processing-flow-BcNPWhy8.svg)

## How Ecommerce Payment Processing Actually Works

When a shopper enters their card details and clicks "Pay," what looks instant is actually a real-time conversation between five separate parties, and it usually resolves in under three seconds.

### The Five Parties in Every Transaction

1. **The payment gateway** captures and encrypts the card data at checkout, then forwards an authorization request. Think of it as the digital equivalent of a card reader.
2. **The payment processor** takes that request and routes it onto the card network's rails, acting as the middleman between your business and the banking system.
3. **The card network** (Visa, Mastercard, American Express, Discover) relays the request to the correct issuing bank and sets the interchange rate for that card type.
4. **The issuing bank** is the shopper's own bank. It checks their available balance or credit limit, runs fraud checks, and approves or declines in real time.
5. **The acquiring bank** is your business's bank. Once approved, it's the one that actually receives and settles the funds into your merchant account, usually one to two business days later.

Approval or decline then travels back through the exact same chain, which is why a shopper sees a result in seconds even though five different companies just talked to each other.

### Payment Gateway vs. Payment Processor: What's the Difference

These two terms get used interchangeably, and it causes real confusion when comparing providers. The **gateway** is the technology layer: it captures and encrypts card data and passes it along. The **processor** is the company that actually moves the transaction through the card networks and handles settlement. Historically these were separate vendors you had to stitch together yourself. Today, providers like Stripe, Square, and PayPal bundle both roles into a single account, which is a large part of why flat-rate ecommerce payment processing became the default for small and mid-size businesses instead of the multi-vendor setups larger enterprises still sometimes run.

## What Ecommerce Payment Processing Really Costs

A "2.9% processing fee" isn't one fee at all. It's three separate charges bundled into a single published number, and only one of the three is something your processor actually controls.

![A stacked bar showing a 2.9% processing fee split into interchange, assessment, and processor markup, with cards explaining who receives each layer](https://crevio.co/vite/assets/processing-fee-stack-DZ7VaMND.svg)

- **Interchange** (roughly 1.5-2.5% depending on card type) goes to the shopper's issuing bank. It's set by the card networks, not your processor, and varies by whether the card is debit, standard credit, or a premium rewards card.
- **Assessment** (a small fraction of a percent) goes to Visa, Mastercard, or the relevant network simply for using their rails.
- **Markup** is what your processor charges for everything it actually built: the gateway, fraud tools, payouts, reporting, and support. This is the only layer that changes when you switch providers.

That breakdown matters because it explains why "just negotiate a lower rate" only works up to a point. A processor can shave its own markup, but it can't touch interchange or assessment, which is why even the cheapest interchange-plus deal in the world still has a floor.

### Flat-Rate vs. Interchange-Plus Pricing

Most small and mid-size ecommerce businesses use **flat-rate pricing**: one published percentage plus a fixed fee, regardless of card type. It's predictable and easy to compare, which is exactly why Stripe, Square, and PayPal all default to it.

![A bar chart comparing published online processing rates: Stripe and Square at 2.9% plus 30 cents, PayPal Checkout at 3.49% plus 49 cents, and interchange-plus around 1.8 to 2.5% plus a per-transaction fee](https://crevio.co/vite/assets/processor-fee-comparison-DWwAq73D.svg)

**Interchange-plus pricing** separates the layers: you pay the real interchange and assessment cost, plus a smaller, explicit markup on top. It's harder to compare at a glance because your effective rate shifts with your card mix, but at meaningful volume it usually lands lower than flat-rate. The tradeoff is access: interchange-plus deals typically require talking to a sales team and processing enough volume to be worth negotiating, which is why most businesses under a few hundred thousand dollars a year in card sales stick with a flat-rate provider instead.

One number worth keeping in mind either way: [Bankrate](https://www.bankrate.com/credit-cards/business/merchants-guide-to-credit-card-processing-fees/) puts the average effective card processing cost for small businesses at 1.5% to 3.5% per transaction, and [NerdWallet](https://www.nerdwallet.com/article/small-business/credit-card-processing-fees) notes most small businesses land toward the higher end of that range specifically because flat-rate pricing is simpler to set up than negotiating interchange-plus terms.

## Ecommerce Payment Processors Compared

There's no shortage of processors to choose from, and [Whop's rundown of the space](https://whop.com/blog/ecommerce-payment-processing/) goes deep on more than a dozen of them if you want the exhaustive list. Here's the shorter version: the handful that actually matter for most ecommerce businesses, and where each one genuinely wins.

- **Stripe** is the default choice for anything that needs a custom checkout experience or deeper API access. Its documentation and developer tooling are the best in the category, which is exactly why it's the processor most website builders and platforms, Crevio included, build on top of rather than compete with.
- **PayPal** wins on buyer trust. A large share of online shoppers already have a PayPal account, and offering it as a checkout option can lift conversion simply because it removes the "type in my card number on a site I don't fully know" moment. Its higher published rate (3.49% + $0.49 for Checkout) is the tradeoff for that trust.
- **Square** is the strongest fit if you already run a physical location on Square's point-of-sale hardware and want your online and in-person sales unified in one dashboard.
- **Adyen and Checkout.com** serve larger, often global merchants who need multi-currency settlement and the kind of volume-based pricing only enterprise sales teams offer. Most small and mid-size sellers won't need to go this route.
- **Whop** positions itself as merchant-of-record infrastructure for internet businesses specifically, with orchestration across multiple payment providers and international coverage as its main pitch. That's a genuinely different problem than the one most single-storefront sellers have, and it's worth a look if you're managing tax compliance across many countries at once.

None of these is universally "best." A developer-heavy team building a custom checkout, a solo seller who wants PayPal's trust signal, and a business already running Square hardware in a physical store all have different right answers, and picking based on brand recognition alone is how businesses end up paying for capabilities they don't use.

## PCI DSS Compliance and Security: What You're Actually Responsible For

If you accept card payments online, PCI DSS (Payment Card Industry Data Security Standard) compliance isn't optional. It's a set of requirements from the major card networks covering how card data is stored, transmitted, and protected, and every business that touches card data falls somewhere on its compliance scale.

The good news for most ecommerce businesses: using a hosted checkout, embedded payment element, or redirect flow from a provider like Stripe, PayPal, or Square means your servers never actually touch raw card numbers, which puts you in the lowest, simplest compliance tier (often a short self-assessment questionnaire rather than a full audit). The moment you build your own form that collects and transmits card numbers directly, your PCI scope, and your liability if something goes wrong, grows substantially. For the overwhelming majority of ecommerce businesses, letting the processor's hosted or embedded checkout handle card capture isn't just easier, it's the materially lower-risk choice.

Security has a direct revenue impact too, not just a compliance one. Baymard's abandonment research found that 18% of US online shoppers have abandoned a purchase because they didn't trust the site with their payment information, right behind concerns about surprise costs and account-creation friction. A checkout that visibly uses a recognized processor, shows familiar card logos, and doesn't ask for more information than necessary isn't just a compliance decision. It's a conversion one, and our guide to [ecommerce conversion rate benchmarks](/blog/ecommerce-conversion-rate) covers what a healthy checkout completion rate actually looks like.

## How to Choose an Ecommerce Payment Processor

Work through these in order, since the wrong choice compounds every month you stay on it:

1. **Total cost at your real volume, not the headline rate.** Model your actual monthly card volume against both a flat-rate quote and an interchange-plus quote. The "cheaper" one on paper isn't always cheaper at your specific transaction size and average order value.
2. **Where your customers actually are.** Selling internationally? Cross-border and currency conversion fees (commonly an extra 1-1.5% on top of the base rate) can matter more than the base rate itself.
3. **Checkout experience, not just backend cost.** A hosted redirect is the simplest to set up; an embedded or fully custom checkout keeps shoppers on your domain and tends to convert better, at the cost of more integration work.
4. **Subscription and recurring billing support**, if you sell memberships or subscriptions rather than one-time purchases. Not every processor handles failed-payment retries, dunning, and proration the same way, and this is worth checking before you build around one. If you're still deciding between a one-time and recurring model in the first place, our guide on [membership vs. one-time sales](/blog/membership-vs-one-time-sales) walks through that decision before the processor question even comes up.
5. **Payout speed and dispute handling.** How fast funds actually land in your bank account, and how much manual work a chargeback creates for you, varies more between processors than most comparison charts show.
6. **Developer resources, if you're integrating yourself.** If you or your team will be writing against the API directly, documentation quality and SDK maturity are worth weighing as heavily as the rate itself.

## Common Ecommerce Payment Processing Mistakes That Cost Sales

- **Building a custom card form instead of using a hosted or embedded checkout.** It looks more "custom," but it pulls you into a heavier PCI compliance tier for a benefit shoppers rarely notice.
- **Hiding shipping and taxes until the final step.** Baymard's research lists "extra costs too high" as the single biggest cause of checkout abandonment at 48%, ahead of every payment-specific concern combined.
- **Ignoring international card fees until a customer flags a surprise charge.** Cross-border and currency-conversion fees are easy to miss when you're only testing checkout with a domestic card.
- **Treating chargebacks as a rare edge case instead of a real cost line.** [Mastercard's 2026 research with Datos Insights](https://www.mastercard.com/us/en/news-and-trends/Insights/2025/what-s-the-true-cost-of-a-chargeback-in-2025.html) puts the fully loaded average cost of a single chargeback at $128 once processor fees and internal handling time are counted, well above the disputed transaction amount itself in most small-ticket ecommerce sales.
- **Never revisiting your rate after your volume grows.** A flat-rate deal that made sense at $5,000 a month in sales can be leaving real money on the table once you're doing $50,000, and interchange-plus only becomes worth the negotiation at higher volume.

## How Crevio Handles Payment Processing For You

![A comparison of building payment processing yourself versus selling through Crevio, where checkout, PCI compliance, and payouts are already wired in](https://crevio.co/vite/assets/crevio-payment-setup-DRvRBQsN.svg)

Worth being direct about where [Crevio](https://crevio.co/) fits into everything above, since this article is about exactly the decision Crevio removes for its own sellers. Crevio is an AI business builder: you describe what you want to sell and it builds the storefront, product, and checkout for you. Payment processing runs on Stripe underneath, using Stripe's custom UI mode so the checkout stays embedded in your own storefront rather than redirecting to a separate page, and it supports both one-time purchases and subscriptions out of the box.

That means most of the choices in this article, gateway versus processor, flat-rate versus interchange-plus, how much PCI scope you're taking on, aren't decisions you have to make yourself when you sell through Crevio. What you do pay is Stripe's own processing cost plus Crevio's platform fee, which scales with your plan: 5% on the free Starter plan, 2.5% on Pro ($20/month), and 1% on Business ($50/month). There's no plan with a 0% fee, and it's worth saying plainly that this platform fee sits on top of standard card processing costs, not instead of them, the same way any platform fee works on any hosted storefront.

If you're building a subscription product on top of Crevio, price variants support their own trial periods independent of how Crevio itself is priced, so you're not boxed into one billing structure just because the platform is. For a broader look at getting a business off the ground before payments even enter the picture, our guide on [how to start an online business in 2026](/blog/how-to-start-an-online-business) covers the steps that come first, and our [pricing guide for digital products](/blog/how-to-price-your-digital-products) is the natural next read once your checkout is actually live.

Pick a payment processor the way you'd pick a landlord, not a vendor: you're going to live with their fees, their support, and their fine print on every single sale you make from here on out, so the few hours spent understanding the stack now are cheaper than discovering a bad fit a thousand transactions in.

## FAQ

### What's the difference between a payment gateway and a payment processor?

A payment gateway is the technology that captures and encrypts card data at checkout and sends it onward for authorization. A payment processor is the company that actually routes that request through the card networks and handles settlement into your account. Modern providers like Stripe, Square, and PayPal bundle both into a single account, which is why the terms get used interchangeably in practice even though they describe different jobs.

### How much does ecommerce payment processing cost?

Most flat-rate processors charge 2.9% to 3.5% plus a fixed fee (commonly $0.30 to $0.49) per successful online card transaction. [Bankrate](https://www.bankrate.com/credit-cards/business/merchants-guide-to-credit-card-processing-fees/) puts the typical effective range for small businesses at 1.5% to 3.5% overall, with the exact number depending on card type, whether you're on flat-rate or interchange-plus pricing, and international or currency-conversion surcharges.

### Do I need to be PCI compliant to sell online?

Yes, in some form, if you accept card payments at all. The scope of what's required depends on how you handle card data: using a hosted or embedded checkout from a processor like Stripe or PayPal keeps you in the simplest compliance tier, usually a short self-assessment questionnaire. Building your own form that directly captures card numbers pushes you into a more demanding compliance tier with real security and liability implications.

## Related Blog Posts

- [How to Start an Online Business in 2026: The Complete Guide](/blog/how-to-start-an-online-business)
- [How to Price Your Digital Products: A Step-by-Step Guide](/blog/how-to-price-your-digital-products)
- [How To Sell Digital Products in 2026: The Complete Guide](/blog/how-to-sell-digital-products)
- [Free Trial vs. Freemium: Which Pricing Model Wins in 2026?](/blog/free-trial-vs-freemium)
- [Membership vs. One-Time Sales: Which Model Fits Your Content?](/blog/membership-vs-one-time-sales)