Quick answer:
A payment processor is the company that moves card transaction data between your acquiring bank and the customer’s card network and issuing bank to get a payment authorized and then settled.
Processors charge a percentage of each sale plus a flat per-transaction amount, and they price card-present and card-not-present sales differently. Most small retailers come across a processor bundled inside a bigger product like Square, Shopify Payments or SumUp rather than signing up for one on its own.
Processing is the single largest recurring cost attached to card acceptance, charged on every sale your store makes. A fraction of a percentage point sounds trivial until you multiply it across a full year of revenue.
The word also confuses more retailers than any other payments term, because four different jobs use each other’s names. Here is your guide to what a processor actually does, what it costs in 2026, and how to tell it apart from everything it gets mistaken for.
What is a Payment Processor? The Basics
A payment processor has one job: get a card transaction authorized and then coordinate the movement of funds between the banks involved.
It is a data business, not a banking one. The processor packages the transaction, sends it onto the card network rails, receives the approval or decline, and hands the answer back to the terminal or your checkout page.
What it does not do is hold your money. Settled funds land in a merchant account held at an acquiring bank, and that bank is the party carrying the risk of disputes and refunds.
Processors do tend to bundle extra services around the core job. Stripe’s own explainer describes processors offering fraud detection and dispute management alongside authorization, which is why the role has spread so far beyond simple message routing.
Using a processor normally requires a merchant account, whether you contract one separately or inherit one from a bundled provider. Checkout software on its own does not.
Processor vs Gateway vs Merchant Account vs Acquirer
This is the question behind most searches for the term, so here are the four roles side by side.
| Role | What it does | Holds funds? | Carries dispute risk? |
|---|---|---|---|
| Payment gateway | Captures and encrypts card data at checkout or the terminal and passes it on | No | No |
| Payment processor | Gets the transaction authorized and coordinates settlement between banks | No | No |
| Merchant account | The bank account settled card funds land in before payout | Yes | It is the account the money is clawed back from |
| Acquirer | The bank that underwrites and holds the merchant account | Yes | Yes |
The gateway’s full mechanics, including hosted pages, tokenization and 3D Secure, are covered in the entry on what a payment gateway is and how it works. The underwriting, reserve and high-risk side belongs to the merchant account entry.
Two more distinctions are worth nailing down. A card network is not a processor. Visa, Mastercard and American Express operate the rails that route the authorization request and set the interchange fees. The processor is the company that packages a transaction and puts it onto those rails.
And an acquirer is not a processor either. Per Stripe’s comparison of the two, the acquirer underwrites the merchant, holds the account and absorbs the chargeback exposure, while the processor handles authorization and secure data transfer on the acquirer’s behalf.
The reason all four blur together is commercial. Square, Shopify Payments and Stripe fold every one of these roles into a single signup, so you experience one vendor where the plumbing still has four.
The Authorization Path, Step by Step
Authorization is the round trip that decides whether a sale goes through. It finishes in a couple of seconds, and it touches five separate organizations on the way.
Here is the path a card payment takes, based on Stripe’s own description of the processor flow:
- The shopper presents the card. A tap, dip or swipe at the terminal, or card details typed into a checkout page.
- The gateway encrypts and forwards. The checkout technology secures the card data and sends it to the processor.
- The processor packages the transaction. It formats the request and forwards it to your acquiring bank.
- The acquiring bank routes it to the card network. Visa, Mastercard or American Express takes the request onto its rails.
- The issuing bank decides. The shopper’s own bank checks the account, the available funds and its fraud rules, then approves or declines.
- The answer travels back the same chain. Issuer to network, network to acquirer, acquirer to processor, processor to the terminal or checkout page.
- The sale is captured and batched. Your system sends the day’s approved transactions to the processor at close of business.
- Settlement moves the money. Funds travel from the issuing bank into the merchant account, then out to your bank on its payout schedule.
Authorization and settlement are two different events, and confusing them causes real accounting problems. Authorization happens in real time and only reserves funds against the card. It confirms the card is good and the money is there.
Settlement is the slower half, landing in the merchant account a few business days after capture according to Stripe’s account of the flow. A sale that shows as approved on the terminal at 4pm is not cash in the bank that evening, which is why a store’s reported daily takings and its bank balance never line up on the same date.
What Processors Charge in 2026
Flat-rate providers publish their pricing, which makes them easy to compare. Rates below are the vendors’ own published figures as of August 2026, and processing rates change, so check the current page before budgeting.
| Provider | In person | Online | Keyed or card on file |
|---|---|---|---|
| Square (Free plan) | 2.6% + $0.15 | 3.3% + $0.30 | 3.5% + $0.15 |
| Square (Plus / Premium) | 2.5% + $0.15 / 2.4% + $0.15 | 2.9% + $0.30 | 3.5% + $0.15 |
| Shopify Payments | 2.6% + $0.10 Basic, 2.5% + $0.10 Grow, 2.4% + $0.10 Advanced | 2.5% to 2.9% + $0.30 across plans | Not published separately |
| SumUp | 2.6% + $0.10 | 3.5% + $0.15 | 3.5% + $0.15 |
Two patterns matter more than any single number. Card-not-present sales always cost more than card-present ones, at every provider on the list, because the processor and the issuing bank cannot confirm a physical card was there.
The second is that plan tier moves the rate. Square and Shopify Payments both cut the in-person percentage as the subscription goes up, so the monthly software fee and the processing rate have to be judged together rather than separately.
Full breakdowns of what each provider charges beyond the headline rate sit in Square’s POS pricing and fees, a full Shopify Payments review and the SumUp POS review.
Worked Example: What a $60 Sale Actually Costs
Take a store on Shopify’s Basic plan selling the same $60 item two ways, once across the counter and once through the website.
In person, at 2.6% + $0.10, the percentage comes to $1.56. Add the flat piece and the fee is $1.66, leaving the store $58.34.
Online, using the published range of 2.5% to 2.9% + $0.30, the fee lands somewhere between $1.80 and $2.04, leaving the store between $57.96 and $58.20.
The gap is small on one sale and stops being small at volume. A store selling through both channels has two effective processing rates, not one blended number, and any margin model built on a single average will drift as the channel mix moves.
Bundled Providers vs Separate Processor and Merchant Account
There are two ways to buy card acceptance, and the choice shapes everything from onboarding time to how much room you have to argue about price.
The bundled route puts a payment service provider in charge of the whole stack. Square, Shopify Payments and SumUp act as gateway, processor and account provider at once, publish one flat rate, and onboard you the same day. Support is one phone number, and the pricing is what it is.
The traditional stack separates the pieces. You contract a gateway, a processor and a merchant account at an acquiring bank, sometimes through three vendors, sometimes through a reseller that assembles them. Underwriting is manual, setup takes weeks, and the rate is negotiable.
- Bundled suits: new stores, low or seasonal volume, retailers who value getting trading this week over shaving basis points.
- Separate suits: steady high volume, unusual risk profiles, and any store where a sudden account pause would be catastrophic rather than annoying.
- Either way: you still need both a processor and an account, whether that shows up as one contract or three.
Bundled competitors worth putting side by side include Clover and PayPal Zettle, covered in the Clover POS review and the PayPal Zettle POS review.
Solutions That Handle Payment Processing
Square
Square bundles processor, gateway and merchant account into one account with published flat in-person and online rates by plan. The full rate card and hardware costs are in Square’s POS pricing.
Shopify Payments
Shopify Payments is the built-in processor for Shopify merchants, with plan-tiered in-person and online rates and no separate gateway needed. The full Shopify Payments review walks through setup and the costs.
SumUp
SumUp offers a flat-rate mobile card reader processor with a single published in-person rate of 2.6% + $0.10 and no monthly fee, aimed at small and mobile retailers. Check the SumUp POS review for the complete cost picture and hardware options.
Choosing a Processor as a Small Retailer
The headline rate is the easiest thing to compare and rarely the thing that decides the outcome.
- Channel mix: weight the in-person and online rates by how you actually sell, then compare the blended cost rather than the lowest advertised number.
- Payout timing: settlement speed, from 1 to 3 business days, affects cash flow, particularly for stores with tight working capital or seasonal spikes.
- Dispute handling: the fee per chargeback and the evidence window vary widely between providers.
- Hardware lock-in: terminals bought for one processor rarely work with another, so the switching cost is physical as well as contractual.
- Exit terms: a negotiated rate is worth little inside a contract that is expensive to leave.
Total cost per sale, not the advertised percentage, is the only comparison that survives contact with a real month of trading.
