How each model works
Flat-rate pricing charges one percentage plus a fixed amount on every sale, whatever card the customer uses. Square's free plan, for example, charges 2.6% plus 15 cents in person and 3.3% plus 30 cents online. The provider pays interchange out of that and keeps the rest.
Interchange-plus pricing passes the actual interchange and network fees for each card through to you, then adds the processor's markup on top. A debit card costs you less than a premium rewards card, because it costs less to accept. On Swipe Saver's Premium plan the "plus" isn't a percentage at all: it's one flat monthly membership of $25, $50 or $99 depending on your volume.
A worked example: $25,000 a month in person
A café processing $25,000 a month in card sales, with an average sale of $40, runs about 625 transactions.
| Flat rate (2.6% + $0.15) | Interchange-plus (Swipe Saver Premium) | |
|---|---|---|
| Percentage | $650.00 | $447.50 (interchange at about 1.79%) |
| Per transaction | $93.75 | $50.00 (about $0.08 each) |
| Membership | None | $99.00 |
| Monthly total | $743.75 (2.97%) | $596.50 (2.39%) |
That's $147.25 a month, or about $1,767 a year, for the same sales. The interchange figure is a typical 2026 effective rate for Visa, Mastercard and Discover in person, which includes a small processor markup, so the real difference is usually a little larger.
Online: $9,000 a month
An online store selling $9,000 a month at a $60 average sale runs about 150 orders. At 3.3% plus 30 cents, a flat rate costs $342.00 (3.80%). Interchange at a typical online rate of about 2.31% plus 25 cents, plus a $50 membership, comes to $295.40 (3.28%): $46.60 a month less.
When flat rate wins
A fixed membership is a bigger share of a small total. At $1,500 a month, the same café math gives $44.62 on a flat rate against $54.85 on Premium, so the flat rate is about $10 cheaper. The crossover sits at roughly $2,500 a month in card sales. Right at the start of each membership tier, around $5,000 and $10,000, the two models come out close; above that, interchange-plus pulls ahead quickly.
So if you're just starting out, a flat rate is a fine choice. Once you're past a few thousand dollars a month, it's worth running your own numbers.
MONTHLY COST, IN PERSON, $40 SALE
$1,500 FLAT / PREMIUM44.62 / 54.85
$5,000 FLAT / PREMIUM148.75 / 149.50
$25,000 FLAT / PREMIUM743.75 / 596.50
What about tiered pricing?
Many processors sell a third model: tiered pricing, with "qualified", "mid-qualified" and "non-qualified" rates. The low qualified rate is the one you're quoted; rewards, business and keyed-in cards fall into the higher tiers. Because you can't see what interchange each card actually cost, tiered pricing is the hardest to compare. If your statement has those three words on it, read our guide to statement fees.
Why the pricing model matters more in 2027
A proposed Visa and Mastercard settlement, given preliminary approval in June 2026 with a final hearing set for November 16, 2026, would lower average interchange by 0.1 percentage point for five years and cap standard consumer credit card interchange at 1.25%. On interchange-plus pricing, a cut like that shows up on your statement automatically. On a flat rate, it only reaches you if the provider decides to lower its rate.
Run your own numbers
Two figures from your statement are enough: monthly card volume and total fees. The Swipe Saver calculator prices Premium, Hybrid and Zero against what you pay now, and the rate report card grades what you pay now in about 30 seconds.
Sources: NerdWallet, Square fees (updated March 2026); The Motley Fool, average processing fees (Helcim data); Merchant Services of America on the settlement, October 2026. Examples use Swipe Saver's published membership tiers.