A merchant fee line looks like one number on an invoice, but it is built from two parts that behave differently: a percentage of the sale, and a fixed amount that stays the same no matter how big the sale is. The table below breaks that structure apart using Stripe, PayPal Checkout and Square's own published online-card rates as four worked examples, and adds a fifth column: the sale size at which the fixed part and the percentage part are contributing an equal number of cents to what the processor keeps. Below the table, the same three processors' surcharges for an international or a manually entered card are added in, each traced back to the source that states it.
| Percentage part | Fixed part | Fee on a $10 sale | Fee on a $1,000 sale | Sale size where the fixed part equals the percentage part | |
|---|---|---|---|---|---|
| Stripe, online card (Standard) | 2.9%1 | 30¢2 | $0.591 2 | $29.301 2 | $10.341 2 |
| PayPal Checkout | 3.49%5 | 0.49 USD6 | $0.845 6 | $35.395 6 | $14.045 6 |
| Square, online card (Free plan) | 3.3%8 | 30¢10 | $0.638 10 | $33.308 10 | $9.098 10 |
| Square, online card (Plus and Premium) | 2.9%9 | 30¢10 | $0.599 10 | $29.309 10 | $10.349 10 |
Each row is one processor's online card rate — Stripe's Standard plan, PayPal Checkout, and Square split into its Free plan and its Plus and Premium plans, because Square publishes two different percentages for the same kind of payment. The first two columns are the two numbers each processor actually publishes: a percentage part and a fixed part. The next two columns apply those two numbers to a $10 sale and a $1,000 sale, so the shape of the fee line is visible in dollars rather than only in percent. The last column answers a question none of the three pricing pages answers directly: at what sale size the percentage part and the fixed part take an equal-sized bite.
Every fee line compared here needs both a percentage part and a fixed part to be complete — Stripe's 2.9% on its own does not describe what a sale costs to process, and neither does its 30¢ fixed fee on its own; the fee line is the sum of both, applied to that one sale. PayPal's fee line works the same way, at 3.49% plus a 0.49 USD fixed fee, and so does Square's, at 3.3% on the Free plan or 2.9% on Plus and Premium, plus a 30¢ fixed fee either way. Some fee lines add a third part on top of these two, but only when a specific condition is met, not on every sale — that third part is covered separately below, because it is conditional rather than structural.
The last column in the table above names a single sale size for each fee line: the point at which the fixed part and the percentage part are contributing the same number of cents. Below that sale size, the fixed part is the larger of the two; above it, the percentage part takes over as the larger contributor, and keeps growing while the fixed part stays flat. A fee line with a lower percentage but the same fixed fee crosses that point at a larger sale size than a fee line with a higher percentage — which is exactly why comparing only the headline percentage, or only the fixed fee, tells an incomplete story on a small sale and a complete-enough one on a large sale.
Stripe and Square both add 1.5% to their standard rate when a card was issued outside the United States, applying that surcharge the same way at every sale size. PayPal adds 1.50% on top of its domestic rate for a different condition — an international commercial transaction, which PayPal defines by the transaction rather than by where the card was issued. Stripe separately adds 0.5% to its standard rate for a card that is typed in by hand instead of entered by the customer online or tapped in person; PayPal and Square's keyed-in rates are left out of the comparison above.
A merchant fee line has two parts: a percentage of the sale, and a fixed amount that stays the same no matter how large the sale is. Stripe charges 2.9% plus 30¢ on a domestic online card payment, PayPal Checkout charges 3.49% plus a 0.49 USD fixed fee, and Square charges 3.3% on its Free plan or 2.9% on Plus and Premium, both plus a 30¢ fixed fee. Some fee lines add a third element on top of these two — a surcharge that only applies under a specific condition, such as a card issued outside the United States.
Because the fixed part of a fee line does not shrink as the sale grows, while the percentage part scales with it. Take Stripe's rate as an example: on a $10 sale Stripe keeps $0.59, and the 30¢ fixed fee is more than half of that. On a $1,000 sale the same rate keeps $29.30, and that same 30¢ fixed fee is now a sliver of the total. The percentage part grows with the sale; the fixed part never does, so it matters most exactly when the sale is small.
Yes, on all three processors compared here. Stripe adds 1.5% to its standard rate for cards issued outside the United States, PayPal adds 1.50% on top of its domestic rate for international commercial transactions, and Square adds 1.5% for cards issued outside the United States across its Free, Plus and Premium plans alike.
Not quite. Stripe's fixed fee and Square's fixed fee are both 30¢, and Square charges that same 30¢ on its Free plan as well as on Plus and Premium — so three of the four fee lines compared here share one fixed part. PayPal's fixed fee is different: 0.49 USD on a domestic commercial transaction, not 30¢.
Gathered with AI assistance; every figure was checked against the linked provider page and signed off by Seonrye Kim.