Payment processing fees for a US small business typically run between 2.6% and 2.99% of the transaction value, plus 10 to 49 cents per transaction, depending on the processor and the card type.
On a $100 invoice, the fee range is $2.79 to $3.49.
ACH transfers run $0 to 1.5% depending on the processor.
The right question isn’t which is cheapest in isolation; it’s which fee model wins at your actual card mix and volume.
Run a quick stress-test: if your business takes 70% debit cards and 30% credit cards, flat-rate pricing usually loses to interchange-plus pricing above $10,000/month in volume. If your business takes 70% rewards credit cards and 30% debit, flat-rate pricing is competitive up to $50,000/month. Most small businesses underestimate the per-card-type variation, then overpay on volume that should be cheaper.
Payment processing fees are percentage of transaction value plus a small fixed fee per transaction. Pick flat-rate for simplicity under $10k/month; switch to interchange-plus or subscription pricing above that, but only after running the volume math at your actual card mix.
Key facts: The effective cost of card processing for a small business breaks into interchange (set by card network), assessment (set by network), and processor markup (the variable).
Flat-rate processors (Stripe, Square, PayPal) charge $0.50-$0.70 effective markup on top of interchange plus assessment.
Interchange-plus processors (Stax, Payment Depot, Helcim) charge $0.25-$0.50 markup.
ACH transfers run $0 (Square ACH to bank account with 1-2 day ACH, free) to $5 (Stripe ACH, 0.8% capped at $5).
International cards add 1.5%-2.0% cross-border fee on top of base rate.
At $10k/month on a 70/30 debit/credit card mix: Stripe charges about $300. Stax interchange-plus charges about $240. The savings at $50k/month grow to $300-$400/month with Stax. At $5k/month and below, the savings are under $20 and switching costs often exceed them.
What each fee component actually pays for
The fee shown on your statement reflects three parties: the card network, the issuing bank, and the processor.
Interchange. The bulk of the fee, paid to the issuing bank (the customer’s bank). Set by the card network (Visa, Mastercard) within regulatory bounds. Varies dramatically by card type: debit cards interchange as low as $0.05 + 0.05% (Durbin-capped); consumer credit interchange at 1.43% + $0.10; rewards at 1.65% + $0.10; premium rewards at 2.45% + $0.10; business cards at 1.85%-2.95%.
Assessment. A flat-ish percentage (0.13%-0.15% for Visa, 0.13% for Mastercard, 0.15% for Amex) paid to the card network. Set by the network.
Processor markup. The only part the processor controls. Flat-rate processors roll the markup into a single percentage that covers interchange + assessment + markup for all card types. Interchange-plus processors publish the underlying interchange and add their markup ($0.25-$0.50 per transaction) above it.
Flat-rate pricing: the canonical US small business option
Stripe, Square, and PayPal are the canonical flat-rate processors for US small business. Their published fee is what they bill on every approved transaction, regardless of card type.
| Plan | Online rate | In-person rate | ACH fee | International |
|---|---|---|---|---|
| Stripe Standard | 2.9% + 30 cents | 2.7% + 5 cents (Stripe Terminal) | 0.8% capped at $5 | +1.5% (cross-border) + 1% (currency conversion if applicable) |
| Square Standard | 2.9% + 30 cents | 2.6% + 10 cents | 0% for standard deposits (1-2 business days), 1.5% for Instant Deposit | +1.5% (international cards) |
| PayPal Commerce | 2.99% + 49 cents (PayPal Checkout) | Not directly supported; Zettle for in-store | 2.9% + 30 cents (PayPal Pay Later / ACH invoice) | +1.5% (international) |
For the detailed 3-way comparison of these three on the dimensions of API, ease of setup, and consumer trust at checkout, the stripe vs square vs paypal page covers the practical difference. For how the pricing model itself works (flat-rate vs interchange-plus vs subscription), the how payment processors work page has the structural breakdown.
Interchange-plus pricing: cheaper above $10k/month, variable
Interchange-plus (IC+) processors (Stax, Payment Depot, Helcim) charge a smaller markup on top of true interchange + assessment. The effective rate tracks your actual card mix; the markup is fixed at $0.25-$0.50 per transaction.
For a business processing $50,000/month with a 70/30 debit/credit mix, the math is:
| Cost component | Stripe Standard | Stax interchange-plus | Difference |
|---|---|---|---|
| Effective rate (70/30 mix) | ~3.05% (rate + per-transaction spread on mixed card types) | ~2.20% (true IC+ ~1.95% + 0.25% markup) | 0.85% |
| Per-transaction fixed | 30 cents | 25-50 cents | small |
| Monthly total at $50k | ~$1,560 | ~$1,225 | ~$335/month savings |
At $200k/month, the gap widens to about $1,500/month savings with interchange-plus. At $5k/month, the gap is under $30/month and the operational overhead of switching doesn’t justify it.
The fees that don’t appear on your statement
Beyond the percentage rate and per-transaction fixed fee, processors charge for several line items that don’t show up in the headline rate.
Chargeback fee. $15-$25 per chargeback regardless of outcome. Charged even when the merchant wins the dispute. The processor views this as the cost of filing the dispute on your behalf; the network view is the issuer-funded chargeback with merchant-funded response fees.
PCI compliance fee. Most flat-rate processors absorb PCI compliance scope into their SAQ-A validation flow; some interchange-plus processors charge a separate $50-$300/year fee for the annual PCI compliance questionnaire and audit work. Confirm before signing.
Gateway fee. Flat-rate processors (Stripe, Square, PayPal) bundle the gateway into their rate. If you’re on an interchange-plus processor and connect your merchant account to a separate gateway (Authorize.Net, NMI), expect $10-$30/month for the gateway subscription plus per-transaction fees of $0.05-$0.20.
Early termination fee. Most processors don’t have one (Stripe, Square, PayPal all signed without early termination clauses). Some interchange-plus processors include a 12-24 month commitment with an ETF of $200-$500. Read the agreement.
Reserve holdback. Not a fee per se, but a percentage of your processing volume held against chargeback risk for 6-180 days. Triggered by high chargeback rate, AML flags, or specific MCC categories.
Cross-border / international cards. +1.5% per transaction on a card issued outside the US. Multi-currency conversion adds another 1% if the customer’s currency differs from your settlement currency.
Invoice / refund processing fee. Some processors charge a refund fee ($0-$15 per refund) to discourage refund initiation. Stripe and Square do not charge refund fees; PayPal does charge a $0.30 refund fee on personal accounts (waived on business accounts).
ACH transfer fees: the alternative for large invoices
ACH is materially cheaper than cards for invoices over $500 because the fee is a small percentage (or capped at a small flat dollar), not a percentage-of-invoice-value fee.
Stripe ACH at 0.8% capped at $5. Best for SMB ACH transfers at typical invoice volumes ($100-$2,000). On a $625 invoice, the fee is $5 (the cap). On a $1,000 invoice, the fee is $5 (the cap). On a $100 invoice, the fee is $0.80.
Square ACH at 0% for standard deposits. Free for cash flow you can wait 1-2 business days on. 1.5% fee for Instant Deposit (cash in minutes).
PayPal ACH (Pay Later and invoice link). 2.9% + 30 cents under the standard commerce rate. Effectively the same as cards; ACH on PayPal doesn’t save money.
Dwolla (ACH-first API). 0.5% per transfer capped at $5. Most aggressive rate for ACH-first use cases; requires more developer effort than Stripe.
For most small businesses, ACH is the right answer for invoices over $1,000 (where the card fee is $30-$50); card is the right answer for transactions under $500. The processor that supports both at reasonable rates (Stripe) is the most flexible.
Subscription pricing: the predictable-cost alternative above $50k/month
Subscription pricing (Payment Depot $99/month flat with $0 per-transaction; Helcim and Stax at lower monthly fees plus per-transaction) is the right tier above $50k/month for businesses that want a fully predictable monthly bill.
At $50k/month, Payment Depot’s $99 subscription + $0 per transaction saves about $1,150/month vs Stripe Standard. Subscription pricing generally requires a written commitment (12-24 months) and may have an early termination fee.
The breakeven is roughly $30,000-$50,000/month: below that, flat-rate wins on simplicity; above that, subscription (or interchange-plus) wins on cost.
What the headline rate hides
Three recurring traps at the fee decision.
Trap 1: “starting at” headline rate is the entry rate. Stripe Standard is 2.9% + 30 cents. At higher volume, Stripe offers custom rates through annual contracts. The negotiated rate (often 2.6% + 30 cents, or 2.4% + 30 cents at $1M+/month) is not the headline rate but is what large businesses actually pay.
Trap 2: international card surcharge adds 1.5%. A US ecommerce business selling to customers in the EU has effectively 4.4% + 30 cents in fees for those cards. Factor this in when pricing for international markets.
Trap 3: chargeback rate threshold triggers reserve or termination. Visa and Mastercard thresholds are 0.9% chargeback rate over 100 monthly transactions; exceeding puts you on a monitoring list. Above 1.8% rate is automatic enrolled in the dispute-tracking program. Above ~2.5% rate, expect processor-initiated reserve or account termination. Track chargebacks monthly.
Pick the pricing model that wins at your volume
The decision follows three rules of thumb.
Pick flat-rate (Stripe, Square, PayPal) if your volume is under $10k/month and you want one predictable fee in the dashboard.
Pick interchange-plus (Stax, Payment Depot, Helcim) if your volume is $10k-$50k/month and your card mix is dominated by debit and low-cost credit cards.
Pick subscription pricing (Payment Depot $99/month, Helcim $0/month with interchange-plus markup) if your volume is over $50k/month and you want a fully predictable monthly bill.
For the cost math at each tier and the processor comparison, the best payment processor for small business comparison goes through Stripe, Square, PayPal, Stax, and Helcim at each volume tier.
For the definitional line between processor and gateway and when each matters for ecommerce vs in-person, the payment processor vs payment gateway page covers the structural distinction.
For the practical difference between flat-rate leaders on the dimensions of API, ease of setup, and consumer trust, the stripe vs square vs paypal page runs the 3-way comparison.
For the cost math specifically in the ecommerce context where chargeback rate is higher and international cards add 1.5 percent the payment processor for ecommerce page covers the ecommerce specific factors.
Last updated: October 2026
