Hidden payment processor fees

The 2.9% + $0.30 headline rate is honest, but it's not the whole story. Here's every real-world fee that can land on a transaction — by processor — and when to expect it.

Chargeback / dispute fees

When a customer disputes a charge through their card issuer, the processor charges you a fee on top of refunding the money. This is the single most variable cost across processors:

Square absorbs dispute fees via Seller Protection (up to $250/month). That's a real differentiator for high-dispute categories — subscriptions, digital goods, event tickets. If you process $100K+/year in high-dispute categories, Square's no-fee policy can save hundreds per month versus Stripe or PayPal.

Refund fee quirks

When you refund a transaction, what happens to the original fee? Not all processors treat this the same way:

• Stripe: Most accounts get the full fee refunded (both the 2.9% and the $0.30). Older accounts may only refund the percentage.
• Square: Full fee refunded.
• PayPal: Keeps the fixed fee ($0.49). Only the percentage is refunded. This is a real drag for high-refund businesses.
• Shopify: Full fee refunded on Shopify Payments.

PayPal's policy here dates to 2019. If your refund rate is 5%+ and you're using PayPal, you're eating an extra $0.49 per refunded transaction — $50 on 100 refunds, $500 on 1,000. That adds up.

International card surcharges

When a non-US card is used to pay a US merchant, processors add a surcharge:

Square's international card support is limited — they're primarily a domestic processor in each country they operate. If you sell cross-border from the US, Stripe (best international) or Shopify (decent) are better picks. PayPal handles international but at a premium.

Currency conversion fees

When the payment currency differs from your settlement currency, there's a conversion markup:

• Stripe: +1% on top of the exchange rate
• PayPal: ~4% on top (highest by a wide margin)
• Shopify: +2% on top
• Square: Not applicable for most US merchants

For cross-border SaaS, PayPal's 4% currency conversion is the quiet killer. A European customer paying €100 that converts to USD loses ~€4 to PayPal on top of the international surcharge and base rate. Total: ~9% on that transaction.

Keyed / card-not-present penalty

Typing a card number manually (vs. swiping, dipping, or tapping in person) triggers higher rates because card networks flag it as higher-risk:

• Square: 3.5% + $0.15 (up from 2.6% + $0.10 for card-present)
• Stripe: No separate keyed rate for online — but in-person via Terminal is 2.7% + $0.05 vs online 2.9% + $0.30
• PayPal Here / Zettle: Has separate keyed rates; varies by region
• Shopify POS: Matches Square's logic — keyed is more expensive than card-present

If you take phone orders or mail orders where you type in the card, factor the keyed rate into your pricing. It's meaningfully more expensive than card-present.

Instant payout fees

Standard payouts are free on every major processor (typically 1–3 business days). But if you need money today, there's a premium:

For cash-flow-tight businesses instant payouts are lifesavers; for everyone else, the free next-day payout is fine.

Third-party gateway penalties (Shopify only)

If you use Shopify's storefront with a non-Shopify-Payments gateway (e.g., Stripe, Authorize.net), Shopify adds an extra transaction fee on top of the gateway's own rate:

• Basic plan: +2%
• Shopify plan: +1%
• Advanced: +0.5%
• Plus: negotiable

Using Stripe through Shopify's Basic plan: you pay Stripe's 2.9% + $0.30 plus Shopify's 2% penalty = 4.9% + $0.30. Rarely worth it. Just use Shopify Payments.

Hardware and monthly fees

Pure online processors (Stripe, PayPal Checkout) have no hardware or monthly fees. In-person ecosystems do:

• Square hardware: Free magstripe Reader, $49 contactless Reader, $299 Stand, $1,099 Register. No monthly fee on base plan.
• Shopify: $5–$399/month subscription required for a real store.
• Stripe Terminal: $59 Reader M2, $349 BBPOS WisePOS E. No monthly fee on standard accounts.
• PayPal Zettle: $29 card reader. No monthly fee on base.

Monthly minimums and account fees

None of Stripe, Square, PayPal (standard), or Shopify Payments charge a monthly minimum transaction fee. This is a big win over traditional merchant accounts (which can charge $25+/month if you don't hit minimums). The modern processor model is pure per-transaction pricing.

Exception: Shopify's monthly subscription ($5–$399) is effectively a minimum. You pay it whether you process $1 or $100,000.

Invoicing & subscription add-ons

Each processor has optional paid products that sit on top of basic processing:

• Stripe Invoicing: 2.9% + $0.30 + 0.4% extra per paid invoice (for Advanced features). Light Invoicing is free.
• Stripe Billing / subscriptions: 0.4% of recurring charges (Basic) or 0.8% (Advanced).
• Square Invoices: 3.3% + $0.30 (no extra charge over card).
• PayPal Invoicing: 3.49% + $0.49 (same as Checkout).

Stripe's Billing pricing for subscriptions can surprise SaaS founders. A subscription business running through Stripe Billing Advanced pays 2.9% + $0.30 + 0.8% = effectively 3.7% + $0.30. Still reasonable; just know about it.

Radar / fraud protection

Basic fraud screening is included on every major processor. The paid tiers offer custom rules and manual review:

• Stripe Radar for Fraud Teams: $0.05 per screened charge
• Square Seller Protection: Free (covers up to $250/month in disputes)
• PayPal Seller Protection: Free on qualifying transactions
• Shopify Fraud Analysis: Free (basic), $9+ for Shopify Fraud Control

Holds on new accounts

This one's not a fee, but it hits cash flow the same way. New accounts often have rolling reserves or delayed payouts:

• Stripe: 7-day rolling reserve on new accounts, released after history builds.
• Square: Typically no holds for low-risk verticals; risk-score-driven.
• PayPal: Notorious for 21-day holds on first ~$2K–$5K. Plan cash flow accordingly.
• Shopify Payments: 3-day rolling reserve on new accounts.

If you need immediate access to revenue, PayPal's holds are a real planning constraint for new merchants.

The real "all-in" cost

Headline rates are useful for comparison but your actual cost depends on the mix of scenarios in your business. For most merchants, realistic all-in cost of processing is:

• Domestic US online e-commerce, low dispute: ~2.9–3.2% + $0.30 (close to headline)
• International SaaS with currency conversion: ~5.5–9% + $0.30 depending on processor mix
• B2B invoicing where you can push to ACH: ~1% effective (huge win over card)
• Subscription with refunds & disputes: 3.5–4.5% effective, heavily dependent on processor choice (PayPal worst, Square best on dispute costs)

Running your own numbers

The calculators on netfee.io model all of the above. If you want to see what any specific scenario costs — including international, currency conversion, ACH, micropayments, and keyed — run it through the head-to-head comparison or the individual processor calculators:

• Stripe fee calculator
• Square fee calculator
• PayPal fee calculator
• Shopify fee calculator
• Head-to-head: Stripe vs Square vs PayPal