Payment processor fee comparison calculator

Processor fees — the line your CFO doesn't read

For a $1.2M/year merchant: 0.3% in processor fees is $3,600. The difference between Stripe (2.9%) and Adyen (~2.3% effective on US SaaS) is $7,200/year. At $10M+ volume, processor selection becomes a real P&L line.

What "2.9% + $0.30" actually costs

effective rate = (volume × pct) + (txn count × per-txn) ÷ volume

For a $80 AOV merchant, the $0.30 fee adds 0.375% to the effective rate. At $20 AOV it's 1.5%. Per-transaction fees disproportionately hurt low-AOV businesses.

When each processor wins

• Stripe — best for sub-$5M volume, US-centric, want fast onboarding. Worse on international, worse on Amex than tier-1 alternatives at scale.
• Square — best for in-person retail, high transaction count, US-only. The lower per-txn fee ($0.10) makes a real difference for sub-$30 AOV.
• PayPal Commerce — only choose if you need PayPal-as-payment-method. Higher fees, worse risk holds, slower payouts. Brand-recognition value real for B2C.
• Adyen — best for $10M+ international merchants. Interchange-plus pricing means you pay actual cost + small markup; opaque at low volume but transparent at scale.
• Interchange-plus direct — for $50M+ merchants who can negotiate. Saves 30-50 bps vs Stripe but requires PCI compliance, gateway integration, and ops overhead.

Hidden costs

• Refund fees — Stripe doesn't refund the per-txn $0.30 on returns. Real cost when refund rate >5%.
• International cards — 1-1.5% extra. International e-commerce should explicitly model intl % to avoid surprise.
• Currency conversion — 1-2% on top of processor fee for FX merchant pricing. Stripe: 1%. Adyen: ~0.5%.
• Chargeback fees — $15-25 per chargeback, often only refunded on a successful dispute. Lost-cause merchandise is a separate cost.
• Tier monitoring programs — over 1% chargeback rate puts you on Visa/MC monitoring. Punitive fees ($25k+ in extreme cases).

When to negotiate

• $1M+ monthly volume: ask for 0.1-0.3% discount
• $5M+: move to interchange-plus pricing
• $20M+: solicit RFPs from 2-3 acquirers, negotiate hard
• High-margin / low-risk vertical: get 30-50 bps off standard rates
• High-risk vertical (CBD, supplements, subscription billing): expect 4-8% rates