Who this comparison is for
Growing SMBs at the inflection point where flat-rate stops being cheapest and interchange-plus begins to dominate.
Recommended processors for $25K–$50K monthly
The 4 processors below are the ones whose published rates, contract terms, and operator-side reputation hold up at this volume. Effective rates assume a normalized U.S. SMB card mix (60% credit, 40% debit, 30% rewards). See the methodology page for full assumptions.
1. Helcim
2.31–2.43% (interchange + 0.40–0.50%)Interchange-plusBest for
Primary recommendation at this tier. No monthly fee + automatic volume discounts above $25K = consistent winner.
Watch out for
No same-day deposit option. Underwriting requires balance sheet + P&L (1–2 week onboarding).
2. Stax (Fattmerchant)
2.21–2.45% (interchange + 0%–0.10%) + $99–$199/moSubscription IC-plusBest for
Above $35K monthly where the subscription fee amortizes out. Predictable subscription pricing for forecast-driven operators.
Watch out for
Below $35K monthly, the subscription kills the savings. Run the math at your actual volume before committing.
3. Stripe
2.88–2.95% onlineFlat-rate (negotiable above $80K)Best for
Custom checkout, marketplaces, subscription billing where Stripe's API ecosystem outweighs the 0.40%+ rate premium.
Watch out for
Pure cost-wise you are paying $140–$200/month more than Helcim at this tier. Justify via developer tooling, not rate.
4. Square
2.60–2.93%Flat-rateBest for
Card-present retail / restaurant where Square's free POS hardware ecosystem still beats the alternative cost of building one.
Watch out for
Online rate (2.93%) is uncompetitive at this volume. Move online traffic to Helcim or Stripe.
Pricing-model breakdown at $25K–$50K monthly
At $25K–$50K monthly monthly volume, three pricing models compete: flat-rate or auto-discount interchange-plus on the entry end, subscription interchange-plus in the middle, and custom IC++ contracts at the top. Here is the math on each.
Tier 1
Interchange-plus (no monthly)
Helcim
$0 monthly fee · Interchange + 0.40–0.50% + $0.08–$0.25 per transaction
Best for
$25K–$35K monthly. Best entry point to IC+.
What’s included
- ·No monthly fee or contract
- ·Auto-applied volume discounts
- ·Free virtual terminal
- ·Real interchange pass-through statements
- ·Best on math for the lower half of this tier
Tier 2
Subscription IC-plus
Stax / Payment Depot
$79–$199 monthly + Interchange + 0%–0.20% markup
Best for
$35K–$50K monthly. Subscription fee gets diluted at higher volumes.
What’s included
- ·Lowest per-transaction markup at this tier
- ·Premium support included
- ·Often free or discounted hardware
- ·Predictable monthly subscription
- ·Becomes the lowest-cost option above $35K
Tier 3
Custom IC++
Negotiated with an ISO
Varies — typically interchange + ~0.20–0.30% + $0.10 per transaction
Best for
$45K+ monthly with stable processing history and good chargeback ratio.
What’s included
- ·Lowest published-or-negotiated rate at this volume
- ·Custom contract terms (no auto-renewal, no ETF)
- ·Direct relationship with the underwriter
- ·Worth negotiating only if you process consistently
- ·Get quotes from 3 ISOs before signing
The actual math at $25K–$50K monthly
At $35,000 monthly with a 60/40 credit/debit mix and $80 average ticket, the comparison is: Stripe ≈ $1,030/month (2.94% effective). Helcim ≈ $830/month (2.37% effective). Stax ≈ $99/mo + $805 processing ≈ $904/month. Helcim wins by $130–$200/month over flat-rate. The break-even for Stax over Helcim sits around $50,000 monthly.
Sources
- myPayAdvisor 2026 Payment Processor Effective Rate Database — open dataset, CC-BY-4.0. View
- myPayAdvisor Research Methodology — card-mix assumption, sample selection, calculation method. View
- Federal Reserve Payments Study series — U.S. SMB card-mix distribution. federalreserve.gov
- Processor public pricing pages (captured 2026-04-30): Stripe, Square, Helcim, PayPal, Stax, Payment Depot, Adyen, Worldpay, Clover, Authorize.net, Braintree, Shopify Payments.