TL;DR
For mobile and on-the-go merchants processing under $30,000 a month, Square wins on hardware cost, next-day funding, and a free POS app. From $40,000 to $250,000 in monthly volume, Helcim's interchange-plus pricing saves 0.30 to 0.60 percent versus flat-rate plans. Stripe wins when the merchant runs a custom iOS or Android app and needs Tap to Pay with full API control. PayPal Zettle wins for sellers whose buyers already carry PayPal balances. Stax wins above $50,000 a month with commercial card volume.
How we ranked
We ranked six processors on the criteria a field merchant actually cares about, not a feature checklist.
- Effective rate at $50,000 monthly volume (30 percent). We modeled a 70 percent debit, 30 percent credit card mix using Visa and Mastercard published interchange.
- Hardware cost and portability (15 percent). Reader price, weight, battery life, and whether the device is tied to one processor.
- Funding speed (15 percent). Same-day, next-day, or T+2.
- Keyed and invoicing rate (15 percent). Mobile sellers often take card-not-present payments by phone or email.
- Offline acceptance (10 percent). Trade shows, basements, festivals.
- Contract length and exit cost (15 percent). Month-to-month beats multi-year leases with PCI fees.
Pricing figures come from each processor's public pricing page and the Visa and Mastercard interchange schedules. No estimates, no insider rates.
At a glance
| Provider | Headline pricing | Contract | Settlement | Best for | Watch out for |
|---|---|---|---|---|---|
| Square | 2.6% + $0.10 in person | Month-to-month | Next-day (instant 1.75%) | Under $30K/mo retail and service | Flat rate above interchange at higher volume |
| Stripe | 2.7% + $0.05 in person | Month-to-month | T+2 (instant 1.5%) | Custom mobile apps | Reserve policy is opaque |
| Helcim | IC + 0.40% + $0.08 in person | Month-to-month | T+2 standard | $25K to $250K mobile services | No offline mode |
| Clover | 2.3% to 2.6% + $0.10 + plan fee | Varies by reseller | Next-day | Existing Clover countertop users | Hardware locked to Fiserv |
| PayPal Zettle | 2.29% + $0.09 in person | Month-to-month | Instant to PayPal balance | PayPal-heavy buyer base | Sudden volume can trigger holds |
| Stax | $99/mo + IC + $0.08 in person | Month-to-month | T+2 standard | $50K+ mobile B2B | Breakeven near $30K/mo |
Square
Square charges 2.6 percent plus 10 cents per in-person tap, dip, or swipe through Square Reader or Square Terminal, per Square's published pricing. Keyed transactions are 3.5 percent plus 15 cents. Online checkout is 2.9 percent plus 30 cents. The basic POS app is free. A magstripe reader is free for the first device; the contactless Square Reader runs about $49.
Funding is next business day by default, with instant transfer at 1.75 percent per push. There is no monthly fee on the Free plan, and PCI compliance is bundled.
Square supports offline mode on iOS and Android for up to 72 hours, with transactions queued and processed once the device reconnects. The offline transactions are uninsured against decline above a configurable cap, so Square absorbs the chargeback risk only up to that ceiling.
Square fits mobile merchants under $30,000 a month who want one app for invoicing, in-person, and online without negotiation. Above $50,000 a month, the flat 2.6 percent plus 10 cents starts running 0.35 to 0.55 percent above interchange-plus on a typical card mix.
Stripe
Stripe's published rate is 2.7 percent plus 5 cents for in-person taps via Tap to Pay on iPhone and Tap to Pay on Android, and 2.9 percent plus 30 cents for online card payments. Keyed payments through a mobile reader are 2.7 percent plus 5 cents when EMV-completed.
There is no monthly platform fee. Stripe Reader S700 hardware is $349; the BBPOS WisePOS E is $249. Funding is T+2 by default in the U.S., with Instant Payouts at 1.5 percent (50 cent minimum) for eligible debit cards on file.
Stripe is the right pick when the merchant's mobile workflow is a custom iOS or Android app, not a stock POS. The SDK exposes interchange data, Level 2 fields, and dispute APIs that Square's POS does not. Volume-based pricing is available above $80,000 a month by request. Stripe does not fit a tradesman who just wants a reader and an invoice button.
Helcim
Helcim is the only interchange-plus processor on this list with publicly posted rates. Helcim's pricing page shows in-person at interchange plus 0.40 percent and 8 cents, online at interchange plus 0.50 percent and 25 cents, and keyed at interchange plus 0.50 percent and 25 cents. Automatic volume discounts kick in at $25,000, $50,000, $100,000, and $250,000 a month.
No monthly fee. No PCI fee. No contract or early termination fee. Helcim's Card Reader is $99. Funding is T+2 standard, with same-day available for $25 per batch.
Helcim does not support offline acceptance, so merchants who lose connectivity on a job site need a backup workflow. Helcim fits mobile service businesses, plumbers, electricians, mobile detailing, and mobile pet groomers above $25,000 a month who want statement transparency. Below $15,000 a month, Square's per-transaction savings beat the percentage spread.
Clover
Clover Go is Fiserv's mobile reader, paired with the Clover dashboard. Clover's published pricing shows in-person rates of 2.3 to 2.6 percent plus 10 cents depending on plan, and 3.5 percent plus 10 cents on keyed transactions. Monthly plans run $14.95 to $54.95.
The Clover Go reader is $49. The mobile app works with iOS and Android. Funding is next-day standard, with Rapid Deposit at 1 percent per instant transfer.
Clover's main caveat is hardware lock-in. Clover devices are tied to Fiserv processing. If a merchant later moves to a wholesale processor, the hardware is bricked. Rates also depend on which Fiserv reseller writes the contract: direct-from-Clover pricing is the floor, not the ceiling.
Clover Go fits merchants who already run a Clover countertop unit at a primary location and want to extend mobile coverage with the same back office. As a standalone mobile pick, the per-plan fees rarely pay back below $25,000 a month.
PayPal Zettle
PayPal Zettle is the mobile arm of PayPal's merchant stack. PayPal's published fees list in-person card payments at 2.29 percent plus 9 cents, keyed at 3.49 percent plus 9 cents, and PayPal QR-code payments at 2.29 percent plus 9 cents.
The Zettle reader is $29 for the first device, then $79. Funding to a PayPal balance is instant; transfers to a linked bank account are next business day. There is no monthly fee.
PayPal's appeal on mobile is the embedded buyer side. Tens of millions of U.S. consumers carry a PayPal balance per Nilson Report data, so adding PayPal as a checkout option on a mobile invoice can lift completion rates on service and B2B work.
PayPal Zettle fits sellers whose buyers already use PayPal and who want one balance for in-person and online activity.
Stax
Stax is the subscription-pricing option for mobile merchants who clear $50,000 a month. Stax's pricing starts at $99 a month plus interchange and 8 cents per in-person transaction, or 18 cents per online or keyed transaction.
There is no per-percentage markup. At $50,000 in monthly volume with 800 transactions, the all-in rate runs roughly 2.05 to 2.15 percent. At $100,000, the rate drops to 1.95 to 2.05 percent. Hardware sells separately, with mobile readers starting around $79.
Funding is T+2 standard. Stax supports Level 2 and Level 3 data, which trims interchange by 60 to 100 basis points on commercial card transactions per the Visa interchange schedule.
Stax fits mobile B2B verticals like wholesale food delivery, mobile equipment service, and commercial cleaning where commercial card acceptance is common and Level 2 data is worth the integration work.
Verdict
For mobile and on-the-go merchants under $30,000 a month, Square wins on hardware cost, next-day funding, and zero fixed fees. The 2.6 percent in-person rate runs above interchange-plus, but the breakeven on a Helcim or Stax statement does not arrive until $25,000 to $30,000 a month.
Between $40,000 and $250,000 a month, Helcim wins on transparency, volume discounts, and lack of contract. The 0.30 to 0.60 percent spread versus flat-rate compounds into $2,000 to $6,000 a year on $600,000 in volume, per the Federal Reserve's payment systems data on average ticket size and card mix for small business.
Stripe wins the developer-built mobile app case at 2.7 percent plus 5 cents in person. PayPal Zettle wins when buyers already use PayPal balances. Stax wins above $50,000 a month with commercial card volume. Clover Go is the right pick only when the merchant already runs Clover at a primary location.
