Stax (formerly Fattmerchant)
- Stax's volume bands are annual, not monthly. $99 a month covers up to $150,000 per year. $139 covers $150,000 to $250,000 per year. $199+ covers $250,000 a year and up. A shop doing $20,000 a month is $240,000 a year. That's the $139 tier, not a custom quote.
- Stax charges no percentage markup at all. You pay interchange, plus 8 cents card-present or 15 cents online, plus the monthly subscription.
- Stax passes flat rate early and passes Helcim late. Those are two different numbers. At a $50 average ticket, Stax beats Square's Free plan from about $7,300 a month card-present and about $5,600 online. Helcim takes far longer. Card-present it never happens at a volume where Stax still publishes its price.
- Above $250,000 a year, Stax's subscription is published only as "$199+". There's no ceiling on it. This site won't rank a processor on a price with a plus sign in it. So every verdict below stops at $250,000 a year.
- The subscription is the catch. You pay it in a dead month. That makes Stax a poor fit for seasonal businesses.
- Stax doesn't publish a base chargeback fee. It sells optional chargeback protection at $25 per chargeback. Compare Helcim, which charges $0 when you win.
Stax charges a monthly subscription. Then it passes interchange through at cost with zero percentage markup. That model wins in a narrow band. The conditions matter more than the headline.
Every Stax fee on this page was read from staxpayments.com/pricing on 2 August 2026.
Every comparison uses the interchange assumption published at How We Compare Processor Costs. That's 1.03% + $0.178 card-present and 1.50% + $0.172 online, pass-through including an assumed 0.14% + $0.02 in network assessments. The assumption is load-bearing here. Stax pays interchange visibly and a flat-rate processor pays it invisibly. Change the assumption and these crossovers move.
When to Use Stax
Stax is worth pricing if:
- You're online with a low average ticket, roughly $25, and doing $11,000 to $20,800 a month. That's the narrow window where Stax is genuinely the cheapest option this site can rank.
- Your annual volume is under $250,000. Then the subscription you'd pay is a published number rather than "$199+".
- You want to shop the whole market, not just leave flat rate. Stax passes Square's Free plan from about $5,600 a month online and $7,300 card-present at a $50 ticket. It passes PayPal Zettle card-present from about $10,700 at the same ticket. At a $15 card-present ticket, no volume gets Stax past Zettle with a published subscription price.
- Your volume is steady enough that a fixed subscription is an advantage, not a risk.
- You want invoicing, a virtual terminal and analytics bundled.
Skip Stax if:
- You're card-present. Helcim's markup is lower at every volume where Stax publishes a price. Helcim charges the same 8 cents and no subscription in its entry band.
- Your volume is below the flat-rate breakeven, or seasonal, or unpredictable.
- You have real dispute volume and want a processor that doesn't charge you for winning.
- You need advanced developer tooling.
- You're primarily card-present retail and want a full POS. Square or Clover is better.
Pricing Breakdown
Subscription Tiers
| Annual processing volume | Monthly subscription |
|---|---|
| Up to $150,000 per year | $99 |
| $150,000 - $250,000 per year | $139 |
| $250,000 per year and above | $199+ |
Stax's own wording: "Subscription prices are determined by processing volume and do not include cents per transaction."
Source: staxpayments.com/pricing, verified 2 August 2026.
Present annual bands as monthly and you overstate Stax's cost roughly twelvefold. A merchant doing $20,000 a month looks like a $240,000-a-month enterprise account needing custom pricing. They're a $240,000-a-year business, sitting squarely in the $139 tier. That one mistake points people away from a processor they should at least have priced.
Read anywhere that Stax's $99 plan is for "$8K to $50K a month"? Same error. $99 covers up to $150,000 a year. That's about $12,500 a month.
Now the contrast. Helcim's bands are labelled "monthly credit card volume" and really are monthly. Compare the two tables without checking the period and you get this wrong. Correcting it doesn't make Stax the cheapest option. It makes Stax worth pricing.
Per-Transaction Fees
| Transaction Type | Cost |
|---|---|
| Card-present | Interchange + 0% markup + $0.08 |
| Online / card-not-present | Interchange + 0% markup + $0.15 |
| Keyed-in | Billed as card-not-present: interchange + $0.15 |
Source: staxpayments.com/pricing, verified 2 August 2026.
The zero is the point. Every other processor on this site takes a percentage of every transaction on top of interchange. Stax doesn't. That's why its cost curve flattens as volume grows. The subscription is what you pay for that. It's also why the model needs volume before it works.
Disputes
| Item | What Stax publishes |
|---|---|
| Base chargeback fee | Not published |
| Chargeback protection add-on | Optional, $25 per chargeback |
Stax's pricing page sells optional chargeback protection at $25 per chargeback. It never says what a chargeback costs without the add-on.
Ask, in writing. What does a chargeback cost on the base plan? Is the fee refunded on a win? What exactly does the $25 protection cover? For comparison, Helcim publishes $0 for a chargeback resolved in your favour and $15 if you lose.
What Is Not Published
| Item | Status |
|---|---|
| Base chargeback fee | Not published |
| Instant payout / next-day funding | Not published |
| ACH rate | Not published on the pricing page. The 0.5% + $0.25 capped at $6 that gets attached to Stax is Helcim's published ACH rate, not Stax's |
| Volume floor | Not published |
| What "$199+" becomes at high volume | Not published. The plus sign is unbounded, and it starts at $250,000 a year, which is a volume plenty of ordinary SMBs pass |
| Hardware prices | Not part of this verification pass |
| Contract length and termination terms | Not published |
$250,000 a year is $20,833 a month. Above that, Stax's published price carries a plus sign. A plus sign isn't a price.
Every crossover below that falls above the line is computed at the $199 floor. Floors are the friendliest possible assumption for Stax. Treat them as the earliest point at which Stax could win, not as a claim that it does. Above $250,000 a year, get your actual subscription in writing before you model anything.
Two Different Breakevens, and They Get Confused
Stax has to clear two separate hurdles. The first gets reported as though it were the second.
- The flat-rate breakeven. The volume at which Stax beats Square, PayPal, or Braintree. This is low, around $5,600 to $12,000 a month.
- The Helcim breakeven. The volume at which Stax becomes the cheapest option this site can rank. Much higher. Card-present, it sits above the point where Stax stops publishing a price.
Print the first number as though it answered the second question and you've sent someone to the wrong processor. Between the two, Helcim is cheaper than Stax.
Breakeven 1: Stax against flat rate
Stax pays interchange visibly. A flat-rate processor buries it in the headline rate. So the comparison needs the pass-through assumption. That's 1.03% + $0.178 card-present and 1.50% + $0.172 online.
Against Square's Free plan, card-present, at a $50 average ticket:
Stax = 99 + (0.0103 x volume) + (0.178 + 0.08) x transactions
Square = (0.026 x volume) + (0.15 x transactions)
At a $50 ticket, transactions = volume / 50, so:
Stax = 99 + 0.0103 x volume + 0.00516 x volume = 99 + 0.01546 x volume
Square = 0.026 x volume + 0.003 x volume = 0.029 x volume
They meet at volume = $99 / 0.01354 = about $7,300 a month. Annualised that's $88,000. Inside the $99 tier, so the tier holds at the crossover.
Against Square's Free plan, online, at a $50 average ticket:
Stax = 99 + 0.0150 x volume + 0.00644 x volume = 99 + 0.02144 x volume
Square = 0.033 x volume + 0.006 x volume = 0.039 x volume
They meet at about $5,600 a month, or $68,000 a year. Also inside the $99 tier.
| Flat-rate comparison, $50 ticket | Stax passes it at |
|---|---|
| Square Free, online (3.3% + $0.30) | about $5,600/month |
| Stripe, online (2.9% + $0.30) | about $7,300/month |
| Braintree, online (2.89% + $0.29) | about $7,500/month |
| Square Free, card-present (2.6% + $0.15) | about $7,300/month |
| Stripe Terminal, card-present (2.7% + $0.05) | about $7,900/month |
| PayPal Zettle, card-present (2.29% + $0.09) | about $10,700/month |
All on the $99 tier, all consistent with that tier at the crossover volume.
Ticket size moves these, and not in the direction you'd guess. Stax's total fixed charge per transaction is higher than Square's in both channels. It's 25.8 cents against 15 cents card-present, 32.2 cents against 30 cents online. A bigger ticket means fewer transactions. That helps Stax. So the flat-rate breakeven falls as your ticket rises. Card-present against Square Free it's about $11,600 a month at a $15 ticket, $7,300 at $50, and $6,600 at $150.
Breakeven 2: Stax against Helcim
This is the one that decides anything. Helcim charges no monthly fee, and it's cheaper than every flat rate this site ranks above roughly a $9 ticket. Interchange is identical on both sides, so only the markup matters.
Card-present, Helcim's entry band charges 0.40% + $0.08. Stax charges 0% + $0.08 plus a subscription. The 8 cents is identical. So the whole comparison is Helcim's 0.40% against Stax's subscription. Stax wins when:
subscription < 0.0040 x volume
At $99 that needs $24,750 a month, or $297,000 a year. That isn't the $99 tier. At $139 it needs $34,750 a month, or $417,000 a year. Not the $139 tier either. The first internally consistent answer is the $199 floor at about $49,750 a month. That's $597,000 a year, deep inside the unpublished "$199+" band.
So card-present, no volume gets Stax past Helcim while Stax's subscription price is still published. That verdict holds at a $15 ticket, a $50 ticket and a $150 ticket. The 8 cents cancels at every ticket size.
Helcim's band step at $50,000 a month makes this worse still for Stax. Just below $50,000 the two sit within about a dollar of each other at the $199 floor. Just above it Helcim drops to 0.35% + 7 cents and pulls away again. The next crossover is about $60,300 a month at a $50 ticket. It's $70,200 at a $15 ticket and $58,000 at a $150 ticket, all at the $199 floor.
Online the answer changes, because the cent charges differ. Stax charges 15 cents. Helcim's entry online band charges 25 cents plus 0.50%. Stax's 10-cent advantage per transaction is real. At a small ticket there are enough transactions to pay for the subscription.
| Online, ticket | Where Stax overtakes Helcim | Tier | Rankable? |
|---|---|---|---|
| $25 | about $11,000/month | $99 | Yes |
| $25, second window | about $15,400/month | $139 | Yes |
| $50 | about $19,900/month | $139 | Yes, barely |
| $100 | about $33,200/month | $199 floor | No |
| $200 | about $36,200/month | $199 floor | No |
The $25 row has two entries because the answer sawtooths. Stax leads from about $11,000 to $12,500 a month. Then the subscription steps to $139 and Helcim retakes the lead until about $15,400. Then Stax leads again until $20,833 a month, where the price stops being published. That's not a rounding artefact. It's what a subscription tier does to a cost curve. It's also the best argument for running your own numbers instead of trusting a threshold.
Stax is the cheapest option this site can rank in exactly one situation. Online, small ticket, roughly $11,000 to $20,800 a month. There's a gap in the middle where the subscription steps to $139 and Helcim briefly retakes the lead. Everywhere else this site can rank, Helcim is cheaper or Stax's price isn't published.
Worked Examples
All three at rankable volumes, all with the interchange assumption stated at the top of the page. Interchange is a real line on the Stax and Helcim side. It's bundled inside the flat rate on the others. So it has to be in the model.
$5,000/Month Online, $25 Average Ticket (200 transactions)
That's $60,000 a year, so the $99 tier. Pass-through is $109.40 for everybody. 1.50% of $5,000 is $75.00. Add $0.172 x 200, which is $34.40.
| Total | Effective | |
|---|---|---|
| Helcim, entry band | $184.40 | 3.69% |
| Braintree | $202.50 | 4.05% |
| Square Free | $225.00 | 4.50% |
| Stax ($99 tier) | $238.40 | 4.77% |
| PayPal standard card | $247.50 | 4.95% |
Stax is fourth of five here. Below the flat-rate breakeven the subscription is a real cost with nothing to offset it. A $25 ticket makes it worse. $99 spread over 200 transactions is 50 cents a sale.
$20,000/Month Online, $25 Average Ticket (800 transactions)
That's $240,000 a year, so the $139 tier. Pass-through is $437.60.
| Total | Effective | |
|---|---|---|
| Stax ($139 tier) | $696.60 | 3.48% |
| Helcim, entry band | $737.60 | 3.69% |
| Braintree | $810.00 | 4.05% |
| Square Free | $900.00 | 4.50% |
| PayPal standard card | $990.00 | 4.95% |
Stax wins by $41 a month against Helcim, and by $113 against Braintree. This is the cell Stax is built for. Enough transactions for the 10-cent online advantage to matter, and a subscription that's still published.
Move the ticket to $50 and the margin nearly vanishes. Stax lands at $199.00 of markup against Helcim's $200.00. One dollar. Move it to $100 and Helcim wins outright.
$20,000/Month Card-Present, $50 Average Ticket (400 transactions)
That's $240,000 a year, so the $139 tier. Pass-through is $277.20.
| Total | Effective | |
|---|---|---|
| Helcim, entry band | $389.20 | 1.95% |
| Stax ($139 tier) | $448.20 | 2.24% |
| PayPal Zettle | $494.00 | 2.47% |
| Square Free | $580.00 | 2.90% |
Stax beats both flat rates by $46 and $132. It still loses to Helcim by $59. That's the shape of the card-present answer at every volume this site can rank. Stax's problem here isn't that it's expensive. It's that Helcim charges the same 8 cents with no subscription. Stax starts $139 behind with no percentage advantage to claw it back.
Interchange is an assumption in all three tables. It's also the largest single line in the Stax and Helcim columns. Replace it with your own blended rate from your last statement before you decide anything. A debit-heavy book is cheaper across the board. A premium-card book is dearer. Neither changes the ranking, because interchange is identical on both interchange-plus rows.
Stax vs Helcim: The Comparison That Decides It
Both pass interchange through. Both are transparent. This is the comparison most merchants should run. For most of them it comes out in Helcim's favour.
| Stax | Helcim | |
|---|---|---|
| Monthly fee | $99 to $199+, by annual volume | $0 |
| Percentage markup | 0% | 0.40% down to 0.15% card-present, 0.50% down to 0.15% online, by monthly volume band |
| Card-present per transaction | $0.08 | $0.08 down to $0.06 |
| Online per transaction | $0.15 | $0.25 down to $0.15 |
| Chargeback you win | Not published. $25 protection add-on available | $0 |
| Slow month | You still pay the subscription | You pay nothing |
| Price published above your volume? | Only to $250,000 a year | Yes, to $5 million a month |
Both verified 2 August 2026 from staxpayments.com/pricing and helcim.com/pricing.
Where Helcim wins:
- Card-present, at every volume where Stax publishes a price. The 8 cents is identical and Helcim adds no subscription.
- Online at a $100 or $200 ticket, at every rankable volume.
- Online at a $50 ticket below about $19,900 a month.
- Any month where your volume drops. Helcim charges nothing in a dead month.
- Any business with real dispute volume. Helcim publishes $0 for a chargeback you win. Stax publishes no base fee at all.
Where Stax wins:
- Online at a small ticket, roughly $25, between about $11,000 and $12,500 a month. And again between about $15,400 and $20,800 a month.
- Online at a $50 ticket, between about $19,900 and $20,800 a month.
- Possibly above $250,000 a year in several more places, on the "$199+" floor. Nobody can check that without a written quote.
Pick Stax when you're online with a small ticket. Your volume is steady, it sits in that window, and you've got the subscription price in writing. Pick Helcim when you're card-present. Or your ticket is large. Or your volume moves. Or you'd rather not have a monthly bill at all.
What Stax Does Well
1. Zero Percentage Markup
There isn't a percentage. That's genuinely unusual, and it's the whole product. Take $20,000 a month online at a $25 ticket, on the $139 tier. Stax's entire markup is $139 plus $120 in per-transaction fees. That's $259, or 1.30% of volume. Helcim's markup in the same cell is $300.
The catch: the model only pays once the subscription spreads over enough transactions. And above $250,000 a year, Stax stops publishing what the subscription is. The zero percentage is real. The price you pay for it isn't always public.
2. Predictable Monthly Cost
Your subscription is fixed. Your per-transaction fee is fixed. Only interchange varies. Budgeting is easier than with any percentage-based model. That's a real operational benefit, and it never shows up in a rate table.
3. Built-in Business Tools
The subscription includes invoicing with payment links, a virtual terminal for phone orders, a customer vault for repeat billing, and a reporting dashboard. Other processors charge separately for some of these. If you'd otherwise buy an invoicing tool, price that saving into the comparison. It can be worth more than the $59 a month separating Stax from Helcim in the card-present example above.
4. Human Support
Phone support during business hours and US-based staff, against the email-first model at Stripe and Square.
What Stax Does Poorly
1. The 8 Cents Card-Present Is Not an Advantage
Helcim's entry band charges the same 8 cents card-present. It adds no subscription. That one fact is why Stax can't win a card-present comparison at any volume where its price is published. Retail or restaurant, this is the finding that matters.
2. You Pay in Slow Months
The subscription doesn't pause. A seasonal business with four dead months pays $400 to $800 for nothing. Helcim's $0 monthly fee exists precisely for this case.
3. Dispute Pricing Is Not Published
Stax publishes a $25 chargeback protection add-on. It doesn't publish what a chargeback costs without it. Close that gap with a written answer before you sign. Especially if you're in a dispute-prone category.
4. "$199+" Starts at a Volume Ordinary SMBs Reach
The top published tier is "$199+ for $250,000 a year and above." That's $20,833 a month. It covers a $300,000-a-year business and a $30-million-a-year business alike. Stax doesn't say what the plus becomes. Every processor on this site is unrankable somewhere. Stax goes unrankable at a volume a successful small shop passes in its second year.
5. Limited Developer Tools and a Smaller Ecosystem
Stax's API isn't in Stripe's league. There are fewer e-commerce plugins and third-party integrations than Stripe or Square offer. Custom integration takes more effort.
Who Stax Is Best For
Good Fit
| Business Type | The condition attached |
|---|---|
| Low-ticket e-commerce | Roughly a $25 average order at $11,000 to $20,800 a month. This is the one cell where Stax is the cheapest option this site can rank |
| Professional services and B2B invoicing | High-ticket invoices, low transaction count. A flat 15 cents on a $2,000 invoice is nothing. Price Helcim too: at large tickets its 0.50% online markup is what you're comparing against, not its cents |
| Merchants who want invoicing and a virtual terminal bundled | Worth real money if you'd otherwise buy those separately. Put a number on it |
| Businesses that value a fixed, predictable bill | Legitimate reason to pay a little more. Just know that you might be |
Poor Fit
| Business Type | Better Alternative |
|---|---|
| Card-present retail, any volume | Helcim. Same 8 cents, no subscription |
| Under the flat-rate breakeven | Square or PayPal Zettle. No monthly fee |
| Seasonal | Helcim. No monthly fee, same transparency |
| Dispute-heavy | Helcim. $0 when you win, and it's published |
| Above $250,000 a year without a written quote | Anything with a published price, until Stax gives you a number |
| Retail needing a full POS | Square or Clover |
Common Gotchas
1. Annual Bands, Not Monthly
Said three times on this page. It's the error that made Stax look twelve times more expensive than it is. Take your annual volume into the tier table, not your monthly volume.
2. Correcting That Error Does Not Make Stax Cheapest
This is the second half of the same gotcha. Fixing the annual-versus-monthly mistake moves Stax from "far too expensive" to "worth pricing." It doesn't move it to "cheapest." Helcim charges no subscription and matches Stax's card-present cents exactly.
3. Contract Length
Stax's contract terms aren't published. Ask directly. "Can I cancel any time with no early termination fee?" Get the answer in writing.
4. Interchange Is Still Your Biggest Line
Stax adds no percentage, so interchange is essentially your whole percentage cost. Your card mix matters more here than with a flat rate. A flat rate absorbs the variance. Stax passes it straight through. A premium-rewards-heavy book costs more than a debit-heavy one, and Stax can't cushion that. See how this site models card mix, then check yours.
5. The Chargeback Add-On Is Not Insurance
$25 per chargeback for protection is a price, not a guarantee. Ask which liability transfers. Ask which reason codes are covered. Ask what the exclusions are. Then decide whether it counts as coverage.
Test to Run
Stax savings calculation, before switching:
- Get your current processor statement. Record total volume, total transaction count, total fees.
- Calculate your current effective rate:
total fees / total volume. - Find your tier using annual volume. Multiply monthly volume by 12, then look it up. If the answer is "$199+", stop. Get the real number in writing before going further.
- Estimate Stax:
subscription + (transactions x $0.15 online or $0.08 card-present) + (volume x your blended interchange). - Don't know your blended interchange? Use the assumption on this site: 1.50% + $0.172 online or 1.03% + $0.178 card-present, both including assumed network assessments. Mark the answer as an estimate and see where those numbers come from.
- Run Helcim with the same inputs. This is the comparison that decides it, not the flat-rate one. Card-present, expect Helcim to win. Online at a small ticket in the $11,000 to $20,800 range, expect it to be close.
- Add your dispute costs. Stax doesn't publish a base fee, so get one before you finish the model.
- Compare. Is Stax at least $50 a month cheaper after everything, including against Helcim?
Success criteria. Stax saves you $600 a year or more against Helcim, not against a flat rate. Your volume is steady enough that you'll still be above the breakeven in your worst month. And your subscription price is a number, not a number with a plus sign.
Next Steps
Considering Stax?
- Run the calculation above with your own numbers, using annual volume for the tier.
- Confirm your subscription price in writing, especially if you're anywhere near $250,000 a year.
- Ask what a chargeback costs on the base plan.
- Compare with Helcim before you compare with anything flat-rate. That's the comparison Stax has to win.
Already on Stax?
- Check you're on the right tier for your annual volume. Merchants get moved up and rarely get moved back down.
- If you're card-present, price Helcim. The 8 cents is identical and there's no subscription to earn back.
- Review your card mix. Stax adds no percentage, so interchange is your whole percentage cost.
- Compare your effective rate to benchmarks.
See Also
- Helcim - The processor Stax has to beat, with no monthly fee and $0 chargebacks when you win
- How We Compare Processor Costs - The interchange assumption behind every crossover on this page
- Square - Flat-rate alternative with a full POS
- PayPal - Zettle is the lowest published flat card-present rate here
- Processor Comparison - Full comparison table
- Understanding Fees - How interchange works
- Interchange Reference - Interchange rate tables