How to Pick the Right Processor
NerdWallet's payment processor comparison shows Stripe at 2.9% plus $0.30 and Square at 2.9% plus $0.30 charging identical rates for online transactions, and we see sellers agonize over this choice when the real difference is in developer tools and checkout customization where Stripe has a clear edge -- but for in-person sales Square drops to 2.6% plus $0.10 per tap, which is about half a percentage point cheaper than Stripe's 2.7% plus $0.05 terminal rate. We track both in our calculator because that gap adds up to roughly $50 in monthly savings at $10,000 in volume just from picking the right processor for the right channel, and marketplace platforms are a different calculation entirely since Etsy, eBay, and Mercari charging 10% to 13% includes delivering the customers to your listing, which means paying 13% on a sale you never would have made without their traffic is still a better deal than paying 3% on zero sales from a standalone store nobody visits.
Baymard Institute research puts the average online cart abandonment rate at 70.19% with roughly 10% of those abandonments caused by insufficient payment methods, and we see that checkout friction compound with hidden processing costs to create a double hit on revenue that most sellers never fully account for -- international cards add 1% to 1.5% on top of your base rate, currency conversion stacks another 1% to 3%, chargebacks cost $15 to $25 each regardless of outcome, and even winning a dispute does not refund the fee on most platforms. We built the effective rate calculator into our tool specifically because dividing total monthly fees by total revenue is the only honest view of what processing actually costs, and a seller with an advertised rate of 2.9% who discovers their effective rate is actually 3.5% after international transactions and premium card surcharges now understands exactly where that margin went.
PayCompass data shows Square holding roughly 54% of the US small business payment market thanks to the lowest card-present rates and a free hardware ecosystem, and after comparing all twelve platforms in our database we see a clear pattern -- Stripe and Square are nearly interchangeable for online payments, PayPal costs more at 3.49% plus $0.49 but carries buyer trust and international reach that neither competitor can match, and Early Warning Services reported via PR Newswire that Zelle hit over $1 trillion in transfer volume during 2024 because free instant transfers through banking apps serve a fundamentally different need than commercial processing. We track every platform in our comparison tool because NerdWallet's processor guide confirms what we see in the data: the honest recommendation is to match your processor to your primary sales channel rather than hunting for the single lowest rate, since saving 0.3% on processing means nothing if your checkout flow drives away customers or your platform lacks the buyer trust that closes the sale. For a broader view of business math, our discount calculator handles percentage-off pricing and our pay raise calculator shows salary increases across every pay period.