About EngPay.com

EngPay.com is a free, advertising-supported site built around six calculators for anyone who takes, studies, or is trying to understand payments, plus a set of written guides and a small museum of payment history. Rather than tell a founding story, this page just walks through what’s actually here and how each part works.

Fees and effective rate

Two tools deal with the question every merchant eventually asks: what did that transaction actually cost? The Payment Fee Calculator takes a percentage rate plus a fixed per-transaction fee and works out the total fee, what you net, your effective rate, and the running total across a batch of sales. The Effective Rate Calculator starts from the other direction — divide your total monthly processing fees by the volume you actually processed, and it surfaces the single blended rate hiding behind a pricing sheet, along with your true cost per transaction.

Chargebacks

A chargeback rarely costs just the disputed amount. The Chargeback Cost Calculator adds the dispute fee, the lost goods, and the processing fee you don’t get back, then projects what that comes to over a year at your chargeback rate and sales volume — a total that’s easy to underestimate until it’s added up in one place.

Currency conversion

For payments that cross a border, the Currency Conversion Calculator starts from the mid-market rate, applies an FX markup on top, and shows what you actually receive, exactly what the markup cost you, and your real effective rate once that markup is accounted for.

Subscription revenue

For recurring billing, the Subscription Revenue Calculator turns a subscriber count and a price into MRR and ARR, then projects twelve months forward adjusted for monthly churn and, optionally, growth — a quick way to sanity-check a subscription model before committing to it.

Comparing processors

Choosing between two processors is rarely just about the headline rate. The Processor Comparison Calculator takes the rate, fixed fee, and monthly fee for two providers, applies them to your volume and average ticket, and shows each one’s total cost, which is cheaper, and the annual difference between them.

The museum

Alongside the calculators sits the Museum of Money & Payments, with galleries on money through the ages, the rise of cards and cashless payment, digital money and mobile wallets, and the banks and institutions behind a transaction. Every entry, image, and fact in it is drawn from Wikipedia and Wikimedia Commons, not written by us.

What this is, and isn’t

EngPay.com is an independent site supported by advertising, which is how it stays free with no account or sign-up required. It isn’t affiliated with any card network, payment processor, or standards body it discusses, and it doesn’t hold or process anyone’s payment data — every calculator runs entirely on the numbers you type in, in your own browser. Results are estimates based on those numbers and on standard, published formulas, not financial, legal, investment, or compliance advice. Fees, rates, and provider terms change, so verify anything that matters against your own provider or a qualified professional before making a business decision. Longer guides live under Blog and Learn; for anything else, there’s a short Contact page.