Computing Interest Rates Programs

In the old days, companies would issue their buy rate for the term and amount for sales representatives’ calculations. They then add the factor to 1.00 and multiply it times the company buy rate. For instance, .0331 and the salesman wanted five points, multiply 1.05 times .0331 and it would be .034755. Then multiply this to the amount being financed to get the monthly payment.

Today, the most popular calculator software is TValue, available online or software for your computer of smartphone:
https://www.timevalue.com/tvalue-products

You can also purchase the calculator to put on your website by going to: https://www.timevalue.com/tcalc-financial-calculators

There are other financial portals and calculation tools:
Bankrate.com
Kiplinger.com
The Motley Fool

Merchant Cash Advance APR Calculator
  Kabbage, OnDeck, plus Term Loan APR Calculator
    (upper left on site below, plus add below site to your website)
https://www.nav.com/business-loan-calculators/merchant-cash-advance-apr-calculator/