How to use this calculator
Estimate monthly payments and total interest. Enter loan amount ($), annual rate (%), term (months). The result updates when you change an input. To compare two sets of inputs, save scenario A, then enter the second set; the result panel shows the difference.
Formula and limits
Monthly rate r = annual rate ÷ 1200. Payment = P × r ÷ [1 − (1+r)^−n], or P ÷ n at zero interest. Fixed rate, monthly payments, no fees. This assumes the stated annual rate is the interest rate, not a fee-inclusive APR.
Worked example
The following example uses the calculator’s starting values. It is an illustration of the method, not a recommended target.
| Input | Example value |
|---|---|
| Loan amount ($) | 15000 |
| Annual rate (%) | 7 |
| Term (months) | 60 |
Monthly principal + interest: $297.02
Total interest: $2,821.08
Interpreting your result
The result is the monthly principal and interest payment for a fixed rate and term. The entered annual rate is used as an interest rate, not a fee-inclusive APR. Compare total interest as well as the monthly payment when changing the term; taxes, fees, and insurance are outside this estimate.
Comparing alternatives
Save the first result as scenario A, then change one input. The comparison shows the numeric difference; it does not label either result as better. Choose inputs that describe realistic alternatives. Values shown on screen are rounded, so calculations from rounded intermediate results may differ slightly.
Background reading
Investor.gov financial tools. This is a subject reference, not an endorsement or independent review of Calcaven.