What Is a Loan Payment Calculator?
A loan payment calculator estimates the fixed monthly payment you'll make on an amortizing loan — such as a mortgage, auto loan, or personal loan. It uses the loan amount (principal), the annual interest rate, and the loan term to compute a level payment that fully pays off the balance by the end of the term. The tool also breaks down how much you pay in total and how much of that is interest.
How to Use It
Enter the loan amount you plan to borrow, the annual interest rate as a percentage, and the loan term in years. The calculator converts the annual rate into a monthly rate, computes the number of monthly payments, and returns your fixed monthly payment along with the total paid over the life of the loan and the total interest.
The Formula Explained
The payment is found with the standard amortization formula:
$$M = P \cdot \frac{r}{1 - (1 + r)^{-n}}$$
Here \(P\) is the principal, \(r\) is the monthly interest rate (annual rate \(\div 12 \div 100\)), and \(n\) is the total number of payments (years \(\times 12\)). If the interest rate is 0%, the payment is simply the principal divided by the number of payments.
Worked Example
Suppose you borrow $200,000 at 6% annual interest over 30 years. The monthly rate is \(0.06 / 12 = 0.005\) and \(n = 360\). The payment is $$200000 \times \frac{0.005}{1 - 1.005^{-360}} \approx \$1{,}199.10$$ per month. Over 360 payments you'd pay about $431,676 total, of which roughly $231,676 is interest.
FAQ
Does this include taxes and insurance? No. It calculates principal and interest only. Escrow items like property tax or insurance are separate.
Can I use it for any loan? Yes — it works for mortgages, car loans, student loans, and personal loans that use standard monthly amortization.
Why does total interest seem so high? Longer terms and higher rates dramatically increase total interest because you carry the balance longer. Try a shorter term to compare.
