How your monthly payment is calculated
Every fixed-rate loan payment covers two things: a portion that pays down the principal, and a portion that pays interest to the lender. Early on, interest makes up the bigger share; as the balance shrinks, more of each payment chips away at what you actually borrowed.
The amortization formula
Monthly payment equals principal multiplied by the monthly interest rate, multiplied by (1 + rate) to the power of the number of payments, all divided by ((1 + rate) to that same power, minus 1). It looks dense, but it's just the standard formula lenders use to keep every payment the same size over the life of the loan.
Ways to lower your payment
- Put down a larger down payment to shrink the principal you're borrowing against.
- Shop around — even half a percentage point in rate changes your total cost meaningfully.
- Extend the term to lower the monthly payment, understanding it raises total interest paid.
- Improve your credit before applying, since it directly affects the rate you're offered.
Frequently asked questions
What's the difference between a fixed and variable rate?
A fixed rate stays the same for the life of the loan, so your payment never changes. A variable rate moves with the market, which means your payment can rise or fall over time.
Does this include taxes and insurance?
No. This calculator estimates principal and interest only. Property taxes, homeowners insurance, and HOA fees are billed separately and would add to your total monthly cost.
How does the loan term affect total interest?
A shorter term raises your monthly payment but sharply cuts total interest, since you owe the balance for less time. A longer term lowers the monthly payment but costs more in interest overall.