Mortgage Calculator
Enter a loan amount, annual interest rate and term in years, and this mortgage calculator returns the fixed monthly payment, the total you will repay and how much of that is interest. It uses the standard amortizing loan formula with monthly compounding.
How to use it
Type the amount you plan to borrow (the price minus your down payment), the yearly interest rate as a percentage, and the term in years. Press Calculate payment. Change one value at a time to see how rate and term affect the monthly cost and the total interest.
How it is calculated
The monthly payment for a fixed-rate loan is M = P x i x (1 + i)^n / ((1 + i)^n - 1), where P is the loan amount, i is the monthly rate (annual rate divided by 12 and by 100) and n is the number of monthly payments (years x 12). If the rate is 0, the payment is simply P / n.
Total repaid is M x n, and total interest is that figure minus P. The result covers principal and interest only. Property tax, insurance, fees and any rate changes are not included, so real payments may be higher.
Examples
A 300,000 loan at 6% for 30 years: i = 0.005, n = 360, (1.005)^360 is about 6.0226. M = 300,000 x 0.005 x 6.0226 / 5.0226 = 1,798.65 per month. Total repaid is about 647,515, so interest is about 347,515.
The same loan over 15 years (n = 180) costs about 2,531.57 per month, but total interest drops to roughly 155,683.
FAQ
Does this include taxes and insurance?
No. It calculates principal and interest only. Add your local property tax, insurance and any fees separately to estimate the full monthly cost.
Why is so much of my early payment interest?
Interest is charged on the remaining balance, which is highest at the start. Each payment is the same, so early payments are mostly interest and later ones mostly principal.
What if my loan has a variable rate?
The tool assumes one fixed rate for the whole term. For a variable rate, run it again with the new rate and the remaining balance and term.
How do extra payments change the result?
Paying extra reduces the balance sooner, which cuts the interest and shortens the term. This calculator shows the standard schedule without extra payments.
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