Mortgage Interest Calculator
Estimate how much interest you will pay over the life of your loan. Compare terms and see how extra payments create massive savings.
Loan Details
Any extra amount paid toward principal each month.
The True Cost of Borrowing
Base Monthly Payment: $1,896
Total Interest Paid
Total Loan Cost (Principal + Interest)
Total Savings
Year 1 Reality Check
In your first 12 months, you will pay $22,754 to the lender. However, $19,401 of that goes straight to interest, and only $3,353 actually pays down your home's principal.
See the Real Cost of Borrowing
Mortgage interest is the cost you pay for borrowing money to buy a home.
A mortgage interest calculator helps you estimate monthly interest, total interest over the loan term, and how different rates, loan amounts, and extra payments can change your long-term cost.
Interest Cost
Your interest cost depends on the loan amount, interest rate, and repayment term.
Even a small rate difference can change your monthly payment and total interest paid over time.
Monthly Breakdown
Each mortgage payment usually includes principal and interest.
Early in the loan, more of the payment often goes toward interest.
As the balance gets smaller, more of each payment goes toward principal. The calculator's "Year 1 Reality Check" visualizes this breakdown.
Rate Impact & Term
Interest rate changes can make a big difference.
A 30-year mortgage may have a lower monthly payment than a 15-year loan, but it can cost more in total interest.
Use the toggle at the top of the calculator to instantly see the difference in total interest paid when you drop from a 30-year to a 15-year term.
Key Inputs to Test:
- Loan amount
- Interest rate
- 15 vs 30 year term
- Extra payments
Extra Payments
Extra payments can significantly reduce interest if they go toward principal.
Lower principal means less balance for future interest to build on. Even small extra payments may create meaningful savings over time.
- Test adding an extra $100/month
- Watch the total interest drop
- See how many years you shave off
Interest Planning Note
A mortgage interest calculator helps you see what borrowing truly costs.
By comparing rates, terms, extra payments, and total interest, you can choose a mortgage strategy that fits both your monthly budget and long-term savings goals.
Smart Check
Before choosing a loan, review:
- Interest rate
- APR
- Loan term
- Monthly payment
- Total interest
- Prepayment rules
Quick Answers
How does a 15-year mortgage compare to a 30-year mortgage?
A 15-year mortgage has a higher monthly payment than a 30-year mortgage, but it cuts the total interest paid significantly—often by more than half. You build equity much faster, but you must be able to afford the larger monthly obligation.
Why is so much of my early payment going toward interest?
Mortgages use an amortization schedule. In the early years, interest is calculated on the massive starting principal balance, so most of your payment goes to the lender. As the balance shrinks over the years, a larger portion of your payment begins paying down the principal.
How do extra payments reduce my total interest?
Any extra payment made specifically toward your 'Principal' reduces your loan balance immediately. Because future interest is calculated on that smaller balance, you save money on interest every single month for the rest of the loan, ultimately paying off the house years early.
What is the difference between Interest Rate and APR?
The interest rate is the cost of borrowing the principal amount. The APR (Annual Percentage Rate) includes the interest rate PLUS lender fees, closing costs, and insurance, giving you a broader picture of the true yearly cost of the loan.