How to Use
Enter the home purchase price or loan amount after subtracting your down payment.
Input the annual interest rate from your lender quote or use current average 30-year fixed rates as a benchmark.
The term is fixed at 30 years (360 months); confirm this matches your loan structure.
Instantly view your estimated monthly principal-and-interest payment in real time.
Review the total interest paid figure - this is the full additional cost of the loan beyond the home price.
Compare this result against the 15-year mortgage calculator to see the monthly payment vs. lifetime interest trade-off.
What Is This Tool?
A 30-year fixed-rate mortgage is the most widely used home loan in the United States. It spreads repayment across 360 monthly payments at a locked interest rate, offering the lowest possible monthly payment for a given loan amount. The primary advantage is cash flow flexibility - a lower required payment leaves more room in your monthly budget for savings, investments, and emergencies. The trade-off is total cost: because interest accrues on a larger remaining balance for a longer time, the total interest paid over 30 years is dramatically higher than on a shorter-term loan. On a $300,000 mortgage at 6.5%, the interest alone over 30 years totals roughly $382,000 - more than the original purchase price.
Why It Matters
The 30-year mortgage's lower monthly payment is a major financial lever - it can be the difference between qualifying for a home and not, or between a tight budget and a healthy savings rate. But the long timeline has a hidden cost: because you pay interest on a larger balance for longer, the total interest bill is enormous. Many borrowers also move or refinance before the 30-year term ends - meaning they pay primarily interest during the early years of their loan, when each payment is largely interest rather than principal reduction.
Worked example: 30-year vs. 15-year on the same loan
On a $300,000 loan at 6.5%, the 30-year payment is about $1,896 in principal and interest, with roughly $382,600 of interest over the full term. A 15-year loan on the same amount, typically at a slightly lower rate near 6.0%, runs about $2,532 a month but only around $155,700 in total interest. The 15-year costs roughly $636 more each month and saves about $227,000 in interest. The common mistake is treating this as a permanent either-or: you can take the 30-year loan for its lower required payment, then voluntarily pay close to the 15-year amount most months. That captures most of the interest savings while leaving you the smaller payment as a fallback when money is tight.