Calculate your monthly loan payment for any loan type — mortgage, auto, personal, or student loan. See total interest paid and how the loan balance decreases over time.
Monthly Payment
$2k
Total Interest
$319k
Total Paid
$569k
With an amortized loan, each payment covers both interest and principal. Early payments are mostly interest; later payments are mostly principal. On a 30-year mortgage, roughly 80% of your first payment goes to interest. By the end, nearly 100% goes to principal. Understanding this helps you see why extra payments early in the loan save the most.
On a $300,000 30-year mortgage, the difference between 5% and 7% interest is $400/month ($1,610 vs. $2,000) and $145,000 in total interest over the life of the loan. Even a 0.25% rate reduction can save tens of thousands of dollars. Shopping around for rates and improving your credit score before borrowing pays off significantly.
A 15-year mortgage vs. 30-year mortgage has higher monthly payments but dramatically less total interest. On a $300,000 loan at 6%, the 30-year option costs $348,000 in interest; the 15-year option costs $156,000. That's a $192,000 difference. Even making one extra payment per year on a 30-year mortgage cuts about 5 years off the term.
M = P × [r(1+r)n] ÷ [(1+r)n − 1]
This calculator uses the standard amortization formula where M is the monthly payment, P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is total number of payments (years × 12). It also calculates total interest paid and shows how the remaining balance decreases over the loan term.
A $300,000 mortgage at 6.5% for 30 years: monthly payment is $1,896. Over the full term, you'd pay $382,633 in total — $300,000 in principal and $82,633 in interest. Switching to a 15-year term at the same rate raises the payment to $2,613/month but reduces total interest to $170,388, saving $212,245.
Compare 15-year vs. 30-year terms by adjusting the years slider. The monthly payment increases, but the total interest savings are often six figures.
To see the impact of refinancing, enter your current remaining balance and the new rate. Compare the new monthly payment and total cost against your current loan.
Even small rate differences matter enormously over long loan terms. A 0.5% lower rate on a $300,000 mortgage saves roughly $30,000-$40,000 over 30 years.
If you're shopping for a mortgage, use this calculator to determine the maximum loan amount that keeps your payment within 28% of your gross monthly income.