$1,769.79
$357,124.57
$637,124.57
$1,516.67
$253.12
$0.00
$1,769.79
$357,124.57
$637,124.57
$1,516.67
$253.12
$0.00
The Mortgage Amortization Calculator shows you exactly how each monthly payment is divided between principal and interest over the life of your loan. Amortization is the process of gradually paying off a debt through regular installments that cover both the interest and a portion of the principal balance.
Understanding amortization is crucial because it reveals a surprising truth about mortgage payments: in the early years, the majority of your payment goes toward interest, not principal. On a typical 30-year mortgage at 6.5%, approximately 70% of your first payment is interest. This ratio gradually shifts over time until, in the final years, nearly all of each payment goes toward principal reduction.
This calculator also demonstrates the powerful impact of extra principal payments. Even modest additional payments — such as $100 or $200 per month — can shave years off your mortgage term and save tens of thousands of dollars in interest. The earlier you start making extra payments, the more you save because you reduce the principal balance on which future interest is calculated.
The amortization schedule is a standardized financial tool used by every mortgage lender, bank, and credit union in the United States. By examining this schedule, borrowers can make informed decisions about whether to refinance, how much extra to pay each month, and when they will reach key equity milestones like the 20% equity threshold needed to eliminate PMI.
Lenders are required by the Truth in Lending Act (TILA) to disclose the total cost of a loan, including total interest charges. This calculator helps you verify those disclosures and compare different loan scenarios side by side.
Each monthly payment is calculated using the standard amortization formula:
M = P × [r(1 + r)n] / [(1 + r)n − 1]
For each payment period, the interest portion = remaining balance × monthly rate, and the principal portion = total payment − interest portion. The remaining balance decreases by the principal portion each month, so subsequent payments have less interest and more principal.
With extra payments, the additional amount goes entirely toward principal, reducing the balance faster and shortening the loan term. Interest saved = total interest without extra payments − total interest with extra payments.
The first month's interest and principal split shows how your payment is allocated at the start. Over time, the interest portion decreases while the principal portion increases. Extra payments accelerate this process dramatically. The interest saved figure shows the lifetime benefit of consistent extra payments.
Inputs
Results
At 6.5%, you pay $357,142 in total interest — more than the original loan amount.
Inputs
Results
Adding $200/month extra saves approximately $82,456 in interest and pays off the loan ~6 years early.
Amortization is the process of paying off a loan through regular scheduled payments of principal and interest. Each payment is the same amount but the split between principal and interest changes over time.
Interest is calculated on the remaining balance. When the balance is highest (at the start), the interest charge is highest. As you pay down principal, less interest accrues each month.
On a $280,000 loan at 6.5%, you'll pay approximately $357,142 in interest — about 127% of the original loan. A 15-year loan at the same rate would cost roughly $142,000 in interest.
Yes. An extra $200/month on a $280,000 loan at 6.5% saves about $82,000 in interest and pays off the loan 6+ years early. The earlier you start, the more you save.
If your mortgage rate is lower than expected investment returns (after tax), investing may be better financially. However, paying off a mortgage provides guaranteed savings and peace of mind. Consider your risk tolerance.
On a 30-year mortgage at 6.5%, this crossover point occurs around year 18-20. On a 15-year mortgage, it happens much sooner, typically around year 6-8.
Some lenders offer mortgage recasting: after a large lump-sum payment, they recalculate your monthly payment based on the new lower balance while keeping the same interest rate and remaining term.
Refinancing creates a new amortization schedule starting from scratch. If you refinance into a new 30-year loan, you restart the front-loaded interest cycle unless you choose a shorter term.
Most modern mortgages do not have prepayment penalties. However, some loans — particularly subprime or certain adjustable-rate mortgages — may include them. Check your loan documents.
Biweekly payments (every two weeks) result in 26 half-payments per year, equivalent to 13 monthly payments instead of 12. This effectively makes one extra payment per year, significantly reducing total interest.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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