15-Year vs 30-Year Mortgage Calculator

To calculate 15 year mortgage vs 30 year payments, compare both terms on the same principal balance. On a $320,000 loan balance: a 15-year mortgage at 5.80% requires $2,666/month with $159,860 total interest, while a 30-year mortgage at 6.50% requires $2,023/month with $408,142 total interest. The 15-year loan requires $643 more per month but saves $248,282 in total lifetime interest.

To calculate payments, use the monthly amortization equation M = P[r(1+r)^n]/[(1+r)^n - 1]. For a $320,000 loan balance: at 5.8% for 15 years (n=180), M = $2,666/month with $159,860 in total interest. At 6.5% for 30 years (n=360), M = $2,023/month with $408,142 in total interest. The 15-year mortgage requires $643 more per month but saves $248,282 in lifetime interest charges.

This calculator compares your monthly principal and interest payments, total loan costs, and cumulative interest paid over 15 years versus 30 years. For a $320,000 loan balance, the 15-year payment is approximately $2,666/month (at 5.8%) versus $2,023/month for a 30-year mortgage (at 6.5%)—an increase of $643 per month in exchange for saving $248,282 in lifetime interest.

A 15-year mortgage payment is typically 25% to 35% higher each month than a 30-year mortgage for the same loan balance. However, because principal is retired twice as fast and carries a lower interest rate, you eliminate over 60% of total lifetime interest charges.

Choosing a 15-year term over a 30-year term typically reduces your lifetime interest bill by 60% to 65%. On a $320,000 mortgage at 2026 rates, you save roughly $248,282 in interest and become mortgage-free 15 years sooner.

A 30-year mortgage provides financial safety: if your income drops or unexpected expenses arise, you are only committed to the lower monthly payment. You can voluntarily make extra principal payments to pay it off in 15 years with complete flexibility and without contractual risk.

At 2026 benchmark rates (5.8% for 15-yr, 6.5% for 30-yr): On $300k: $2,500/mo (15-yr) vs $1,896/mo (30-yr), saving $232,764 in interest. On $400k: $3,333/mo (15-yr) vs $2,528/mo (30-yr), saving $310,352 in interest. On $500k: $4,166/mo (15-yr) vs $3,160/mo (30-yr), saving $387,940 in interest.

Yes. Homeowners frequently start with a 30-year mortgage for cash flow flexibility and refinance into a 15-year fixed term once their household income increases or when interest rates drop.

To calculate the 15-year vs 30-year difference: Step 1: Determine loan principal (Home Price minus Down Payment). Step 2: Calculate monthly interest rate r = annual APR / 12. Step 3: Compute monthly P&I payment using M = P × [r(1+r)^n] / [(1+r)^n - 1] with n=180 for 15 years and n=360 for 30 years. Step 4: Multiply monthly payment by n to obtain total loan payout, then subtract principal to reveal lifetime interest savings. ConvertSheet automates these exact calculations in real time.

A 15 vs 30 year mortgage calculator evaluates the fixed monthly amortization formula M = P × [r(1+r)^n] / [(1+r)^n - 1] across two term horizons: n = 180 months (15 years) and n = 360 months (30 years). At current benchmark rates (e.g. 6.71% for 15-year vs 7.40% for 30-year under Freddie Mac PMMS), the 15-year term accelerates principal reduction, delivering over 60% total interest savings despite a higher monthly payment.