Refinance 30 Year to 15 Year Calculator
Switching from a 30-year mortgage to a 15-year term raises the monthly payment significantly but slashes total interest, often by more than half. The shorter term also typically qualifies for a lower rate, amplifying savings. Enter your current loan details and the proposed 15-year terms in the calculator above to see both the payment increase and the lifetime interest difference.
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- Payment after
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- Saved each month
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- Closing costs
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- Interest over the full life
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A positive lifetime figure means the new loan costs more in total interest even though the monthly payment fell — usually because the term restarted. Both numbers matter.
The Payment Jump and Interest Savings
On a $300,000 balance at an illustrative rate, the monthly principal-and-interest payment on a 30-year term might be approximately $1,800. Refinancing the same balance into a 15-year term — even at a modestly lower rate — could push the payment to approximately $2,300. That is roughly $500 more per month, a figure that demands careful budget scrutiny.
The payoff comes in total interest. Over 30 years the borrower might pay approximately $348,000 in interest on that $300,000 loan. Over 15 years, even with slightly larger payments, total interest drops to approximately $114,000. The difference — more than $230,000 — represents money that stays in the borrower's pocket rather than flowing to the lender.
Shorter terms also build equity faster. By year five of a 15-year loan, a much larger share of each payment has gone to principal compared with the same point on a 30-year schedule. That accelerated equity growth can matter if you plan to sell, borrow against the home, or simply want financial flexibility sooner.
Is the Higher Payment Sustainable?
The biggest risk is cash-flow strain. A $500 monthly increase must be sustainable not just today but through job changes, medical expenses, and economic slowdowns. If the higher payment pushes your front-end DTI past 28 percent — or the back-end past 36 percent under conventional guidelines — lenders may not approve the refinance at all.
Opportunity cost is the second consideration. The extra $500 per month directed to the mortgage cannot go to retirement accounts, taxable investments, or an emergency fund. For borrowers with limited liquidity, a side-by-side 15 vs 30 comparison that includes investment return assumptions gives a fuller picture.
A middle path is refinancing into a 20-year or 25-year term, which splits the difference between payment size and interest savings. Or keep the 30-year term but make voluntary extra payments equivalent to the 15-year schedule — this preserves flexibility because the extra portion is optional each month. The extra-payment amortization calculator models exactly that scenario.
Payment and interest figures depend on the rates and balance you enter. Actual lender terms may include closing costs that shift the total comparison.