Do nothing
—
monthly payment
Remaining interest
—
Mortgage Recast Calculator
A lower payment, or an earlier payoff? Compare what happens when you put a lump sum toward your mortgage.
Free · Private · No sign-up
Your recast estimateMonthly · USD
New monthly payment
$2,026
Principal and interest. Same rate, same remaining term.
Monthly reduction
$338
$4,051 per year
Lump sum only
—
payment unchanged
Paid off earlier by
—
Lump sum + recast
—
new required payment
Interest difference
—
| Scenario | Monthly payment | Remaining interest | Payoff |
|---|---|---|---|
| Do nothing | — | — | — |
| Lump sum only | — | — | — |
| Lump sum + recast | — | — | — |
Balance after lump sum
—Fee break-even
—Recast fee
—What this mortgage recast estimate means
A recast keeps the same interest rate and remaining payoff timeline but recalculates the required principal-and-interest payment after a lump-sum principal reduction. Keeping your old payment after the lump sum generally pays the loan off sooner; recasting generally creates more monthly cash-flow room.
How the calculator works
Finly uses the standard fixed-rate amortization formula. The “do nothing” scenario amortizes your current balance, “lump sum only” reduces principal while keeping the payment unchanged, and “lump sum + recast” amortizes the lower balance across the original remaining months.
Formula
M = P × r ÷ (1 − (1 + r)−n), where P is principal, r is the monthly interest rate, and n is remaining monthly payments. A 0% rate uses principal divided by months.
Worked mortgage recast example
Start with a $350,000 balance at 6.5% with 25 years remaining, then apply a $50,000 principal payment and a $250 recast fee. The calculator shows the recalculated required payment beside the unchanged-payment payoff strategy, including remaining interest and fee break-even.
Assumptions and limitations
- Fixed interest rate, monthly payments, and monthly compounding.
- Payments shown exclude taxes, insurance, HOA dues, and mortgage insurance.
- The lump sum is applied directly to principal before the recast.
- Lender eligibility, minimum payments, timing rules, and fees vary. Confirm them with your servicer.
Sources
Calculation logic follows standard loan amortization described by the Consumer Financial Protection Bureau. Lender-specific recast rules are not inferred.
Frequently asked questions
How much does a mortgage recast lower the monthly payment?
The reduction depends on the principal paid down, interest rate, and months remaining. Finly recalculates payment from the lower balance while keeping the existing rate and remaining term.
Does a mortgage recast change the interest rate?
No. A recast keeps the existing rate and recalculates the required payment from the lower principal balance and remaining term.
Is recasting the same as making a lump-sum payment?
No. A lump-sum payment reduces principal. A recast is the lender process that recalculates the required payment afterward.
Does a mortgage recast shorten the loan term?
A standard recast keeps the original remaining payoff timeline and lowers the required payment. Continuing to pay more than the new minimum can still accelerate payoff.
Can every mortgage be recast?
No. Eligibility, minimum principal reductions, timing, and fees vary by lender and loan type. Many government-backed loans are not eligible, so confirm the current rules with the loan servicer.
Related calculators
Reviewed September 17, 2026. Calculation logic was tested independently. This tool is educational and is not financial, tax, or legal advice.