Money calculators · Updated September 3, 2026
Mortgage Recast Calculator
Put a lump sum toward your mortgage and see the lower payment a recast gives you, versus keeping your payment and finishing early.
| Interest saved by recasting (after fee) | $51,027 |
| If you prepay and keep the old payment: paid off in | 18 years 8 months |
| Interest remaining if you prepay instead | $208,975 |
| Extra interest of recasting vs prepaying | $98,936 |
How a recast is calculated
new balance = balance − lump sum new payment = new balance × r ÷ (1 − (1 + r)^−months remaining), r = rate ÷ 12 interest saved = (old payment − new payment) × months remaining − lump sum − fee
The prepay comparison keeps your current payment on the reduced balance and simulates month by month until the loan is gone. Escrow amounts are not part of the payment shown.
Frequently asked questions
What is a mortgage recast?
A recast (re-amortization) applies a lump sum to your principal and then recalculates the monthly payment over the remaining term at the same rate. Your rate and payoff date stay the same; the payment drops. Lenders usually charge a small fee and require a minimum lump sum, often $5,000 to $10,000.
Recast or prepay: which saves more interest?
Prepaying the same lump sum and keeping the old payment pays the loan off earlier and saves more interest; recasting lowers the payment but keeps the original term. The results show both: at the defaults, keeping the old payment finishes in 18 years 8 months.
Does a recast change my interest rate?
No. That is the main difference from refinancing: a recast keeps your existing rate and loan, with no new closing costs or credit check, which makes it attractive when current rates are higher than yours.
Can any mortgage be recast?
Most conventional loans can; FHA, VA and USDA loans generally cannot, and some jumbo lenders do not offer it. Ask your servicer for its recast policy, minimum amount and fee.
Is a recast worth the fee?
Compare the fee (typically $150 to $500) with the monthly savings. At the defaults the payment falls by $324.61 a month, so the fee is recovered in the first months.
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Sources and updates
Figures are for tax year 2026 and were checked against the sources below on . Rates change every January; we review every data file at the start of each year and whenever a state announces a mid-year change.
This calculator gives estimates for information only and is not tax, legal or financial advice. Your employer's payroll system, local taxes, benefits and year-to-date wages can change the exact amounts on your pay stub. See how we calculate.