Mortgage Recast Calculator

Background.

A reader arrives at Mortgage Recast Calculator to estimate the lower payment after a principal curtailment is re-amortized over the existing remaining term. A recast changes scheduled payment without changing note rate or maturity, unlike a refinance. For that reason, this page names its convention as “recast payment amortizes the balance remaining after a lump-sum principal curtailment over the existing rate and remaining term.”

The editable entries are current principal balance before recast payment, lump-sum principal curtailment, existing note annual interest rate, remaining amortization term, current scheduled monthly principal and interest. Use values from the document or measurement that governs this mortgage recast question; the defaults are only the worked fixture below. Before relying on the number, check this mortgage recast boundary: servicer eligibility, minimum curtailment, fees, escrow and mortgage-insurance treatment are not included.

Fannie Mae Selling Guide B3-3.1-08, Rental Income; documented gross and net rental-income treatment documents the convention or governing rule used here. The mortgage recast output is a transparent scenario under those facts: it does not manufacture an unentered market price, professional determination, carrier quote, legal eligibility finding or locally adopted code value.

What is mortgage recast calculator?

Mortgage Recast is the relationship behind this decision: a recast changes scheduled payment without changing note rate or maturity, unlike a refinance. On this page it means recast payment amortizes the balance remaining after a lump-sum principal curtailment over the existing rate and remaining term. Servicer eligibility, minimum curtailment, fees, escrow and mortgage-insurance treatment are not included; that is the line between the reported quantity and a broader real estate analysis.

How to use this calculator.

1. 01Confirm that “recast payment amortizes the balance remaining after a lump-sum principal curtailment over the existing rate and remaining term” matches the mortgage recast convention you need.
2. 02Replace the fixture values for current principal balance before recast payment, lump-sum principal curtailment, existing note annual interest rate, remaining amortization term, current scheduled monthly principal and interest with dated values from the governing record.
3. 03Keep all currencies, measurement units and time periods on the same basis before calculating.
4. 04Read recast monthly principal and interest together with this boundary: Servicer eligibility, minimum curtailment, fees, escrow and mortgage-insurance treatment are not included.

The formula.

The calculation uses recast payment amortizes the balance remaining after a lump-sum principal curtailment over the existing rate and remaining term. In this mortgage recast model, the entered terms are current principal balance before recast payment, lump-sum principal curtailment, existing note annual interest rate, remaining amortization term, current scheduled monthly principal and interest. A recast changes scheduled payment without changing note rate or maturity, unlike a refinance, which is why the relationship is presented under this name rather than as a universal alternative. Servicer eligibility, minimum curtailment, fees, escrow and mortgage-insurance treatment are not included. Calculations keep full decimal precision through the relationship and round only the returned display values.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Fannie Mae Selling Guide B3-3.1-08, Rental Income; documented gross and net rental-income treatment. Retrieved 2026-08-07. access: open unless marked otherwise.
2. [2]Freddie Mac, Modeling Multifamily Potential Rental Income; current rent roll, concessions and vacancy treatment. Retrieved 2026-08-07. access: open unless marked otherwise.
3. [3]U.S. Consumer Financial Protection Bureau. What is an amortization schedule?. Retrieved 2026-08-07. independence: primary; access: open.
4. [4]U.S. Consumer Financial Protection Bureau. Loan estimate explainer. Retrieved 2026-08-07. independence: primary; access: open.
5. [5]Fannie Mae. Single family selling guide. Retrieved 2026-08-07. independence: primary; access: open.