Mortgages
Mortgage Recast Calculator
A recast is the quiet alternative to refinancing. You put a lump sum against principal, the lender re-amortises what's left over the same remaining term, and your monthly payment falls — no new loan, no credit check, usually a fee of a few hundred dollars.
Tested against worked examplesHow we verify
New monthly payment: $1,688.02
New monthly payment
$1,688.02
Same payoff date, smaller payment.
- Monthly saving
- $337.60
- Payment today
- $2,025.62
- Balance after the lump sum
- $250,000
- Interest saved
- $51,280
Compare scenariosTry three values of one input
| Current balance | |||
|---|---|---|---|
| New monthly payment | $1,485.46 | $1,688.02+$202.56 | $1,890.58+$405.12 |
| Payment today | $1,823.06 | $2,025.62+$202.56 | $2,228.18+$405.12 |
| Balance after the lump sum | $220,000 | $250,000+$30,000 | $280,000+$60,000 |
Every other input stays at the value you set above — currently $300,000 for current balance. Differences are measured against the first column.
Saved scenariosSave this calculation
Saved in this browser only — no account, and nothing is sent to us. Clearing your browser data deletes them.
How this calculator works
The current payment is the level payment that amortises today's balance over the remaining term at your rate. The new payment does the same for the balance after the lump sum, over the identical term. Interest saved compares total payments minus principal in each case.
Principal and interest only — taxes, insurance, and any PMI are unchanged by a recast and are not shown. Servicer fees are excluded; subtract them from the interest saved for the true net benefit.
What this assumes
- A recast re-amortises the existing loan over its remaining term after a lump-sum principal payment. The rate and the payoff date do not change.
- Your servicer permits recasting and charges the fee you enter — not all loans allow it, and government-backed loans generally do not.
- The lump sum is cash you already have; the opportunity cost of using it is not modelled.
What changes this number
- Size of the lump sum
- Drives the payment reduction proportionally, since the same term is recalculated on a smaller balance.
- Remaining term
- A recast late in a loan spreads the reduction over few payments, so the monthly effect is small.
- Recast versus prepay
- Prepaying without a recast keeps the payment and shortens the loan; recasting lowers the payment and keeps the date. They are opposite goals.
A worked example
Take the $50k on a $300k balance scenario. These figures are produced by the calculator above, not written alongside it, so they always match what the tool returns.
What you enter
- Current balance
- $300,000
- Remaining term
- 300 months
- Lump sum toward principal
- $50,000
What it returns
- New monthly payment
- $1,688.02
- Monthly saving
- $337.60
- Payment today
- $2,025.62
- Balance after the lump sum
- $250,000
- Interest saved
- $51,280
Try an example
Frequently asked questions
What is a mortgage recast?
You pay a lump sum against principal and ask the servicer to re-amortise the loan over the remaining term. The rate and payoff date do not change; the payment drops because the same schedule now covers a smaller balance. Fees are typically a few hundred dollars, against thousands for a refinance.
Recast or just pay extra?
They spend the same money on different outcomes. Extra payments keep your payment the same and pull the payoff date closer, saving the most interest. A recast keeps the date and lowers the payment, improving monthly cash flow. Choose breathing room or a shorter loan — the lump sum cannot buy both.
Recast or refinance?
Recast if your rate is already good: it is cheap, quick, and requires no underwriting. Refinance if rates have fallen far enough to justify closing costs, since only a refinance changes the rate. Someone holding a 3% mortgage in a 7% market almost never wants to refinance — recasting keeps that rate intact.
Will my lender allow it?
Most conventional loans permit it; FHA, VA, and USDA loans generally do not. Servicers usually require a minimum lump sum (often $5,000–$10,000), a current payment history, and charge a processing fee. Ask specifically for a 'recast' or 're-amortisation' — front-line staff sometimes confuse it with refinancing.
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Disclaimer: DayCents provides this calculator for educational purposes only. Results are estimates based on your inputs and the stated assumptions — they are not financial advice, a quote, or an offer of credit. Consult a qualified financial professional before making major money decisions.