Mortgage Recast Calculator
You have a lump sum and a mortgage. There are three different things you can do with it, and they give completely different results. This prices all three side by side - including the point where a refinance finally pays back its own fees.
Recasting would make your payment
-
- Your payment now
- $0
- Monthly saving
- $0
- Balance after the lump
- $0
- Cash you need upfront
- $0
- Best on total interest
- -
Where the money goes
The green block is monthly saving and it stays yours. The orange is your payment now and it does not come back.
Move it and watch
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at {v} for what you still owe
And what you can change
Why your own figure may differ
All your choices, side by side
The same lump sum, four different outcomes. Look at the last two columns together - the option with the lowest payment is rarely the one that saves the most interest.
| Choice | Monthly payment | Paid off in | Total interest | Interest saved |
|---|
Recasting a mortgage: real examples
Three ways the same lump sum plays out. Click any card to load it.
- Wants breathing room
$50,000 against a $300,000 balance
6% rate with 30 years left, and a $250 recast fee.
Recasting drops the payment from about $1,799 to $1,499 - $300 a month back in your pocket, with the same end date.
Load this scenario in the calculator → - Wants to be done sooner
The same $50,000, payment unchanged
Keep paying $1,799 a month after the lump.
The mortgage clears 10 years 2 months earlier and saves $169,329 in interest - far more than recasting. Same money, very different result.
Load this scenario in the calculator → - Weighing a refinance
Offered 5% with $6,000 in costs
Currently on 6% with 30 years left.
The lower rate helps, but you have to earn back the $6,000 first. The break-even tells you how many months that takes.
Load this scenario in the calculator →
Common questions about recasting a mortgage
What is a mortgage recast?
You pay a lump sum off what you owe, and the lender works out a new, smaller monthly payment spread over the same left time. Your interest rate does not change and your final payoff date does not change - only the size of each payment. Lenders usually charge a small fee for doing it.
How is that different from just paying extra?
Both start the same way - a lump off the balance. The difference is what happens next. A recast lowers your monthly payment and keeps the same end date. Paying extra keeps your payment the same and brings the end date forward instead. Same money in, two completely different outcomes. This calculator prices both so you can see which one you actually want.
Recast or refinance?
A recast keeps your existing rate and costs a small fee. A refinance replaces the loan entirely, so it only makes sense if you can get a meaningfully better rate - and you have to earn back the closing costs first. If rates have gone up since you borrowed, a recast is usually the better tool. This calculator shows both, with the break-even point on the refinance.
What does the break-even mean?
A refinance costs money upfront. The break-even is how many months of lower payments it takes to earn those costs back. If you might move or refinance again before then, you would lose money on the deal. It is the single most useful number when comparing a refinance to anything else.
Will my lender let me recast?
Most will on ordinary conventional loans, though there is usually a minimum lump sum and a fee. Government-backed loans often cannot be recast at all. It is worth one phone call before you plan around it - ask for the minimum, the fee, and whether your loan type qualifies.
Which choice is best?
It depends on what you want. Want more breathing room in your monthly budget? Recast. Want to be free of the mortgage sooner and pay the least interest overall? Keep paying the same amount. Can you get a much better rate and will stay long enough to earn back the fees? Refinance. The calculator marks whichever saves the most interest, but the cheapest option is not always the right one for your life.