Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Better option (lower payment for less upfront cost)
Refinance
New payment after recast
$1,753
New payment after refinance
$1,749
Monthly savings from recast
$250
Monthly savings from refinance
$255
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How to use this
- 1Enter current mortgage balance ($).
- 2Enter current interest rate (%).
- 3Enter remaining term (years).
- 4Enter lump sum available ($).
- 5Enter recast fee ($).
- 6Enter available refinance rate (%).
- 7Enter refinance closing costs ($).
- 8Read your better option (lower payment for less upfront cost) on the right — it updates as you type.
- 9Hit Share to keep the scenario or send it to someone.
About this calculator
A recast keeps your existing rate and term but re-amortizes the payment after you make a large lump-sum principal payment, usually for a $150–$500 flat fee and no credit check or appraisal — it lowers your payment without touching your rate. A refinance replaces the loan entirely, which can lower your rate but comes with full closing costs (2–5% of the loan) and resets underwriting. This calculator compares the new monthly payment and total costs of each option given the same lump sum available, so you can see whether it's worth paying refinance closing costs to chase a lower rate versus simply recasting at your current rate for a fraction of the cost.
Worked example
Using the values the calculator loads with:
Inputs
- Current mortgage balance: 320000 $
- Current interest rate: 5.5 %
- Remaining term: 24 years
- Lump sum available: 40000 $
- Recast fee: 300 $
- Available refinance rate: 5.25 %
- Refinance closing costs: 6000 $
Results
- Better option (lower payment for less upfront cost): Refinance
- New payment after recast: $1,753
- New payment after refinance: $1,749
- Monthly savings from recast: $250
- Monthly savings from refinance: $255
What each field means
Inputs
- Current mortgage balance ($)
- The current mortgage balance used in the calculation, measured in $. Starts at 320000 $ so you have a working example on load.
- Current interest rate (%)
- The current interest rate used in the calculation, measured in %. Starts at 5.5 % so you have a working example on load. Accepted range: 0–12 %.
- Remaining term (years)
- The remaining term used in the calculation, measured in years. Starts at 24 years so you have a working example on load. Accepted range: 1–30 years.
- Lump sum available ($)
- The lump sum available used in the calculation, measured in $. Starts at 40000 $ so you have a working example on load.
- Recast fee ($)
- The recast fee used in the calculation, measured in $. Starts at 300 $ so you have a working example on load.
- Available refinance rate (%)
- The available refinance rate used in the calculation, measured in %. Starts at 5.25 % so you have a working example on load. Accepted range: 0–12 %.
- Refinance closing costs ($)
- The refinance closing costs used in the calculation, measured in $. Starts at 6000 $ so you have a working example on load.
Results
- Better option (lower payment for less upfront cost)
- Returned as a plain value and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- New payment after recast
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- New payment after refinance
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Monthly savings from recast
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Monthly savings from refinance
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What can't a recast do that a refinance can?
A recast never changes your interest rate or loan term — it only lowers the payment by re-amortizing the same rate over the same remaining schedule after a lump-sum paydown. If your goal is to actually get a lower rate, shorten your term, switch loan type, or pull cash out, only a refinance accomplishes that.
Do all lenders and loan types allow recasting?
No. Conventional loans held by many servicers allow recasting, but FHA, VA, and USDA loans typically do not. Always confirm with your specific servicer, since recast policies (minimum lump sum required, fee, processing time) vary by lender even among those that allow it.
Does a recast affect my credit score or require an appraisal?
No — recasting requires no credit pull, no appraisal, and no new underwriting since it's the same loan. That's the core appeal: a low-cost, low-friction way to lower your payment if you come into extra cash, versus refinancing's full loan-origination process.
When does refinancing clearly win despite the higher cost?
When the new rate is meaningfully lower (generally 0.75%+ below your current rate) or you want to change loan terms — shorten from 30 to 15 years, drop PMI, or switch from ARM to fixed. The rate difference has to be large enough to outrun the thousands in closing costs within a reasonable time horizon.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
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HELOC Draw Period Cost Calculator
See what an interest-only draw period actually costs before repayment kicks in.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Mortgage Recast vs. Refinance Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/mortgage-recast-vs-refinance
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/mortgage-recast-vs-refinance" target="_blank" rel="noopener">Mortgage Recast vs. Refinance Calculator — RevenueLab</a> (2026).</p>
Source: [Mortgage Recast vs. Refinance Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/mortgage-recast-vs-refinance) (2026).