Assumable Mortgage
Calculator
Compare assuming a seller's 3% loan against today's rates, honestly
Models the full assumption structure: the assumed balance at the inherited rate, gap financing for the equity difference, and a straight comparison against a new loan at market rate, with a verdict that admits when assumption does not win.
See It In Action
Play with the calculator below. This is exactly what your visitors will see.
Assumable Mortgage Calculator
Compare assuming a seller's low-rate loan against a new mortgage at today's rates
Monthly Savings by Assuming
$305
Assumption Verdict
Assuming this loan saves money
5-year net savings: $17,385
The Assumption Structure
Assumed Loan Payment
$1,517
Gap Loan Payment
$738
Combined Payment
$2,255
New Loan Payment
$2,560
Financing Detail
Equity Gap to Finance
$85,000
Assumption Fee
$900
5-Year Net Savings
$17,385
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How It Works
Get your results in four simple steps
Enter the scenario
Fill in 10 plain-English inputs across 3 short sections. Sensible defaults get you a result immediately.
Read the verdict
Results update instantly: the headline figure, supporting stats, and clear pass/fail states where qualification applies.
Share or download
Send a live share link or download a branded PDF scenario report to keep the conversation going.
Why This Calculator
Purpose-built features that give you the insights you actually need.
Seller's Loan (To Assume)
The existing loan you would take over
Your Financing
Down payment and the gap loan
Traditional Loan (For Comparison)
Today's market alternative
How the Assumable Mortgage math works
Compare assuming a seller's low-rate loan against a new mortgage at today's rates
Industry Standards We Follow
- Blended payment: assumed note + gap financing
- Comparison at the same down payment against a new market-rate loan
Key Variables in Our Calculation
- sellerMonthlyRateSeller's monthly rate
- sellerTermMonthsAssumed loan months remaining
- assumedPaymentMonthly P&I on the assumed balance at the inherited rate
- gapNeededEquity gap to finance beyond the down payment
- gapMonthlyRateGap loan monthly rate
- gapTermMonthsGap loan months
- gapPaymentMonthly payment on the gap loan
- combinedPaymentTotal monthly P&I with the assumption structure
Expert Insights
Get the most out of your calculations with these professional tips
Start from the defaults
Defaults reflect current market conditions; change only what you know about your scenario.
Stress-test the result
Nudge the most uncertain input both directions to see how sturdy the conclusion is.
Put it on your site
Embed this mortgage calculator with your branding and capture the leads it generates.
Frequently Asked Questions
Everything you need to know about the Assumable Mortgage Calculator
FHA, VA, and USDA loans are assumable with lender approval. Conventional loans generally are not. The buyer must qualify with the servicer, and on VA assumptions the seller should confirm entitlement release.
The equity gap. You must cover the difference between the price and the loan balance with cash or a second loan at today’s rates, which can erase the savings. The calculator prices exactly that tradeoff.
Who Uses This Calculator
Buyers
See whether an assumable listing actually saves you money once the gap loan is priced in.
Listing Agents
Market an assumable FHA/VA loan with real numbers instead of a vibe.
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