Does assuming that 3% loan actually pencil?
Taking over a seller's low-rate FHA or VA mortgage sounds like a cheat code — until you hit the equity gap. Enter the numbers and see the blended rate, the monthly payment, and whether it truly beats a normal purchase.
The loan & the deal
$165,000 equity gap
$75,000 financed by a 2nd
Why the equity gap decides everything
The seller's 3% rate isn't on the whole house — it's only on their remaining loan balance. The rest (the “equity gap”) you cover in cash or with a second mortgage at today's rate, and that market-rate second is what usually erases the savings. Assumptions pencil in just three situations: a small gap, a cash buyer who skips the second, or a VA-to-VA assumption. This tool tells you which one you're in.
Want the full worked examples, the VA-entitlement trap for sellers, and the truth about subject-to? Read: I ran the numbers on assumable mortgages in Pinellas.
Frequently asked questions
How does an assumable mortgage calculator work?
It compares two ways to buy the same home: assuming the seller’s existing low-rate FHA/VA loan (and covering the equity gap with cash or a second mortgage) versus taking a normal loan at today’s rate. It shows the equity gap, the blended rate on the financed amount, the monthly payment each way, and whether the assumption actually saves money.
What is the "equity gap" in an assumption?
The difference between the sale price and the seller’s remaining loan balance. The buyer must cover it in cash or with a second mortgage at today’s rate. When that gap is large, the market-rate second wipes out the savings from the low first-loan rate — which is why most assumptions don’t pencil.
When does assuming a mortgage actually save money?
Three cases: the equity gap is small (the seller has little equity), the buyer can cover the gap in cash instead of a market-rate second, or it’s a VA-to-VA assumption. The calculator shows which case you’re in — if the "assumption path" monthly is below the normal-purchase monthly, it pencils.
Have a specific loan in mind?
Send me the address or your current loan and I'll pull the real assumption math — balance, gap, blended rate, and whether it beats a normal purchase. Free, 15 minutes.
Get the real numbers →Estimates only — P&I, not taxes/insurance. Assumption approval, second-mortgage terms, VA entitlement, and due-on-sale enforcement depend on your specific loan and servicer. Confirm with a licensed lender before acting; this is general information, not lending advice.