Assumable Mortgage Calculator
Compare assuming an existing low-rate mortgage vs getting a new loan at today's rates.
Existing Loan to Assume
New Loan Comparison
Assumed vs New Loan — Monthly Payment Comparison
Assumes $400K original loan, 28 years remaining, vs new 30-year loan at current rates
| Original Rate | Assumed Payment | New at 6.875% | Monthly Savings | 30-Year Savings |
|---|---|---|---|---|
| 2.50% | $1,422 | $2,499 | $1,077 | $361,908 |
| 3.00% | $1,510 | $2,499 | $989 | $332,308 |
| 3.25% | $1,555 | $2,499 | $944 | $317,508 |
| 3.50% | $1,601 | $2,499 | $898 | $302,108 |
| 4.00% | $1,695 | $2,499 | $804 | $270,108 |
| 4.50% | $1,793 | $2,499 | $706 | $237,408 |
How We Calculate This
This assumable mortgage calculator uses established formulas and industry-standard data to provide accurate estimates.
- Enter your specific values into the calculator fields above
- Our algorithm applies the relevant formulas using your inputs
- Results are calculated instantly in your browser — nothing is sent to a server
- Review the detailed breakdown to understand how each factor affects your result
These calculations are estimates based on standard formulas. For critical decisions, always consult a qualified professional.
How to Convert Oven Recipes to Air Fryer
This calculator compares the cost of assuming an existing mortgage at its original low interest rate versus originating a new mortgage at current market rates. Assumable mortgages (FHA, VA, and USDA loans) let a buyer take over the seller's existing loan terms.
The basic rule:
- Remaining balance is calculated by amortizing the original loan and finding the balance at the current point in time
- Assumed loan payment uses the original rate for the remaining term — same payment the seller was making
- Required down payment for assumption = purchase price − remaining loan balance
- New loan payment is calculated at current market rates for the full new term with your chosen down payment
Assumable mortgages have become extremely valuable in the 2025-2026 rate environment, where many sellers hold 2.5-4% rates while current rates are near 7%. Only government-backed loans (FHA, VA, USDA) are assumable — conventional loans generally are not. The assumption process requires lender approval and can take 45-90 days.
When Would You Use This Calculator?
This assumable mortgage calculator is designed for anyone who needs quick, reliable estimates without complex spreadsheets or professional consultations.
- When you need a quick estimate before committing to a purchase or project
- When comparing different options or scenarios side by side
- When planning a budget and need to understand potential costs
- When you want to verify a quote or estimate you've received from a professional
- When teaching or learning about the concepts behind these calculations
Frequently Asked Questions
What is an assumable mortgage?
An assumable mortgage lets a home buyer take over the seller's existing loan — same balance, same interest rate, same remaining term. FHA, VA, and USDA loans are assumable by design. This is extremely valuable when the seller has a rate far below current market rates, such as a 3% loan in a 7% rate environment.
How much can I save by assuming a mortgage in 2026?
Savings depend on the rate difference. On a $400,000 balance, assuming a 3.25% rate instead of getting a new 6.875% loan saves roughly $900/month and over $150,000 in total interest. With 2020-2022 era rates around 2.5-4% and current rates near 7%, the savings potential is massive.
What is the catch with assumable mortgages?
The biggest challenge is the down payment. You must pay the difference between the purchase price and the remaining loan balance in cash (or with a second mortgage). If a home is worth $500K but the remaining balance is $320K, you need $180K upfront. Second mortgages or assumption-bridge loans can help.
Can I assume a conventional mortgage?
Almost never. Conventional mortgages typically have a due-on-sale clause that prevents assumption. Only government-backed loans — FHA, VA, and USDA — are reliably assumable. Some older conventional loans (pre-1988) and some ARMs may be assumable, but these are rare.
How long does a mortgage assumption take?
The assumption process typically takes 45-90 days, though some lenders take longer. The buyer must qualify with the existing lender, pass credit checks, and meet debt-to-income requirements. Unlike a new loan, you cannot shop for a different lender — you must work with the seller's existing servicer.
Do I need to pay closing costs on an assumed mortgage?
Closing costs for assumptions are typically much lower — usually $1,000-$5,000 versus $8,000-$15,000 for a new loan. There's no origination fee, no appraisal requirement in some cases, and fewer third-party fees. VA assumptions may require a funding fee (0.5% of balance).