40-Year Mortgage Calculator.
The extreme-affordability mortgage. Stretches payments to 40 years for the lowest possible monthly. Used in high-cost markets, by FHA modification programs, and in some Asian markets. Not a typical choice.
A $500,000 loan at 7% over 40 years = monthly payment of $3,107, total interest $991,435. Adjust amount and rate in the calculator below.
Mortgage Calculator
Is the 40-year right for you?
✅ Pros
- →Lowest possible monthly payment
- →Helps qualify in expensive markets
- →Available for FHA loan modifications
- →Maximum cash flow for other priorities
⚠️ Cons
- →Highest total interest of any common term
- →Available only from select lenders (or modification only)
- →Higher interest rate (typically 50-75 bps above 30-year)
- →Equity builds at a glacial pace
- →Mortgage outlives your working career
Ideal borrower profile
- ✓ Borrowers in extremely high-cost markets (California, Hawaii, NYC)
- ✓ FHA loan-modification participants
- ✓ Asian markets where 35-50 year terms exist
- ✓ Buyers facing financial hardship who need lower payment
How the 40-year compares.
Same $500,000 loan, different terms. Each at the typical rate for that term.
| Term | Rate | Monthly | Total Interest | Total Paid |
|---|---|---|---|---|
| 10 yr | 5.75% | $5,488 | $158,615 | $658,615 |
| 15 yr | 6% | $4,219 | $259,471 | $759,471 |
| 20 yr | 6.25% | $3,655 | $377,114 | $877,114 |
| 25 yr | 6.4% | $3,345 | $503,458 | $1,003,458 |
| 30 yr | 6.5% | $3,160 | $637,722 | $1,137,722 |
| 40 yr ← | 7% | $3,107 | $991,435 | $1,491,435 |
Highlighted row = current page. Rates shown are typical for prime borrowers in May 2026.
The math nobody shows you.
A $500,000 loan at 7.0% over 40 years = $3,107/month and $991,469 total interest. The same loan at 6.5% over 30 years = $3,160/month and $637,723 total interest. The 40-year saves only $53/month — but costs $353,746 more in total interest. Only worth it for hardship or qualification edge-cases.