50-Year Mortgage Calculator
Compare 30, 40 and 50-year terms on the same loan — monthly payment, lifetime interest, and how much of the balance you’d actually own along the way.
Longer loans carry more duration risk, so they price above the 30-year. Drag to zero for the same-rate comparison most articles use.
And costs $525,103 more in interest — $3,431 for every dollar off the monthly payment.
| Term | Rate | Monthly | Interest | Owned by yr 5 | To 80% LTV |
|---|---|---|---|---|---|
| 30 years | 6.660% | $2,571 | $525,383 | $24,874 | 12 yr 4 mo |
| 40 years | 7.035% | $2,496 | $798,032 | $10,813 | 20 yr 2 mo |
| 50 years | 7.035% | $2,417 | $1,050,485 | $5,193 | 28 yr 9 mo |
By year 5 you would own $5,193 of the $400,000 balance, against $24,874 on the 30-year.
Twenty extra years of payments buys a 6% discount on the monthly bill. The equity column is the one that decides whether you can sell, refinance or move without writing a cheque.
How to read the results
The monthly column is the part that sells a longer mortgage, and it’s the smallest number on the table. Stretching a $400,000 loan from 30 years to 50 at the same rate saves about $267 a month. Add the rate premium a 50-year loan would realistically carry and that drops to roughly $151. You’re adding twenty years of payments for a discount of a few percent on the true all-in cost of owning the house, since taxes and insurance don’t shrink at all.
The last two columns are where the decision actually lives. “Paid off by year 5” is the share of the loan you’d genuinely own after five years of on-time payments, and on a 50-year term it’s startlingly small — around $5,000 on a $400,000 loan. Everything else you might call equity would come from the house appreciating, which is not something you control.
Why the rate premium matters more than it looks
Set the premium slider to zero and the 50-year term looks tolerable. Move it to a third of a point and roughly 40% of the monthly saving disappears. That single assumption changes the answer more than the loan size does, which is why it’s an input here rather than a number we picked for you.
Nobody knows what a 50-year loan would actually price at, because none exist. But the 40-year terms used in loss-mitigation programs don’t trade at 30-year pricing, and a quarter to half a point is the sensible range to plan around.
The PMI trap
If you’re putting less than 20% down, look hard at the last column. PMI cancellation based on your original purchase price runs off the amortization schedule, so a slower schedule means years more of premiums. On a 30-year loan you’d reach the 80% threshold in about twelve years; on a 50-year, closer to twenty-nine. Unless the home appreciates enough that you can request cancellation on current value, a longer term can quietly cost you a decade of mortgage insurance on top of the extra interest.
For the background on where the proposal stands and what would have to change legally before any of this is real, see our guide to the 50-year mortgage.