50-Year Mortgage Calculator

What Is a 50-Year Mortgage?

A 50-year mortgage is an ultra-long-term home loan that stretches repayment over half a century. It represents the longest widely discussed mortgage term and offers the lowest possible fixed monthly payment — but at the cost of dramatically higher total interest. These loans are rare, niche products that exist primarily for specific high-cost market scenarios.

How Does a 50-Year Mortgage Work?

A 50-year mortgage amortizes the loan balance over 600 monthly payments (50 years x 12 months). The mechanics are the same as any fixed-rate mortgage, but the extremely long term creates notable effects:

• Monthly payments are minimally lower than a 40-year mortgage (diminishing returns)
• Nearly all early payments go to interest — principal reduction is extremely slow
• Total interest can exceed the original loan amount on larger loans
• Interest rates are significantly higher than standard 30-year rates

30-Year vs. 40-Year vs. 50-Year Comparison

The table reveals a critical pattern: going from 30 to 40 years saves $67/month but costs $271K more in interest. Going from 40 to 50 years saves only an additional $41/month but costs another $270K in interest. The diminishing returns are severe.

Who Might Consider a 50-Year Mortgage?

A 50-year mortgage is a niche product for very specific situations:

• Ultra-high-cost markets (e.g., San Francisco, New York) where even 40-year payments are a stretch
• Real estate investors who prioritize cash flow above all else and plan to sell or refinance within 5-10 years
• Borrowers with irregular income (seasonal workers, commission-based earners) who need the smallest required payment
• Jumbo loan borrowers purchasing luxury properties where the absolute payment amount is very large

The Math: Why 50 Years Barely Helps Monthly Payments

The reason a 50-year term doesn’t lower payments much more than a 40-year term is mathematical: as the loan term increases, the impact on monthly payments shrinks because most of the early payment is already going to interest.

For a $500,000 loan:

Saving $135/month sounds appealing — until you realize the 50-year loan costs an additional $676,972 in total interest compared to the 30-year loan.

Risks and Drawbacks

Financial risks:

• Total interest may exceed the original loan amount
• Equity builds so slowly you could be underwater for years if home values dip
• You’ll pay mortgage insurance (PMI) for much longer if your down payment is under 20%

Practical risks:

• Very few lenders offer 50-year terms
• Most are non-QM loans with fewer consumer protections
• Many are adjustable-rate, adding uncertainty to future payments
• Resale or refinance may be complicated with minimal equity

Alternatives to a 50-Year Mortgage

Before committing to a 50-year term, consider these alternatives:

1. 40-year mortgage — Nearly as low a payment with significantly less total interest
2. Interest-only period — Many 30-year mortgages offer a 5-10 year interest-only option with similar initial payments
3. Adjustable-rate mortgage (ARM) — A 5/1 or 7/1 ARM may offer lower initial rates than a 50-year fixed
4. Buying less home — A lower purchase price with a 30-year term may achieve the same monthly payment
5. FHA loan with lower down payment — Lower entry costs with standard term lengths

Example: $600,000 Luxury Home Purchase

For a $600,000 home with 20% down ($120,000 down, $480,000 loan):

The 50-year mortgage saves $130/month compared to the 30-year option, but costs an additional $649,893 in total interest — nearly $650,000 for the privilege of lower monthly payments.