Personal Finance
Mortgage Calculator
The biggest debt of your life deserves a second look. See the monthly payment, total interest, and true cost of the loan.
A mortgage payment is calculated with the amortization formula: P = L × r(1+r)^n ÷ ((1+r)^n − 1), where L is the loan, r the monthly interest rate, and n the number of payments. Early payments are mostly interest.
Payment = amortization formula.
Early years are mostly interest.
Total interest often rivals the loan itself.
Calculate Your Mortgage/Loan
Monthly Payment
What Is Mortgage/Loan?
A mortgage is an amortizing loan: fixed payments that gradually shift from interest-heavy to principal-heavy over the term.
The calculator shows the payment, total interest, and true total cost, the numbers lenders advertise least and buyers need most.
How It Is Calculated
P = L × r(1+r)^n ÷ ((1+r)^n − 1), r = rate/12, n = years×12
Example: Example: $300,000 at 6.5% for 30 years → $1,896/month; total interest ≈ $382,600
The same $300k at 6.5%, term matters
| Term | Payment | Total interest |
|---|---|---|
| 30 years | $1,896 | $382,600 |
| 20 years | $2,237 | $236,900 |
| 15 years | $2,613 | $170,400 |
Limitations
- Doesn't include taxes, insurance, PMI, or HOA, add those to the payment for a real budget.
- Adjustable-rate loans change the math over time.
- Prepayment and refinancing materially change total interest.
Sources & Review
References used for this calculator’s formulas and thresholds:
Mortgage/Loan FAQ
How is a mortgage payment calculated?
With the amortization formula, a fixed payment that covers the month's interest plus a slice of principal, recalculated each month.
Why is most of my first payment interest?
Interest accrues on the whole balance. Early on, the balance is huge, so interest dominates; as principal falls, the mix flips.
15-year or 30-year mortgage?
15-year: higher payment, far less total interest. 30-year: flexibility. If cash flow allows, the 15-year often wins mathematically.
Does paying extra help?
Dramatically, extra payments hit principal directly, skipping future interest. One extra payment a year cuts ~4 years off a 30-year loan.
Please read this first: these results are educational estimates. For real decisions, talk to a qualified professional.