No extra payment
Lifetime interest
$0
Payoff
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🇺🇸 United States · Property
Mortgage Calculator
Estimate your monthly mortgage and housing costs, explore lifetime interest, and see how extra principal payments could change your payoff date.
Monthly payment breakdown
Amortization schedule
Extra-payment analysis
Runs in your browser
Extra-payment impact
What could an extra payment change?
Compare your standard mortgage schedule with the same mortgage plus your selected monthly extra principal.
With extra principal
Lifetime interest
$0
Payoff
—
Extra-payment effect
Interest saved
$0
Time saved
0 months
Amortization
See how your mortgage balance changes
The calculator computes every monthly payment. For easier reading, the table shows the first 12 payments followed by annual snapshots and the final payment.
| Payment | Date | Total payment | Principal | Interest | Balance |
|---|
How this mortgage calculator works
The calculator uses the standard fixed-rate mortgage amortization formula to estimate the monthly principal and interest payment. Each payment is then divided between interest and principal as the remaining loan balance declines.
Property taxes, homeowners insurance, HOA fees and estimated private mortgage insurance are added separately to give a broader estimate of monthly housing costs.
Monthly housing cost is not the same as your
contractual mortgage payment.
Property taxes, insurance, HOA fees and PMI can change
independently of your principal-and-interest payment.
Mortgage payment formula
For a fixed-rate mortgage, the scheduled monthly principal-and-interest payment is based on the original loan amount, monthly interest rate and total number of monthly payments.
M = P × [ r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) ]
M = monthly principal and interest payment
P = principal borrowed
r = monthly interest rate
n = total number of monthly payments
Why extra mortgage payments can matter
Interest is calculated from the outstanding mortgage balance. When an additional payment is applied directly to principal, the balance used for later interest calculations becomes smaller.
As a result, consistent extra principal payments can reduce both the time required to repay a mortgage and the total interest paid over the life of the loan.
Confirm with your mortgage servicer that additional
payments will be applied to principal and check whether
your loan has any prepayment restrictions or penalties.
What is included in the estimate?
Principal and interest
This is the scheduled payment required to amortize the mortgage balance over the selected loan term at the assumed fixed interest rate.
Property taxes
Property taxes vary by state, county, municipality and property. This calculator lets you enter an estimated annual property-tax percentage rather than pretending there is one national US rate.
Homeowners insurance
Enter your estimated annual homeowners insurance premium. Actual premiums vary based on location, coverage, property characteristics, insurer and other factors.
Private mortgage insurance
The calculator provides an editable PMI assumption when the down payment is below 20%. Actual mortgage-insurance requirements and pricing depend on the loan program, lender, insurer, loan-to-value ratio, credit profile and other factors.
HOA fees
If the property belongs to a homeowners association, enter the estimated monthly HOA charge separately.
Frequently asked questions
Does a 20% down payment always eliminate mortgage insurance?
Not necessarily. Mortgage-insurance rules depend on the loan type and lender. The calculator uses the 20% threshold only as a practical conventional-mortgage modeling assumption.
Does the calculator include closing costs?
No. Closing costs are separate from the recurring monthly housing costs modeled here. They can include lender fees, appraisal costs, title charges, prepaid taxes and insurance, and other transaction expenses.
Does the calculator use today's mortgage rates?
No. The interest rate is an assumption you control. This avoids presenting a generic market rate as though it were a personalized lender quote.
Why can my actual monthly payment change?
Even with a fixed-rate mortgage, property taxes, insurance premiums, HOA fees and mortgage insurance can change. If those amounts are paid through escrow, your total amount paid to the servicer can therefore change.
Are extra payments guaranteed to save the amount shown?
No. The estimate assumes the extra amount is consistently applied to principal according to the schedule shown. Actual servicing practices and payment timing can affect results.
Methodology & limitations
This calculator models a fully amortizing fixed-rate mortgage with monthly payments. It does not model adjustable-rate mortgages, interest-only periods, balloon payments, temporary rate buydowns or other specialized mortgage structures.
Property tax, insurance, HOA and PMI values are user assumptions. They do not affect the mortgage amortization itself unless specifically represented as additional principal.
Last reviewed: October 4, 2026
Estimates are for educational and planning purposes only.
They are not a mortgage offer, lending decision, appraisal
or professional financial advice.