Mortgage Calculator

Estimate fixed-rate principal and interest, entered housing costs, and how monthly extra principal could change payoff time and scheduled interest.

Fixed-rate mortgage estimate

Enter the mortgage interest rate, not APR. Currency changes display only. The formula divides the entered nominal annual rate by 12; it does not translate jurisdiction-specific compounding or disclosure conventions. Property tax, insurance, HOA, and mortgage insurance stay separate from principal and interest. An optional extra payment is applied only to principal in this model.

Purchase and loan

Currency

Home price ($)

Down payment (%)

Fixed annual interest rate (%)

APR can include fees and is not the rate used by this payment formula.

Loan term (years)

Optional extra principal

Compare the scheduled mortgage with an extra amount applied directly to principal after every monthly payment, starting in month one.

Extra principal per month ($)

Enter 0 for the scheduled plan. Confirm that your loan permits prepayment and that your servicer will apply the extra amount to principal.

Taxes, insurance, and association dues

Use current quotes or notices. These amounts can change after closing.

Annual property tax ($)

Annual homeowners insurance ($)

Monthly HOA or association dues ($)

Mortgage insurance input

Explore More Finance Tools

Continue with related pages to compare results and improve decision making.

View Finance Category Read the Mortgage Calculator Guide

How This Mortgage Calculator Works

This calculator models a level-payment fixed-rate mortgage, adds only the ownership costs and mortgage-insurance duration you enter, and compares the scheduled loan with an optional fixed amount of extra principal paid monthly from month one.

Formula and Calculation

The core formula used by this mortgage calculator is: Monthly principal and interest = P x r / (1 - (1 + r)^-n). Extra principal is applied after each scheduled payment, and scheduled interest saved = baseline interest - interest under the extra-payment schedule.

P is home price minus down payment, r is the fixed monthly rate, and n is the number of payments. Extra principal reduces the balance after that month’s interest, so it affects interest beginning with the next month. It does not recast or reduce the required scheduled payment.

On a $240,000 mortgage at 6.5% for 30 years, the scheduled principal-and-interest payment is about $1,516.96. Adding $200 of principal every month from month one produces a modeled payoff in 262 months instead of 360 and about $96,269.55 less scheduled interest.

Worked Examples

Monthly payment and entered housing costs

A $300,000 home with 20% down creates a $240,000 loan. At 6.5% for 30 years, scheduled principal and interest is about $1,516.96. Adding $300 monthly property tax and $100 monthly insurance gives an initial housing estimate of about $1,916.96.

Initial entered housing estimate: about $1,916.96 per month.

This excludes closing costs, maintenance, utilities, and any amounts not entered.

$200 monthly extra-principal comparison

For the same $240,000 loan at 6.5% for 30 years, apply $200 after every scheduled payment from month one.

Modeled payoff: 262 months; time saved: 98 months; scheduled interest saved: about $96,269.55.

This assumes monthly interest timing, no recast, and no fee or prepayment charge.

How to Use This Calculator

Enter home price and down payment as an amount or percentage.
Enter the fixed interest rate, not APR, and the loan term.
Add current property-tax, insurance, HOA, and mortgage-insurance figures if applicable.
Enter optional monthly extra principal, or leave it at zero for the scheduled plan.
Compare payoff months and scheduled interest, then review or export the active amortization schedule.

Why Use This Mortgage Calculator?

See how down payment changes loan amount and loan-to-value.
Separate amortized principal and interest from other monthly costs.
Compare scheduled payoff and interest with a consistent monthly extra-principal plan.
Export scheduled principal, extra principal, interest, and housing costs in separate columns.

Related Tools and Guides

Try the Loan Calculator for a related calculation.
Try the Compound Interest Calculator for a related calculation.
Read the Mortgage Calculator Guide for examples and assumptions.
Browse the Finance Calculators page for more tools.

Related Calculators

->Loan Calculator ->Compound Interest Calculator ->Property Tax Calculator

Frequently Asked Questions

What does a mortgage calculator include?

It estimates fixed-rate principal and interest, separately adds the property tax, home insurance, mortgage insurance, and HOA figures you enter, and can compare a consistent monthly extra-principal plan.

How much down payment should I enter?

Enter the amount or percentage you actually plan to pay. The calculator converts it to loan amount and initial loan-to-value; it does not decide what is affordable for you.

Does the calculator automatically decide when PMI ends?

No. Mortgage-insurance rules vary by loan and country. Enter a quoted monthly premium or annual rate and the duration from your lender disclosure.

Does paying extra principal lower the required monthly payment?

Not in this model. The scheduled principal-and-interest payment stays unchanged; the extra amount reduces balance and can shorten the payoff period. A lender-approved recast is a separate process and is not modeled.

How is mortgage interest saved with extra payments calculated?

The calculator builds one schedule without extra principal and another with the entered amount applied monthly from month one. It subtracts the second schedule’s interest from the baseline scheduled interest.

Should I check for a prepayment penalty?

Yes. Confirm that your loan permits extra payments, whether any charge applies, and that your servicer will apply the extra amount to principal. The displayed savings do not subtract fees or penalties.