Mortgage Calculator — Payments, Interest, and Amortization

This mortgage calculator estimates mortgage payments, remaining balance, and total interest over the full amortization period based on your inputs.

Enter your home price, down payment, interest rate, and amortization to see how payments and costs evolve over time.

This calculator can be used to answer:

How much interest will I pay on my mortgage?
How long will it take to pay off my mortgage?
What is the total amount paid in principal and interest?
How do changes in interest rate affect payments and total interest?

No opinions. No hidden assumptions. Just arithmetic.

Inspect the Arithmetic

Inputs

Home price ($)

Down payment

Down payment amount ($)

Interest rate (APR %)

Amortization period (years)

Payment frequency

Price Down payment Interest rate Amortization

Home price

$500,000

Outputs

Payment amount

$–

Loan amount

$–

Total interest paid

$–

Total paid

$–

Payoff time

–

Amortization Graph

Remaining principal

Cumulative interest paid

With these inputs:

$– paid upfront as a down payment
$– repaid in mortgage principal
$– paid in mortgage interest
$– total cost of the home
(down payment + principal + interest)

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▼ First 12 months — monthly amortization

Payment #	Payment amount	Interest portion	Principal portion	Remaining balance

▼ Full amortization — annual summary

Year	Total payments	Total interest	Total principal	Ending balance

Disclaimer: All content on The Long Math — including articles, essays, calculators, tools, or any other material — is provided solely for educational and informational purposes and does not constitute financial, tax, legal, or investment advice. Any results or projections are based on simplified models, assumptions, and user-supplied inputs and may not reflect real-world outcomes. You are responsible for evaluating the accuracy and applicability of the information provided and for conducting your own due diligence. Before making financial decisions, consult a qualified professional.