Finance

Mortgage Calculator with Extra Payments

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Use this mortgage calculator with extra payments to estimate your base monthly payment, then model how one-time or recurring principal prepayments shorten your loan and cut total interest. Enter home price, down payment, rate, and term, then compare scenarios before committing to a payoff strategy.

Extra payments go straight to principal on most fixed-rate loans, which means every dollar above the required payment reduces future interest. Even modest monthly additions—$100 or $200—compound over a 30-year term.

This calculator combines full mortgage inputs (home price, down payment, taxes, and insurance) with extra-payment payoff modeling so you do not need to switch between separate tools.

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Your data never leaves your computer.

How to use this tool

Enter home price, down payment, interest rate, and loan term. Optionally add property tax, insurance, and HOA fees, then enter your planned extra monthly payment toward principal. Calculate to see baseline payments and prepayment savings on one page.

Worked example

Example: a $360,000 loan at 6.5% over 30 years has a base payment near $2,275/month. Adding $200/month in extra principal can save tens of thousands in interest and shorten the term by several years.

When to use this

Planning whether to apply a bonus or tax refund to your mortgage.
Comparing minimum payments versus a fixed extra amount each month.
Checking baseline P&I before opening a dedicated payoff spreadsheet.
Deciding if a 15-year term beats a 30-year loan plus voluntary prepayments.

Common mistakes

Assuming extra payments automatically shorten the term without telling your servicer to apply them to principal.
Prepaying low-rate mortgage debt while carrying high-interest credit card balances.
Forgetting that escrow for taxes and insurance does not change when you add principal.
Ignoring prepayment penalties on some non-standard loan products.

calculate interest saved with $100 extra per month
compare biweekly vs monthly extra payments
see payoff date after annual lump sum
model one extra payment per year
decide between extra payments and investing

How it works

Enter home price, down payment, interest rate, and loan term to calculate your baseline principal-and-interest payment and optional tax, insurance, and HOA costs. Add an extra monthly principal payment to see interest saved, months shaved off the loan, and a balance chart comparing standard vs accelerated payoff.

Limitations

Monthly payment estimates exclude HOA, PMI changes, escrow adjustments, and property tax reassessments. Not a loan offer or pre-approval.

Privacy and file handling

Your data is processed in your browser and is not uploaded to our server.

Accuracy & methodology

This section documents how the calculator works, what it leaves out, and when results were last reviewed. Figures are educational estimates—not professional advice—and are not labeled "current" unless tied to automatically updated reference data.

Formula source or methodology: Loan amount = home price − down payment. Monthly principal & interest uses the standard amortizing loan payment formula (same as loan calculator). Optional annual property tax, insurance, and HOA are divided by 12 and added to P&I for total monthly housing payment.
Jurisdiction: General mortgage math (not country-specific underwriting rules)
Unit system: Currency for price, down payment, tax, insurance, HOA; years for term; percent for rate
Rounding method: Currency amounts round to two decimal places (half up via Math.round × 100 / 100).
Assumptions: Fixed annual interest rate for the full term
Level monthly payments (fully amortizing)
Down payment is a dollar amount, not a separate percent field
Known omissions: Not tax, legal, investment, or lending advice. Confirm material decisions with qualified professionals.
Origination fees, points, PMI/MIP, and lender-specific charges unless a field exists
Property taxes, insurance, and HOA unless explicitly entered
Prepayment penalties and variable or adjustable rates after the initial period
Tax deductibility of interest
Test cases (automated): Typical home price, down payment, rate, and term return positive P&I and total interest
Down payment greater than home price is rejected
Version & last verified: Logic version 1.0. Content and formulas last verified 2026-07-06.

Results are estimates for educational purposes and are not financial advice. Taxes, insurance, HOA fees, and lender-specific costs may not be included. Consult a qualified financial professional for personal guidance.

Related Mortgage Calculator guides

These pages use the same mortgage calculator with guides tailored to specific search intents.

Frequently asked questions

How do extra payments affect my mortgage?

Extra payments applied to principal reduce the balance faster, which lowers total interest and shortens the loan term. This calculator shows your baseline payment and quantifies interest and months saved from your extra amount.

Should I make extra payments or invest instead?

That depends on your mortgage rate, tax situation, and alternative returns. This tool helps you quantify interest savings from prepaying—it does not provide investment advice.

Does this calculator show an amortization schedule with extras?

This page shows baseline payments, prepayment savings, and a balance-over-time chart comparing standard vs extra-payment paths. For a downloadable amortization table, use the mortgage amortization calculator linked below.