Mortgage Calculator

What Mortgage Calculator helps you do

Estimate principal and interest, then optionally add property tax, insurance, PMI, HOA and other monthly costs for a full housing-cost view. The loan amount is the home price minus the down payment, and the payment uses the reducing-balance formula. Advanced mode also accepts an extra monthly payment and shows the amortization schedule.

The estimate runs in your browser and your figures are not uploaded to Haivix.

How it works

These calculators apply standard finance formulas to the numbers you enter. Loans use the reducing-balance annuity formula, where the monthly rate is the annual rate divided by twelve and each payment covers that month's interest before reducing principal. Savings projections compound at the same monthly rate and treat contributions as arriving at the end of each period. Amounts are rounded to the currency's minor unit, with the final payment adjusted so the balance reaches zero. Nothing is fetched from a bank, credit bureau or rate feed, so the result is only as good as the inputs.

How to use Mortgage Calculator

1. Enter the home price, down payment, rate and term.
2. Add tax, insurance, PMI, HOA and other costs in advanced mode.
3. Review the principal-and-interest payment and the total housing cost.
4. Download the amortization CSV if you want the full schedule.

When to use it

• Estimate a monthly housing payment before house-hunting.
• Compare the impact of different down payments and rates.
• See how much of the payment is tax and insurance rather than the loan.
• Check how an extra payment shortens the term.
• Compare a 15-year and a 30-year term on total interest.
• Prepare a budget before requesting a lender quote.

When not to use it

• Do not use it for an adjustable-rate mortgage that changes after a fixed period.
• Do not treat the estimate as an approval or a closing-cost quote.
• Do not ignore local tax and insurance rules; the inputs are yours.

Example

A 350,000 home with a 70,000 down payment leaves a 280,000 loan. At 6.25% over 30 years the principal-and-interest payment is about 1,724 per month, and total interest is roughly 341,000. Adding 4,200 a year in tax and 1,440 in insurance raises the monthly housing cost by 470 without reducing the loan balance.

What you can do with Mortgage Calculator

• Calculate monthly principal and interest.
• Subtract the down payment from the home price.
• Add annual tax and insurance as monthly costs.
• Include PMI, HOA and other monthly amounts.
• Model an extra monthly payment.
• Show a balance chart, amortization table and CSV.

Example: compare total cost, not just the monthly figure

Check whether the quoted rate is flat or reducing. The same headline percentage can cost very differently depending on how interest is charged.

Confirm the term unit. A duration entered in months instead of years changes the payment by an order of magnitude.

Look at total interest as well as the monthly payment. A longer term lowers the payment and raises the total cost.

Model one extra payment rather than assuming it. The amortization table shows how much of the saving comes from principal versus a shorter term.

Treat the output as an estimate. Fees, insurance, taxes, variable rates and lender rounding can all move the real figure.

Do not treat a calculator as financial advice. For a binding quote, use the lender's own disclosure.

Check the currency and its minor units. The math is currency-agnostic, but formatting, rounding and the number of decimal places change the displayed result.

Write down the rate, term and assumptions you used. A later comparison is only meaningful if both runs share the same basis.

What to know before you start

• It does not look up local tax or insurance rates; you supply them.
• Local rules, closing costs and lender fees are outside the calculation.
• It assumes a fixed rate for the whole term.
• PMI is entered as a flat monthly amount, not as a percentage that drops off automatically.

Common mistakes

• Entering the home price as the loan amount.
• Adding annual tax as a monthly figure.
• Expecting PMI or HOA to reduce principal.
• Forgetting that a longer term lowers the payment but raises total interest.

Troubleshooting

If the down payment error appears, it must be less than the home price.

If the payment looks too high, check whether the rate is annual rather than monthly.

If the total housing cost is unchanged, the advanced costs may still be zero.

If the payoff date is wrong, check the start date field.

Related standards and documentation

• ISO 4217 defines currency codes and minor units.
• US Truth in Lending (Regulation Z) governs APR disclosure for consumer credit.
• The EU Consumer Credit Directive (2008/48/EC) defines the annual percentage rate of charge.
• The standard annuity formula relates principal, periodic rate, payment and number of periods.
• ISO 8601 defines the date and duration formats used by the schedule.