InstaCalcs

Mortgage Calculator

Estimate the principal-and-interest payment on a fixed-rate mortgage. Change the price, down payment, rate, or term and see how the monthly payment moves.

By InstaCalcs Team·Reviewed April 25, 2026·Report an issue

Monthly Payment

$1,769.79

Loan Amount

$280,000.00

Total Interest

$357,124.57

Total Payment

$637,124.57

Payment Breakdown

Principal: $280,000.00 Interest: $357,124.57

How to use

Enter the home price, down payment, annual interest rate, and loan term. The calculator shows the monthly principal-and-interest payment, total paid over the loan, and how much of that total is interest.

Formula

M = P[r(1+r)^n] / [(1+r)^n - 1]

Where M is the monthly payment, P is the loan principal (home price minus down payment), r is the monthly interest rate (annual rate / 12), and n is the total number of payments (years × 12). This formula calculates a fixed monthly payment that fully amortizes the loan over the specified term.

When this calculator helps

Mortgage quotes can feel weirdly abstract until you put them next to the monthly payment. This calculator is useful when you are comparing a 15-year and 30-year loan, testing a bigger down payment, or checking how painful a higher rate would be. It does not include every housing cost. Taxes, insurance, HOA fees, and repairs still need their own line in the budget.

Examples

Example 1: Starter Home

A $250,000 home with 10% down ($25,000) leaves a $225,000 loan. At 6.5% for 30 years, the monthly payment is $1,422. Over the full term, you pay $511,920 total, meaning $286,920 goes to interest. With PMI at $125/month (since under 20% down), the real monthly cost is $1,547 until you reach 20% equity.

Example 2: 15-Year vs 30-Year Comparison

On a $400,000 home with 20% down ($320,000 loan) at 6.5%: a 30-year mortgage costs $2,023/month ($728,280 total). A 15-year mortgage at 5.75% costs $2,653/month ($477,540 total). The 15-year option costs $630 more monthly but saves $250,740 in total interest.

Example 3: Impact of a Larger Down Payment

For a $350,000 home at 7%: putting 5% down ($332,500 loan) costs $2,212/month plus $166/month PMI. Putting 20% down ($280,000 loan) costs $1,863/month with no PMI. The larger down payment saves $515/month and $115,400 in total interest over 30 years.

Things to watch

  • •Your total housing cost includes property taxes, homeowner's insurance, and possibly HOA fees, budget 1-2% of home value annually for taxes and insurance combined.
  • •Keep your total housing payment (including taxes and insurance) below 28% of gross monthly income, this is the guideline most lenders use.
  • •Get pre-approved before house hunting to know your true budget and strengthen your offers in competitive markets.
  • •A 0.5% difference in interest rate on a $300,000 loan changes your monthly payment by about $90 and total interest by over $32,000 over 30 years.
  • •Budget 1-3% of the home's value annually for maintenance and repairs, this often-forgotten cost can add $250-$750/month for a typical home.

Sources and methodology

Last reviewed: April 25, 2026. We review formulas, default assumptions, and examples against public references when a formal source applies.

Method: This calculator uses the formula explained on this page, then checks default assumptions and examples against the references listed below.

Found something off? Send a correction with the page URL, inputs, result, and expected result.

Common questions

How is a monthly mortgage payment calculated?
Your monthly mortgage payment is calculated using the loan amount, interest rate, and loan term. The formula is M = P[r(1+r)^n]/[(1+r)^n - 1], where P is the principal, r is the monthly interest rate, and n is the total number of payments. This creates a fixed payment that covers both principal and interest.
Should I choose a 15-year or 30-year mortgage?
A 15-year mortgage has higher monthly payments but saves you tens of thousands in interest. A 30-year mortgage has lower payments, giving you more monthly flexibility. For example, a $300,000 loan at 7% costs about $479,000 total over 30 years versus $388,000 over 15 years, a $91,000 difference.
How much down payment do I need?
Conventional loans typically require 3-20% down. FHA loans allow as low as 3.5%. VA and USDA loans may require 0% down. A 20% down payment avoids private mortgage insurance (PMI), which can add $100-300/month to your payment.
What are closing costs and how much should I expect?
Closing costs typically range from 2-5% of the home purchase price and include loan origination fees, appraisal, title insurance, attorney fees, and prepaid taxes/insurance. On a $350,000 home, expect $7,000-$17,500 in closing costs. Some sellers may agree to cover part of these costs during negotiations.
How does making extra mortgage payments help?
Extra payments go directly to reducing the principal balance. Paying just $100 extra per month on a $300,000 mortgage at 7% for 30 years saves about $66,000 in interest and pays off the loan nearly 5 years early. Even one extra payment per year can shave 4-5 years off a 30-year mortgage.