Mortgage Calculator

Calculate monthly mortgage payments, total interest, and amortization schedule.

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Monthly Payment

$0

Total Interest $0
Total Amount $0

Overview

A mortgage is the largest installment loan most households will ever carry, and the monthly payment sits at the center of every housing budget. The calculator below turns the three numbers that actually drive that payment: loan principal, interest rate, and term, into a clean breakdown of monthly cost, total interest over the life of the loan, and a full amortization schedule (a table that shows how much of each payment goes to interest versus principal in every year).

The underlying math is the standard amortization formula. P is the principal after the down payment, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. Plug them in and the result is the same fixed payment that lenders quote, with a twist: in the early years almost all of it is interest, and in the final years almost all of it is principal. Flipping a 30-year loan to 15 years does not just cut the term in half, it usually cuts the total interest paid by more than two thirds.

Two related concepts show up in the inputs. LTV, or loan-to-value, is the loan amount divided by the home's appraised value. Put less than 20 percent down and most lenders add PMI (private mortgage insurance), which is an extra fee until equity reaches 20 percent. APR (annual percentage rate) bundles the rate with most closing costs into one number, which is the right figure to use when comparing two mortgage offers. Fixed-rate loans keep the same payment for the full term. Adjustable-rate mortgages (ARMs) start with a lower teaser rate, then reset periodically, which makes them harder to budget over decades.

The calculator is also useful for refinance checks, home equity lines of credit, and quick 'what if' tests, such as paying one extra month per year or rounding the payment up to the nearest hundred. Run it before talking to a lender and the conversation gets shorter and cheaper.

How to use

  1. Enter the home price, the down payment in dollars or percent, and the loan term in years (15, 20, or 30 are common).
  2. Enter the interest rate as a percentage, for example 6.75, and confirm property tax and home insurance if those are added to the monthly payment.
  3. Click calculate to see the monthly principal and interest, the full amortization schedule, and the total interest paid over the life of the loan.
  4. Re-run with a different term, an extra payment, or a different down payment to see how each lever changes the total cost.

Formula

M = P × [r × (1 + r)^n] ÷ [(1 + r)^n − 1], where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. Example: a $300,000 loan at 6.5% for 30 years has n = 360 and r = 0.005417, giving a monthly payment of about $1,896.

Interpreting your results

The monthly principal-and-interest figure is the headline number. Total interest is what the loan actually costs on top of the borrowed amount, and the amortization schedule shows how that cost shifts over time. In year 1 of a 30-year, 6.5% loan, roughly $1,625 of a $1,896 payment is interest; by year 20 the split is closer to $700 interest and $1,196 principal. Use the schedule to see the breakeven point for refinancing or for switching to a shorter term.

Frequently asked questions

How much house can I actually afford?
A common rule is that the monthly housing cost, including principal, interest, taxes, and insurance, should stay below 28 to 30 percent of gross monthly income. Lenders often quote a higher ceiling, but staying near 28 percent leaves room for taxes, maintenance, and a savings cushion.
Is 15-year or 30-year better?
A 15-year loan has a lower rate and dramatically less total interest, but a much higher monthly payment. The right answer depends on cash flow. If the monthly payment fits comfortably, a 15-year is usually the cheaper loan. If it strains the budget, a 30-year with extra voluntary payments is a flexible middle path.
What is PMI and when does it go away?
Private mortgage insurance is required when the down payment is below 20 percent. It typically costs 0.5 to 1.5 percent of the loan balance per year and is added to the monthly payment. It drops off automatically once the loan balance reaches 78 percent of the original value, or sooner with a reappraisal.
Should I pay points to buy down the rate?
Points are prepaid interest, where one point equals 1 percent of the loan. Buying points makes sense when the lower payment is kept long enough to recover the upfront cost. A simple test: divide the point cost by the monthly savings to get the break-even months, then check that the stay in the home is longer.

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