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The monthly cost of owning a home in the US is called PITI: principal, interest, taxes and insurance. The last two are usually collected by the lender into an escrow account and paid on your behalf, so they leave your account as part of one payment.

Principal and interest come from the standard amortisation formula, which fixes the payment and shifts the mix over time — mostly interest early, mostly principal late. On a $420,000 home with 20% down at 6.5% over 30 years, that portion is about $2,124 a month.

If the down payment is under 20%, private mortgage insurance is added on top, typically 0.3-1.5% of the loan per year charged monthly. It must fall away automatically once the balance drops below 78% of the original value, so this calculator also shows how many months away that is.

Budgeting from principal and interest alone understates the real cost by more than 30%. On that $420,000 home, $2,124 becomes $2,659 once $385 of property tax and $150 of insurance are added, before any HOA dues.

Using a national average property tax rate goes badly wrong locally. Counties above 2% are common in New Jersey and Illinois while Hawaii sits near 0.3%. On the same house that is the difference between $1,300 and $8,800 a year.

Putting down less than 20% is not itself a mistake, but leaving PMI out of the budget means $100-300 a month arriving unplanned. If you are close to 20%, use this calculator to compare saving longer against buying now.

The gap between 30 and 15 years is not only the monthly payment. On $420,000 at 6.5%, thirty years costs roughly $429,000 in interest while fifteen costs about $191,000. The shorter term costs nearly $1,000 more a month and less than half as much in total.

Each percentage point of rate cuts roughly 10% off the house price you can buy at the same monthly payment. Setting your ceiling here before viewing anything makes it far easier to walk away from a listing above it.

Principal and interest depend only on the loan amount, the rate and the term. The table shows them for a $400,000 loan — for example, a $500,000 home with 20% down — worked out the same way this calculator does it. Property tax, insurance, PMI and HOA dues come on top.

Across these rates a 15-year term raises the monthly payment by 33–44% and cuts the total interest by 55–56%. Each half point of rate moves the 30-year payment by $127–$136 a month at this loan size.

Federal rules for conventional loans on a principal residence closed on or after July 29, 1999 give you two dates. You can ask your servicer in writing to cancel PMI once the balance is scheduled to reach 80% of the home's original value, if your payments are current, there is no second lien and the value has not fallen. The servicer must end it automatically when the balance is scheduled to reach 78%, and in any case the month after the loan's midpoint — 15 years into a 30-year loan.

Original value generally means the lower of the purchase price and the appraisal at purchase. Extra principal payments bring the request date forward. FHA and VA loans follow their own mortgage insurance rules. This calculator reports the automatic 78% date; the table adds the earlier date on which you can ask.

Most lenders collect property tax and homeowners insurance with the monthly payment, hold it in an escrow (impound) account and pay the bills when they come due. Those bills change from year to year, so the escrow part of the payment changes too; on a fixed-rate loan only principal and interest are fixed.

Without escrow you pay those bills yourself, usually in one or two large installments. Missing property tax can bring penalties, a tax lien and eventually foreclosure, and if homeowners coverage lapses the lender can buy force-placed insurance and bill you for it, which usually costs more.