What is this calculator for?
You're about to submit an offer on a $485,000 house. You know the seller wants 20% down, you know rates are around 6.875% as of late 2025, and you need to know if your monthly payment will actually fit your budget — not just the principal and interest, but the property tax, insurance, PMI if applicable, and HOA. The mortgage calculator turns four numbers (price, down payment, rate, term) into the single monthly figure that will hit your account every month for the next 30 years.
A US mortgage payment has up to five components: principal (paying down the loan), interest (the cost of borrowing), taxes (county property tax, escrowed monthly), insurance (homeowner's hazard insurance, also escrowed), and PMI (private mortgage insurance if down payment under 20%). The acronym PITI captures the first four; PMI adds the fifth. The "monthly mortgage payment" people quote often refers only to P&I, which understates true monthly housing cost by 25-40%.
This calculator handles the full PITI math. Enter your home price, down payment, mortgage rate, term, and the calculator will use typical assumptions for property tax (state-specific defaults, adjustable), homeowner's insurance, PMI (auto-calculated based on down payment), and optional HOA. Output: monthly P&I, monthly PITI, total interest over the life of the loan, and a year-by-year amortization showing how much of each payment is principal vs interest.
How to use this calculator
Enter the home price as your realistic purchase offer. Don't use the listing price unless you know it's where the deal will close — Zillow's "Zestimate" is rough; Redfin's recent sold-comp data is far more accurate for setting offer prices.
Down payment: 20% is conventional and avoids PMI; under 20% requires PMI. Common alternatives: 3-5% conventional with PMI; 3.5% FHA with FHA mortgage insurance (lasts longer than conventional PMI); 0% VA (military-eligible) or USDA (rural areas). The calculator accepts any percentage; if under 20%, it automatically adds PMI to the monthly estimate at typical rates (0.5-1% of loan balance annually, declining over time as you build equity).
Mortgage rate should be the current quoted rate from a real lender, not the headline national average. As of late 2025, 30-year conventional rates run 6.5-7.5% depending on credit score, down payment, and lender. FHA rates are typically 0.25-0.5% lower than conventional. VA rates are typically the lowest available. Get rate quotes from 3-4 lenders before locking; the rate spread on the same loan often spans 0.5+ percentage points.
Loan term: 30 years is the US default and produces lower monthly payments. 15 years has higher monthly payments but cuts total interest by ~60%. 20- and 25-year terms exist but are uncommon. The calculator shows total interest by term — the 15-vs-30 trade-off is one of the biggest decisions in home buying.
Property tax rate: the calculator defaults to your state's effective average but is adjustable. Look up your specific county on the assessor's website for accuracy. Homeowner's insurance defaults to typical $1,200-2,800 annual range; high-risk areas (FL hurricanes, CA wildfire, TX hail) can be $3,500-8,000+. HOA is optional — enter monthly dollar amount for condo/PUD properties.
Understanding your results
The calculator returns monthly P&I, monthly PITI (P&I + tax + insurance + PMI), monthly all-in cost (PITI + HOA), total interest over loan term, and total amount paid (loan + interest). The amortization breakdown shows year-by-year principal vs interest split.
The total-interest number is usually the shock. A $388,000 mortgage at 6.875% for 30 years has a $2,547 monthly P&I, $562,000 in total interest over the life of the loan, and $950,920 total paid. Over three decades, you pay $562K to borrow $388K — more than the loan amount. Inflation softens this in real-dollar terms (your $2,547 payment in 2055 has the purchasing power of about $1,000 in today's dollars at 3% inflation), but the nominal hit is large.
The PITI-to-income ratio is the key affordability check. Lenders typically want PITI under 28% of gross monthly income (front-end DTI). At $185K household income, 28% of monthly gross is $4,317/month — a $388K mortgage with PITI of $3,683/month sits at 23.9%, comfortable. At household income $110K, 28% of monthly gross is $2,567 — the same mortgage at $3,683 is 40%, which lenders typically reject or approve only with substantial reserves. Run your specific income through the calculator before targeting a home price range.
The 15-vs-30-year decision. On the same $388K loan: 30-year at 6.875% has P&I $2,547/month, $562K interest. 15-year at 6.25% (typical 15-year discount) has P&I $3,328/month, $211K interest. The 15-year saves $351K in total interest at a cost of $781/month higher payment. The hidden case for 30-year: the difference in monthly payment ($781) invested in stocks at 7% real over 30 years compounds to roughly $800K — meaningfully more than the interest savings. The 30-year-with-investment wins mathematically if you actually invest the difference; the 15-year wins if you don't.
The reset-clock trap. Refinancing into a new 30-year mortgage 7 years into your original 30-year resets your principal-vs-interest schedule — you're back to year 1 of front-loaded interest. Refinancing makes sense when the rate drop pays for closing costs within your expected remaining time in the home, but the term reset means you can pay significantly more total interest unless you make extra principal payments to catch up to your old amortization schedule.
A worked example
Anika and Raj, 33 and 35, household income $215,000, shopping for a first home in suburban Raleigh. They've saved $97,000 for down payment plus closing costs. Two scenarios they're evaluating:
Scenario A: $475,000 home, 18% down ($85,500), finance $389,500 at 6.875% 30-year. Closing costs: about $11,000. Total cash to close: $96,500. PMI required (down payment under 20%): about $195/month. Property tax (Wake County 0.86%): $340/month. Insurance: $135/month. Monthly P&I: $2,562. Monthly PITI: $3,232. Annual housing cost: $38,784.
Scenario B: $445,000 home, 20% down ($89,000), finance $356,000 at 6.875% 30-year. Closing costs: $10,000. Total cash: $99,000 — slightly tight, requires liquidating savings buffer. No PMI. Property tax: $319/month. Insurance: $128/month. Monthly P&I: $2,341. Monthly PITI: $2,788. Annual housing cost: $33,456.
Scenario B's PITI is $444/month lower ($5,328/year) primarily because of the $195/month PMI elimination plus the smaller loan. Over 30 years, Scenario A's higher PMI period (~5-7 years until they hit 20% equity) costs them about $13,500 in PMI premiums. Plus the larger loan generates more total interest. Total cost difference over 7 years (until PMI drops on Scenario A): about $35,000 favoring Scenario B.
The trade: Scenario A buys a $30K nicer house (better neighborhood, extra bedroom, or whatever the $30K buys). Whether that $30K is worth $35K of extra cost over 7 years depends on their priorities. Some couples would gladly pay the premium for the better property; others would prefer the cleaner balance sheet of Scenario B.
One more variation: same Scenario A but they take the 15-year mortgage at 6.25%. P&I: $3,341/month. PITI: $4,011. Annual: $48,132. They save $230K in total interest over the life of the loan but increase monthly cost by $779/month. Their DTI math: $4,011 PITI on $17,917 monthly gross = 22.4% — well within the 28% front-end limit. If they can absorb the cash flow hit and don't need extreme retirement savings flexibility, the 15-year is the cleanest mathematical win. If they want to max retirement at 22%+ of income, the 30-year preserves cash flow for retirement contributions and they net out roughly even.
State-by-state variations
Property tax dominates the state-by-state mortgage math. New Jersey, Illinois, Texas, and Vermont have property tax rates 3-5x those of Hawaii, Alabama, and Colorado. On the same $475,000 home: $9,500/year property tax in NJ ($792/month) versus $1,330/year in HI ($111/month). Property tax is the single largest mortgage-payment variable across geographies.
State laws affecting mortgages: California's deed of trust system (no judicial foreclosure required, faster process for lenders) versus New York's judicial foreclosure (typically 2-3 years). Texas's homestead protections limit creditor reach into your primary residence (one of the strongest in the country). Some states (NY, NJ, MA) impose mortgage recording tax — typically 0.5-2% of loan amount paid at closing, on top of standard closing costs. Florida has documentary stamp tax on mortgages (0.35% of loan). These state-level taxes can add $1,500-7,000 to closing costs depending on loan size and state.
Insurance varies dramatically by geography. Florida homeowner's insurance has roughly doubled since 2018 due to hurricane exposure — annual premiums of $4,500-7,500 for typical homes are common, with some properties unable to find private insurance and resorting to the state's Citizens Property Insurance. California's wildfire exposure has created similar pressures in fire-zone areas; some insurers have stopped writing new policies in CA entirely. Coastal Texas and Louisiana have hail and hurricane exposure that raises premiums significantly. Inland mid-Atlantic and Midwest typically have the lowest insurance premiums.
VA loans (zero down payment for eligible military and veterans) have additional state-by-state benefits. Some states (CA, OR, WI) offer state veteran home loan programs that supplement federal VA benefits. Texas Veterans Land Board offers below-market rates for veterans. These programs can stack with federal VA loans for further savings.
Related resources
For the underlying loan-payment math, see Loan Amortization Calculator. For evaluating whether you qualify for the loan in the first place, the DTI Ratio Calculator. For the rent-versus-buy decision, Buy vs Rent. For state-specific property tax impact, the Property Tax Calculator. The CFPB's Owning a Home resource covers the federal mortgage process and protections under TILA-RESPA in plain language.