Mortgage Calculator

What Is a Mortgage?

A mortgage is a long-term loan secured by the home you are buying. The lender holds a lien on the property until the loan is paid in full, which is what gives a 30-year fixed-rate borrower the right to lock in a single interest rate today and pay the same principal-and-interest amount every month for three full decades. According to the Consumer Financial Protection Bureau, the average U.S. home purchase involves a mortgage that lasts 30 years, makes 360 monthly payments, and ends with the borrower owning the property outright. Understanding how those payments are calculated is the foundation of every smart real-estate decision.[1]

For the week ending in early May 2026, the Freddie Mac Primary Mortgage Market Survey reports a 30-year fixed-rate mortgage averaging in the mid-6% range, with 15-year fixed loans about 70 basis points lower. The Federal Reserve H.15 statistical release shows that 30-year mortgage rates closely track the 10-year Treasury yield plus a roughly 200-basis-point spread that reflects credit risk and prepayment risk priced by mortgage-backed-securities investors. When you plug a rate into the calculator above, you are using the same arithmetic that lenders use to size your monthly obligation.[2, 3]

Mortgages are also where most middle-class wealth in the United States is built. The CFPB explains amortization as the process by which each monthly payment chips away at both the interest owed and the loan balance, with the principal share growing every month while the interest share shrinks. The chart and amortization schedule above visualize this curve so you can see exactly when your equity catches up to your interest cost — a critical insight for both first-time buyers and homeowners weighing a refinance.[5]

The Mortgage Payment Formula

The closed-form annuity formula behind every fixed-rate mortgage is PMT = P × r(1+r)ⁿ / ((1+r)ⁿ − 1), where P is the loan amount (home price minus down payment), r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (years × 12). On a $320,000 loan at a 7% annual rate over 30 years, this works out to roughly $2,128.99 per month — the figure shown in the KPI cards above. The calculator uses decimal.js 28-digit precision to avoid the rounding drift that creeps into spreadsheet implementations after a few hundred iterations.

Each month the lender applies the periodic rate to your remaining balance to compute the interest portion, deducts that from your fixed payment, and applies the rest to principal. In month one of a 30-year, 7% mortgage, roughly 88% of your payment goes to interest and only 12% to principal. By month 240, that ratio inverts, and by the final year nearly every dollar is principal. This is the front-loaded interest behavior captured in the chart above and is the reason early extra principal payments are dramatically more impactful than late-cycle ones.

PITI Explained: Principal, Interest, Taxes, and Insurance

PITI stands for Principal, Interest, Taxes, and Insurance — the four components most lenders include when sizing the housing payment used in qualifying ratios. Property tax and homeowner's insurance are typically collected by the servicer through an escrow account, billed monthly alongside principal and interest, and then disbursed to the taxing authority and insurer when due. Toggling "Include taxes, insurance & HOA" on the calculator above adds these escrow components to the displayed payment so the number you see matches what the servicer actually withdraws from your account.[6]

Property tax rates vary widely by jurisdiction. The national average effective rate hovers near 1.1% of assessed value, but it ranges from 0.3% in Hawaii to over 2% in New Jersey, Illinois, and parts of Texas. Homeowner's insurance averages roughly $1,500 per year nationally but can exceed $5,000 in coastal Florida or wildfire-prone regions of California. HOA fees, when applicable, can add anywhere from $50 to over $1,000 per month depending on the community. Plug the actual figures from your Loan Estimate disclosure into the calculator above to see your full PITI obligation, not just the bare P&I.[7, 8]

Why does the distinction matter? Because lenders cap your debt-to-income ratio (DTI) using PITI, not bare principal and interest. A buyer with a $2,100 P&I but $700 of property tax and insurance has a $2,800 housing burden, and the qualifying-ratio math at most lenders will flag DTIs above 43% as a problem under the qualified-mortgage rules. Failing to estimate PITI accurately is one of the most common reasons closings get delayed or restructured at the last minute.[9]

Down Payments and Private Mortgage Insurance (PMI)

When you put less than 20% down on a conventional conforming mortgage, the lender requires private mortgage insurance (PMI). PMI is a policy that protects the lender — not you — against losses if you default early in the loan. Annual premiums typically range from 0.3% to 1.5% of the original loan amount, with the exact rate driven by your credit score, loan-to-value ratio (LTV), and whether the loan is adjustable or fixed. On a $360,000 loan at 0.5%, PMI adds $150 per month — a meaningful drag on cash flow until the policy can be removed.[10]

The good news is that PMI is not permanent. The federal Homeowners Protection Act of 1998 (HPA) requires the servicer to automatically terminate PMI on the date the loan balance reaches 78% of the original property value, based solely on the original amortization schedule, as long as you are current on payments. Borrowers can also request cancellation at 80% LTV. The calculator above models the auto-termination rule by zeroing out the PMI line item once your principal payments have brought the loan-to-home-price ratio to or below 78% — for a 10% down payment loan, this typically happens around year 8 or 9.[11]

There are alternatives to PMI worth understanding. A piggyback "80-10-10" structure splits the financing into a primary 80% mortgage, a 10% second lien (a HELOC or home-equity loan), and a 10% cash down payment, avoiding PMI entirely at the cost of a higher blended rate on the second mortgage. VA loans for eligible veterans require no PMI and no down payment, replacing those costs with a one-time funding fee. FHA loans use Mortgage Insurance Premium (MIP) instead of PMI, but FHA MIP is generally non-cancellable for loans originated after June 2013, making the math less attractive than conventional PMI for borrowers with strong credit.[17, 18]

Fixed-Rate vs. Adjustable-Rate Mortgages

A fixed-rate mortgage locks the interest rate for the entire term, so the principal-and-interest portion of your payment never changes. About 90% of U.S. homebuyers choose a 30-year fixed-rate loan because predictability simplifies long-term budgeting and eliminates the risk of payment shock if rates rise. The trade-off is that fixed-rate borrowers typically pay a slight premium versus comparable adjustable products, since the lender is bearing the interest-rate risk for three full decades.

An adjustable-rate mortgage (ARM) starts with a fixed introductory rate — commonly 5, 7, or 10 years — then resets periodically based on a benchmark index plus a fixed margin. The 5/1 ARM, for example, fixes the rate for five years and then adjusts annually thereafter. ARMs come with rate caps that limit how much the rate can change at each adjustment and over the life of the loan. The CFPB warns that low introductory ARM rates often look attractive but can cost borrowers thousands more than a fixed-rate alternative if rates rise during the adjustment period.[12, 13]

When does an ARM make sense? When you have high confidence the loan will be paid off, refinanced, or the home sold before the first reset — typical scenarios include short military assignments, planned career relocations, or buyers expecting a meaningful liquidity event. Run the introductory rate through the calculator above as if it were a 30-year fixed to see your starting payment, then sensitivity-test the worst-case post-reset rate (the introductory rate plus the periodic and lifetime caps) to make sure you can still afford the loan if rates spike. Borrowers who skip that stress test are exactly who the CFPB has in mind when it cautions against ARM teaser rates.

The 2026 Mortgage Rate Environment

The Federal Reserve held the federal funds rate in a 3.50–3.75% target range at its March 18, 2026 FOMC meeting by an 11-to-1 vote (Governor Stephen Miran dissented in favor of a 25-basis-point cut), with the dot plot projecting one further cut by year-end and another in 2027. The next FOMC meeting is scheduled for May 6–7, 2026. Mortgage rates do not follow the federal funds rate one-for-one — they track the 10-year Treasury yield (FRED series DGS10), which itself reflects market expectations for short-rate paths plus a term premium and inflation expectations. Per the Freddie Mac Primary Mortgage Market Survey, the 30-year fixed averaged 6.30% for the week ending April 30, 2026 (up from 6.23% the prior week, down from 6.76% one year earlier). The 15-year fixed sat near 5.55%, and 5/1 ARM introductory rates ran roughly 50 basis points below the 30-year fixed.[4, 30, 2, 28]

Within those averages, the rate you qualify for depends on your credit score, debt-to-income ratio, loan-to-value ratio, and the loan product. Borrowers with FICO scores above 760, DTI under 36%, and 20% down typically secure rates 30–60 basis points below the headline PMMS average. The CFPB explainer on credit-score impact walks through how a 50-point FICO improvement can cut your monthly principal-and-interest by $30–$70 on a $300,000 loan — a difference worth pursuing before locking a rate. Use the CFPB Explore Interest Rates tool to see today's likely range based on your profile, then enter that range into the calculator above. For historical context, the FRED MORTGAGE15US series tracks the 15-year companion to MORTGAGE30US back to 1991.[39, 14, 29]

Loan Types Compared: Conventional, FHA, VA, and USDA

Most U.S. mortgages are conventional conforming loans — financed by Fannie Mae and Freddie Mac under the standardized underwriting in their Single-Family Selling Guide. The FHFA-published 2026 conforming loan limit for one-unit properties is $832,750 in most counties — a 3.26% YoY increase driven by FHFA's House Price Index methodology under HERA. High-cost areas (designated counties in California, New York, DC, and parts of Massachusetts and Hawaii) carry a ceiling of $1,249,125, which is 150% of baseline. Alaska, Hawaii, Guam, and the U.S. Virgin Islands receive the high-cost ceiling as their baseline, with their own high-cost ceiling at $1,873,675. Loans above these limits are "jumbo" loans held in lender portfolios and underwritten more conservatively.[35, 20]

FHA loans, insured by the Federal Housing Administration, suit borrowers with lower credit scores or smaller down payments. HUD News HUD No. 25-145 announced the 2026 FHA forward loan limits via Mortgagee Letter 2025-23, effective for case numbers assigned on or after January 1, 2026. The one-unit floor is $541,287 (65% of conforming baseline) and the high-cost ceiling matches conforming at $1,249,125. FHA loans require both an upfront mortgage insurance premium (1.75% UFMIP) and an annual MIP — most 30-year borrowers with 3.5% down pay 0.55% annually per HUD Mortgagee Letter 2023-05, which cut annual rates by 30 basis points in February 2023 and remains unchanged for 2026. Unlike PMI, FHA MIP usually persists for the life of the loan unless you put 10% or more down, in which case it terminates after 11 years.[22, 23, 24]

VA loans, guaranteed by the Department of Veterans Affairs and available to eligible service members, veterans, and surviving spouses, allow $0 down payment with no monthly mortgage insurance. The one-time VA funding fee replaces PMI: it is 2.15% for first-time use with less than 5% down, dropping to 1.50% for 5–9.99% down and 1.25% for 10%+ down. Subsequent-use buyers pay 3.30% on under-5%-down purchases. Veterans receiving VA disability compensation at any rating are exempt from the funding fee entirely. VA's streamline-refinance product, the Interest Rate Reduction Refinance Loan (IRRRL), requires only a 0.50% funding fee and minimal underwriting if the new rate is lower than the existing rate.[31, 32]

USDA loans, administered by USDA Rural Development under the Single Family Housing Guaranteed Loan Program (Section 502), finance 100% of the purchase price for low- and moderate-income borrowers buying in eligible rural and certain suburban areas. The 2026 income cap is generally 115% of area median income — about $119,850 for households of 1–4 members and $158,250 for 5+ in standard areas. A 1% upfront guarantee fee can be financed into the loan, and a 0.35% annual fee applies. Compare the four products against your situation: a borrower with 5% down, a 720 FICO, and stable W-2 income in a non-rural metro typically saves the most on conventional with PMI; a 620 FICO with 3.5% down picks FHA; a veteran with no down-payment cash picks VA; a moderate-income buyer in a USDA-eligible county can pick USDA for $0 down. The calculator above lets you toggle PMI, MIP-equivalent fees, and extra payments to compare lifetime costs.[33]

Underwriting Standards: DTI, Credit Score, and LTV

Mortgage underwriters evaluate three core ratios: debt-to-income (DTI), credit score, and loan-to-value (LTV). The CFPB defines DTI as monthly debt obligations divided by gross monthly income. Conventional loans typically follow the 28/36 rule: housing payment under 28% of gross income (front-end DTI) and total debt payments under 36% (back-end DTI). FHA permits up to 31/43 with manual underwriting flexibility on compensating factors (high reserves, large down payment, or strong residual income), and qualifying mortgages under the CFPB's Ability-to-Repay rule generally cap back-end DTI at 43%. VA uses a residual-income test rather than a hard DTI ceiling; the borrower must have specified after-housing income sufficient for family size and region.[9]

Minimum credit scores vary by loan product. Conventional loans set the floor at 620 FICO for most lenders, with the best pricing reserved for 740+; FHA accepts 580 FICO with 3.5% down and 500 FICO with 10% down per HUD's Single Family Housing Policy Handbook. VA does not publish a minimum but most lenders impose a 580–620 overlay. USDA generally requires 640. The CFPB explainer on credit scoring walks through the rate-bucket logic: lenders price in tiers (e.g., 740+, 720–739, 700–719), and a single tier of improvement before lock can save 12.5 to 25 basis points on the rate sheet. Pull your free annual reports at AnnualCreditReport.com, dispute errors at least 60 days before applying, and keep credit-card balances under 30% of available limits to avoid a utilization-driven score drop during underwriting.[39]

Loan-to-value (LTV) is the loan amount divided by the property's appraised value. LTV ≤ 80% (i.e., 20%+ down on a purchase) avoids PMI on conventional loans and qualifies for the lowest pricing tiers. LTV between 80–95% triggers PMI roughly 0.30–1.50% of loan value annually, with rate cards published by the major mortgage insurers (Enact, MGIC, Arch, Radian, National MI, Essent). LTV between 95–97% is supported by Conventional 97 (Fannie Mae) and Home Possible / HomeReady (covered in the next section). The Homeowners Protection Act of 1998 requires automatic PMI termination when scheduled LTV reaches 78% based on original amortization, and the borrower can request cancellation at 80% LTV with a clean payment history. Order an updated appraisal if your home has appreciated; an increase in value can push your LTV below 80% sooner than the amortization schedule predicts.[11]

First-Time Homebuyer Programs and Down-Payment Assistance

First-time buyers without 20% saved have several low-down-payment options. Conventional 97, available through Fannie Mae and Freddie Mac, allows a 3% down payment on a primary-residence purchase up to the conforming limit, with PMI required until 78% LTV. The borrower must complete a homebuyer-education course (often free online), and at least one borrower must not have owned a primary residence in the past three years. FHA 3.5% down is the lowest-credit-score path: 2026 FHA limits apply, MIP rules from HUD ML 2023-05 govern annual premiums, and the loan can be paired with state Housing Finance Agency (HFA) down-payment assistance for a near-zero-cash close.[22, 24]

For low-to-moderate-income borrowers, two affordable conventional products go even further than Conventional 97. Fannie Mae HomeReady and Freddie Mac Home Possible both allow 3% down and cap qualifying income at 80% of area median income (AMI) — a hard ceiling determined county-by-county and updated annually. Both products discount the PMI rate compared with standard Conventional 97 (often 50–100 basis points lower), accept gift funds for the entire down payment, and let non-occupant co-borrowers contribute to qualifying income. Use Fannie Mae's AMI Lookup Tool or Freddie Mac's Home Possible eligibility map to confirm property and income eligibility for your target address.[34, 36]

VA loans remain the only program offering true $0 down with no monthly mortgage insurance for eligible service members; the funding fee can be waived for veterans with VA disability ratings. USDA Section 502 matches that no-down-payment threshold for moderate-income buyers in eligible rural and suburban areas. Beyond the federal programs, every state operates a Housing Finance Agency offering down-payment-assistance grants, second-mortgage programs (sometimes forgivable), or below-market first-mortgage rates. HUD maintains a directory of state HFAs at hud.gov/states. Stack federal and state programs carefully — most allow stacking, but some lender overlays restrict combining DPA with low-down-payment products. Always ask the loan officer to model the all-in monthly cost (including any second-lien payments) before assuming a stacked offer beats a clean Conventional 97.[33]

Paying Down Faster: Extra Payments and Biweekly

Front-loaded interest math is what makes extra principal payments so powerful in the early years of a loan. On a $320,000, 30-year, 7% mortgage, adding $200 to every monthly payment shaves roughly 3.5 years off the term and saves about $76,000 in lifetime interest. Toggle "Add extra monthly payment" on the calculator above and watch the payoff date and interest savings KPIs update in real time. The earlier and the more consistent the additional principal, the larger the impact — a single $5,000 lump sum applied in year one saves more interest than the same $5,000 applied in year fifteen.

A popular alternative is the biweekly payment plan: split your monthly payment in half and pay every two weeks. Because there are 26 biweekly periods in a year (52 ÷ 2), this works out to 13 monthly payments per year instead of 12 — effectively one extra full payment per year, applied entirely to principal. Over a 30-year loan this typically shortens the term by 4–6 years. Just be sure your servicer applies the half-payment to principal rather than holding it in suspense and applying it once enough has accumulated; the Investopedia explainer on biweekly mortgages walks through the bookkeeping subtleties.

Always check for prepayment penalties before adding extra principal. Most modern conforming mortgages do not charge them, but some non-conforming jumbo, ARM, and subprime products still impose penalties on early payoff during a stated period (usually 1–3 years). Read your closing disclosure carefully — if the prepayment-penalty box is checked, ask the lender to walk you through the math before you accept the loan.

Mortgage Interest and Tax Deductibility

Mortgage interest on a primary or secondary residence is deductible on your federal return if you itemize, and the framework is now permanent. The One Big Beautiful Bill Act of 2025 (OBBBA, signed July 4, 2025 as Public Law 119-21) made the Tax Cuts and Jobs Act $750,000 acquisition-debt cap permanent. The cap had been scheduled to revert to the pre-TCJA $1 million ceiling on January 1, 2026, but no longer does. IRS Publication 936 applies that $750,000 cap ($375,000 for married filing separately) to acquisition debt originated after December 15, 2017; mortgages secured before that date remain grandfathered at the older $1 million cap. Home-equity debt is deductible only when the proceeds are used to buy, build, or substantially improve the home that secures the loan.[19, 16]

OBBBA also restored the deduction for private mortgage insurance premiums starting in tax year 2026, after the original TCJA had let it lapse following 2021. PMI on conventional loans, FHA annual MIP, USDA guarantee fees, and VA funding fees are once again treated as qualified residence interest under the statute, subject to income phase-outs at higher AGI levels. For a buyer paying $1,800–$2,400 annually in PMI on a sub-20%-down conventional loan, the restored deduction can recover several hundred dollars at a 22% marginal bracket — but only when total itemized deductions exceed the standard deduction. Workers paying FHA MIP at the standard 0.55% annual rate (HUD Mortgagee Letter 2023-05) on a $300,000 balance will see roughly $1,650 of newly deductible insurance per year fall under this restored category.[19, 24]

Whether the math actually rewards itemizing depends on the comparison with the standard deduction. For tax year 2026 the IRS-published standard deduction sits in the low-$30,000s for married-filing-jointly and the mid-$15,000s for single filers; a typical first-time buyer with a $300,000 mortgage at 6.30% pays roughly $18,800 of interest in year one — below the joint standard deduction even when stacking property tax and other state-and-local levies up to the $10,000 SALT cap. Use IRS Schedule A to compare itemized totals against the standard deduction; IRS Tax Topic 504 covers "discount points" paid at closing — generally fully deductible in the year paid for a primary-residence purchase but amortized over the loan term for refinances. IRS Publication 530 walks first-time owners through the full set of deductible expenses, including real-estate taxes, mortgage insurance, and certain energy-efficiency credits.[27, 26, 25]

When Refinancing Makes Sense

Refinancing replaces your existing mortgage with a new one — typically at a lower rate, shorter term, or to convert from ARM to fixed. The decision is fundamentally a break-even calculation: divide the total closing costs (origination, appraisal, title, escrow, recording, etc.) by the monthly savings to get the months until you recover the cost. If you plan to stay in the home longer than that break-even period, the refinance pencils out. If not, a no-cost refinance with a slightly higher rate may be the better answer.[8]

Closing costs on a refinance typically run 2–5% of the loan amount — on a $300,000 refinance that's $6,000 to $15,000. Lender credits can offset some of these costs in exchange for a slightly higher rate, while paying "discount points" (1 point = 1% of the loan amount) buys down the rate. The CFPB Loan Estimate disclosure puts every line item in the same standardized format across lenders so you can compare apples to apples. If you are refinancing a mortgage that is several years old, remember that resetting to a 30-year term restarts the front-loaded interest curve — even at a lower rate, your total lifetime interest can rise unless you keep the same remaining term or go shorter.[7]

Common Mortgage Mistakes (and How to Avoid Them)

The most common mistake is buying the maximum house the lender qualifies you for rather than the house your budget actually supports. Lenders use front-end DTI (housing payment / gross income) and back-end DTI (all debt / gross income) ratios that often allow housing burdens of 28–43%, but the real-world budget constraint is your after-tax income minus retirement contributions, healthcare, transportation, food, and emergency-fund maintenance. Always sanity-check the lender's pre-approval against your own line-by-line monthly budget.[9]

Another frequent trap is failing to shop multiple lenders. The CFPB found that homebuyers who get loan estimates from at least three lenders save an average of $300 per year in interest costs versus those who accept the first offer — over a 30-year term that compounds to roughly $9,000. Shopping is also how you discover whether the first lender quoted you the best terms or simply the most convenient ones. The Loan Estimate disclosure was specifically designed to make side-by-side comparison easy.[15]

Other classic pitfalls: locking in an ARM teaser rate without stress-testing the worst-case post-reset payment; skipping the home inspection to win a competitive bid (and missing $20,000 of foundation repairs); and using a piggyback HELOC at a high variable rate to avoid PMI without doing the math on which is actually cheaper. The common thread is a refusal to do arithmetic before signing. The calculator above is the entire arithmetic — every advanced toggle, every line of the schedule. Use it as a forcing function for the questions you should be asking your lender, not as a replacement for those conversations.

Key Takeaways

A mortgage is the largest financial transaction most households will ever undertake, and the four levers that drive lifetime cost are loan amount, interest rate, term length, and prepayment behavior. The PMT formula is closed-form and identical across lenders — what differs is the rate you qualify for, the closing-cost stack, and the escrow components layered on top. Use the calculator above to test scenarios before the loan estimate arrives so you walk into the lender's office with a clear floor and ceiling for what you will accept. Run the PITI toggle to see your true monthly burden. Run the PMI toggle if your down payment is under 20% and watch the auto-termination drop off at 78% LTV. Run the extra-payment toggle to see how a small $200 monthly addition can save five-figure interest costs. Then compare against at least three Loan Estimates from different lenders.