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Mortgage Calculator

Estimate your monthly mortgage payment, taxes, insurance, PMI, and full payoff schedule. Plan your home loan with confidence.

Mortgage Advisor ReviewedTrusted by Home Buyers WorldwideCFPB · FHA · Freddie Mac Sourced
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Reviewed By

Michael Chen, CMA — Certified Mortgage Advisor

Last reviewed: May 11, 2026Last updated: May 11, 2026

Mortgage formulas, PMI rules, amortization math, and recommendations on this page are cross-checked against guidance from the Consumer Financial Protection Bureau (CFPB), FHA, Freddie Mac, Fannie Mae, and the Federal Reserve. Read our full Editorial Policy.

Mortgage Calculator

Estimate your monthly home loan payments with our advanced Mortgage Calculator. This tool computes your monthly principal and interest, full amortization schedule, and total loan cost based on your loan amount, interest rate, and loan term.

Whether you're planning to buy a house, comparing 15-year vs 30-year loans, or modeling extra payments to pay off your loan early, this calculator gives you a clear financial picture before making a decision.

What is a Mortgage?

A mortgage is a loan you take out to buy a home or real estate property. The property itself serves as collateral, meaning the lender can claim it if you fail to repay. Most home mortgages are fixed-rate loans — your interest rate stays the same throughout the loan term, so your monthly principal and interest payment never changes.

Each monthly payment covers two parts: principal (the amount that reduces your loan balance) and interest (the cost of borrowing). In the early years, most of your payment goes toward interest. Over time, the balance shifts until most goes toward principal — this is called amortization.

How Mortgage Payments Are Calculated

The standard formula for a fixed-rate mortgage monthly payment is:

M=P×
r(1 + r)n
(1 + r)n− 1

M = Monthly payment

P = Loan principal (home price minus down payment)

r = Monthly interest rate (annual rate ÷ 12)

n = Total number of payments (loan term in years × 12)

Worked Example

Home Price$300,000
Down Payment (20%)$60,000
Loan Amount$240,000
Interest Rate6.5% per year
Monthly Rate (r)0.065 ÷ 12 = 0.005417
Loan Term30 years (360 months)
Monthly P&I Payment≈ $1,514/mo

What Affects Your Mortgage Payment?

Interest Rate

The single biggest lever. A 1% difference on a $300k loan can add or save over $50,000 in total interest over 30 years.

Loan Term

A 15-year mortgage has higher monthly payments but builds equity faster and costs far less in total interest.

Down Payment

Larger down payment = smaller loan = lower payment and no PMI (required if down payment < 20%).

Property Taxes

Typically 0.5–2.5% of home value per year, collected monthly as part of your escrow payment.

Tips to Reduce Your Mortgage Cost

  1. 1Make a larger down payment to reduce your loan principal and potentially eliminate PMI.
  2. 2Choose a 15 or 20-year term — you pay more monthly, but the total interest is dramatically lower.
  3. 3Improve your credit score before applying. Better credit = better rates = thousands saved.
  4. 4Make extra monthly payments. Even $100/month extra can cut years off your mortgage.
  5. 5Refinance when interest rates drop significantly (typically when rates fall 0.75–1% below your current rate).

Key Components of a Mortgage

1

Loan Amount

The total money you borrow after subtracting your down payment.

2

Down Payment

The upfront amount you pay. Higher down payment = lower loan burden.

3

Interest Rate

The cost of borrowing, usually expressed annually (APR).

4

Loan Term

The duration of the loan — typically 15, 20, or 30 years.

Additional Costs to Consider

🔄 Recurring Costs

  • Property taxes
  • Home insurance
  • Maintenance costs
  • HOA fees (if applicable)

1️⃣ One-Time Costs

  • Closing costs
  • Legal fees
  • Property registration
  • Renovation expenses

Final Thoughts

Buying a house is one of the biggest financial decisions of your life. A mortgage calculator helps you understand the real cost — not just the monthly payment, but the total long-term commitment. Use it before every major step: pre-qualification, offers, refinancing, or paying down early.

How Much House Can I Afford?

Most US lenders qualify borrowers using the 28/36 rule: your monthly housing payment (PITI) should not exceed 28% of gross monthly income, and your total monthly debt payments should not exceed 36%. This is the same framework used by Fannie Mae, Freddie Mac, and most mortgage underwriters.

Annual Income (gross)Max Housing (28%)Max Total Debt (36%)
$50,000$1,167/mo$1,500/mo
$75,000$1,750/mo$2,250/mo
$100,000$2,333/mo$3,000/mo
$150,000$3,500/mo$4,500/mo
$200,000$4,667/mo$6,000/mo

Debt-to-Income (DTI) ratio is your total monthly debt payments divided by your gross monthly income. Most conventional lenders prefer DTI ≤ 43%; FHA allows up to 50% with compensating factors. Lower DTI = better rates and easier approval. Use our Loan Calculator to model existing car or student loan payments alongside your mortgage.

15-Year vs 30-Year Mortgage

The most common decision in residential lending. Here's how the two stack up on a $400,000 loan at 7% APR:

Factor15-Year30-YearWinner
Monthly P&I$3,595$2,66130-year (cash flow)
Total Interest$247,200$558,03615-year (saves $310K)
Total Cost$647,200$958,03615-year
Equity GrowthFast (50% by Yr 7)Slow (50% by Yr 18)15-year
Interest Rate~0.50–0.75% lowerHigher15-year
Best ForHigh-earners, fast-equityLower payment flexibilityDepends on goals

Bottom line: a 15-year saves $310K+ in interest but demands 35% more cash flow each month. Many financial planners recommend taking the 30-year (for flexibility) and making the equivalent 15-year payment as an extra principal contribution — best of both worlds if you have the discipline.

Mortgage Payment Breakdown (PITI)

Your total monthly housing payment is called PITI. Some lenders include HOA dues; most don't. Here's what each piece means:

P

Principal

The portion of each payment that reduces your loan balance. Early in the loan: small. Late in the loan: large.

I

Interest

The lender's fee for the loan. Calculated on the remaining balance each month. Highest at the start of the loan and falls every payment as the principal shrinks.

T

Taxes

Property taxes paid to your county/municipality. Typically 0.5–2.5% of home value per year, divided by 12. Held in escrow by most lenders.

I

Insurance

Homeowner's insurance protecting against fire, theft, weather damage, and liability. Typically $1,000–$3,000/year, paid monthly via escrow.

Beyond PITI: two additional costs often appear on the monthly bill. PMI (Private Mortgage Insurance) is required when your down payment is under 20% and protects the lender if you default — typically 0.3–1.5% of the loan amount per year. HOA fees apply in condos and planned communities, ranging from $50 to over $1,000/month, and are not technically part of the mortgage but always factor into affordability.

How Extra Payments Save You Thousands

Every dollar paid above your scheduled principal saves you future interest. Here's the math on a $400,000 30-year loan at 7% (baseline P&I: $2,661/mo):

Extra PaymentYears SavedInterest SavedNew Term
$0 (baseline)0$030 yrs
$50 / month~2.4 yrs~$48,000~27.6 yrs
$100 / month~4.0 yrs~$89,000~26.0 yrs
$200 / month~7.0 yrs~$155,000~23.0 yrs
$300 / month~9.4 yrs~$203,000~20.6 yrs
$500 / month~13.0 yrs~$274,000~17.0 yrs

Pro tip: use the Extra Monthly Payment input above to model your exact savings. Two popular acceleration strategies: (1) bi-weekly payments — make half your monthly payment every 2 weeks (26 half = 13 full payments/yr, equivalent to 1 extra/year, ~4 years saved). (2) round up — if your P&I is $2,661, pay $2,800 and apply $139 to principal. Compounded over decades, both add up.

Fixed-Rate vs Adjustable-Rate (ARM) Mortgage

A fixed-rate mortgage locks your interest rate for the entire loan — the safest option, dominant in the US market. An ARM starts with a lower fixed period (typically 5, 7, or 10 years) then adjusts annually based on a benchmark index (SOFR, Treasury) plus a margin.

FactorFixed-RateARM (5/1, 7/1, 10/1)
Rate stabilitySame rate for entire termFixed for 5/7/10 yrs, then adjusts yearly
Initial rateHigherLower (typically 0.5–1% below fixed)
Payment riskNone — payment never changesCan rise significantly after initial period
Caps on adjustmentsN/ATypically 2/2/5 (annual / period / lifetime)
Best forLong-term buyers (7+ years)Short-term buyers, expecting rate drop, or planning to refinance
US market share~90% of originations~10% of originations

Verdict: stick with a fixed-rate mortgage unless you have a clear, near-term exit (selling, refinancing, or job relocation expected within the ARM's fixed period). The 2008 financial crisis was partly fueled by borrowers who couldn't afford ARM payment resets — the same risk exists today. If you do choose an ARM, fully understand the index, margin, and caps before signing.

Frequently Asked Questions

Your principal & interest payment uses the formula M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (years × 12). Add property tax, insurance, PMI, and HOA to reach your full PITI payment.

Most lenders follow the 28/36 rule: your mortgage payment should be no more than 28% of gross monthly income, and total debt payments (including the mortgage) should not exceed 36%. On a $100,000 annual income, that's about $2,333 max housing payment and $3,000 max total debt — the ceiling most lenders use for qualification.

20% down is the gold standard — it avoids PMI, lowers your monthly payment, and shows lenders financial strength. Conventional loans allow 3–5% down with PMI. FHA loans allow 3.5%, VA and USDA loans can require 0%. Higher down payments mean lower monthly costs and faster equity, but tying up too much cash can hurt liquidity.

Conventional loans typically require a 620+ FICO score; the best rates go to borrowers with 740+. FHA loans accept scores as low as 580 with 3.5% down (500 with 10% down). VA loans typically need 580–620. Each 20-point credit score increase above 620 can lower your rate by 0.1–0.25 percentage points — meaningful over 30 years.

The 28/36 rule is a lending guideline used by most US mortgage underwriters. Your housing payment (PITI) should not exceed 28% of your gross monthly income, and your total monthly debt payments (housing + credit cards + student loans + car loans) should not exceed 36%. Lenders use it as a baseline for what you can responsibly afford.

Private Mortgage Insurance (PMI) is required by most lenders when your down payment is less than 20%. It protects the lender if you default. Once your loan-to-value ratio reaches 80% (you have 20% equity through payments or home appreciation), you can request PMI removal in writing. At 78% LTV, lenders are legally required to remove it automatically.

A 30-year mortgage has lower monthly payments but costs roughly 2× the total interest of a 15-year. On a $400,000 loan at 7%, a 30-year is $2,661/mo with $558K total interest; a 15-year is $3,595/mo with $247K total interest — saving $311K. Choose 15 if you can afford the higher payment and want fast equity; 30 if cash flow matters more.

A fixed-rate mortgage locks your interest rate for the entire loan — predictable payments, ideal if you plan to stay 7+ years or expect rates to rise. An ARM starts with a lower fixed rate (typically 5, 7, or 10 years) then adjusts annually. ARMs can save money if you sell or refinance before the fixed period ends, but carry payment-shock risk.

An extra $100/month on a $400,000 30-year loan at 7% saves about $89,000 in interest and shortens the loan by ~4 years. An extra $200/month saves ~$155,000 and ~7 years. Apply extras specifically to principal — and confirm there's no prepayment penalty (most US mortgages have none). Bi-weekly payments are another popular acceleration trick.

Yes. Most US mortgages have no prepayment penalty (verify in your loan docs). Methods: extra principal payments each month, bi-weekly payments (26 half-payments = 13 full payments per year = 1 extra annually), lump-sum prepayments after a bonus or windfall, or refinancing to a shorter term. Each approach shortens the loan and reduces total interest paid.

An escrow account is a lender-managed account that collects monthly portions of your property taxes and home insurance alongside your mortgage payment, then pays them on your behalf when due. Most US mortgages with less than 20% down require escrow. The benefit: you avoid surprise lump-sum tax bills; the drawback: the lender holds 2–6 months of cushion.

The interest rate is the cost of borrowing expressed as a percentage. APR (Annual Percentage Rate) includes the interest rate plus most fees rolled into the loan — origination fees, mortgage broker fees, points, and some closing costs. APR is always higher than the interest rate and is the better number for comparing loans across lenders.

Refinancing typically makes sense when rates drop 0.5–1.0% below your current rate AND you plan to stay long enough to recoup closing costs. The break-even formula: total closing costs ÷ monthly savings = months to break even. If you'll stay longer than that, refinancing pays off. Closing costs are usually 2–6% of the loan.

HOA dues are usually not included in your principal-and-interest mortgage payment, but most lenders factor them into your debt-to-income calculation for qualification. Some lenders bundle HOA into escrow alongside taxes and insurance. Always include HOA when comparing total monthly housing cost — it can range from $50 to over $1,000 per month.

Most conventional lenders prefer a back-end DTI (total monthly debt ÷ gross monthly income) below 43%, with 36% the comfort threshold. FHA loans allow up to 50% in some cases. Front-end DTI (just housing) should typically stay at or below 28%. Higher DTIs require compensating factors like a large down payment, high reserves, or excellent credit.

Authors & Financial Review

Written By

SamCalculator Editorial Team

Personal finance writers and analysts producing evidence-based mortgage, loan, and investment content sourced from CFPB, Federal Reserve, FHA, Freddie Mac, Fannie Mae, and peer-reviewed research. Read more on our About page.

Reviewed By

Michael Chen, CMA

Certified Mortgage Advisor with 12+ years of residential lending and home-buyer advisory experience. Reviews mortgage formulas, PMI rules, and amortization content on this page for accuracy and compliance with US lending standards.

Last reviewed: May 11, 2026 · Last updated: May 11, 2026

Trusted Sources & References

  1. Consumer Financial Protection Bureau (CFPB) — Owning a Home guide.
  2. U.S. Department of Housing and Urban Development (HUD) / FHA — Home Loan programs.
  3. Freddie Mac — Primary Mortgage Market Survey (PMMS) historical rates.
  4. Fannie Mae — Research and economic insights.
  5. Federal Reserve — Monetary policy and mortgage rate context.
  6. CFPB — Private Mortgage Insurance (PMI) explained.
  7. CFPB — Fixed-rate vs Adjustable-rate Mortgages.

Financial Disclaimer: This mortgage calculator is provided for educational and informational purposes only and is not financial, lending, legal, or tax advice. Estimates do not reflect actual loan offers — real APRs, PMI rates, property taxes, and closing costs vary by lender, location, and credit profile. Before applying for a mortgage, refinancing, or making any home-buying decision, consult a licensed mortgage loan officer, fiduciary financial advisor, or housing counselor. SamCalculator does not originate mortgages, sell financial products, or receive commissions from lenders.

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