Free Mortgage Calculator

Monthly payment with taxes & PMI, affordability by income, extra payment savings, 15 vs 30 year comparison, and full amortization — formula shown for every result.

How to Calculate Your Mortgage Payment

Use the calculator below or follow these steps to work it out manually. The formula takes under 30 seconds once you have your numbers.

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Home price & down paymentSubtract your down payment from the home price. That's your loan amount (principal P).
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Monthly rate & paymentsDivide your annual interest rate by 12 for monthly rate r. Multiply loan years by 12 for total payments n.
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Apply the formulaM = P × [r(1+r)^n] ÷ [(1+r)^n − 1]. For a $300k loan at 7% for 30 yrs: M = $1,996/mo.
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Add taxes, insurance & PMIAdd monthly property tax + homeowner's insurance + HOA. If down payment < 20%, add PMI (~0.5%/yr ÷ 12).
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≈ 20% of home price
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Optional Costs
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Uses the 28/36 rule: mortgage payment ≤ 28% of gross income, total debt ≤ 36%. Enter your income and existing monthly debts to see how much house you can afford.

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Car, student loans, credit cards, etc.
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Estimate: 1.2% of home price ÷ 12

See how much interest you save and how many years you cut by making extra payments each month.

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Compare total cost, monthly payment, and interest paid between a 15-year and 30-year mortgage on the same loan.

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Full payment-by-payment schedule showing how much goes to principal vs. interest each month and your remaining balance.

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Mortgage Payment Formula
Principal & Interest
M = P × r(1+r)^n
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(1+r)^n − 1
P = loan amount  |  r = monthly rate (annual ÷ 12)
n = total payments (years × 12)

Example: $320k @ 7%, 30 yr
r = 0.07 ÷ 12 = 0.005833
n = 30 × 12 = 360
M = $320,000 × [0.005833 × (1.005833)^360] / [(1.005833)^360 − 1]
M = $2,129/month

How Mortgage Payments Are Calculated

Your monthly P&I payment is fixed for the life of the loan — but the split between principal and interest changes every single month. In the early years, the majority goes to interest.

On a 30-year $320,000 loan at 7%, you pay $2,129/month. In month 1, only $262 reduces your balance — the other $1,867 is interest. By year 25, the split reverses.

This is why extra payments early in the loan are so powerful: they directly reduce the principal, cutting every future interest charge calculated against it.

The 80% equity milestone matters. When your loan balance falls below 80% of your original home value, PMI is automatically cancelled under the Homeowners Protection Act — saving you hundreds per year. Our calculator shows the exact month.
The 28/36 Affordability Rule
28%
Front-End Ratio
Max mortgage payment (PITI) as % of gross monthly income
36%
Back-End Ratio
Max total monthly debt (mortgage + all other debts) as % of income
On $90k/yr income: max mortgage ≈ $2,100/mo  |  max total debt ≈ $2,700/mo

How Much House Can I Afford?

The 28/36 rule is the standard lenders use to evaluate your mortgage application. It's also the most practical DIY affordability check before you start house shopping.

  • 28% front-end ratio: Your total monthly housing payment (mortgage principal, interest, taxes, insurance, PMI, and HOA) should not exceed 28% of your gross monthly income.
  • 36% back-end ratio: Your mortgage plus all other monthly debt obligations (car loans, student loans, credit card minimums) should not exceed 36% of gross income.
  • Down payment impact: A larger down payment reduces your loan amount, eliminates PMI faster, and improves your debt-to-income ratios — each of which can qualify you for a better rate.

Use the Affordability tab above to see three scenarios (conservative, moderate, aggressive) based on your specific income, debts, and down payment.

15-Year vs. 30-Year Mortgage — Which Is Better?

There is no universal right answer. It depends on your cash flow, risk tolerance, and investment alternatives.

30-Year: Lower monthly payment
On a $320k loan at 7%, a 30-year payment is $2,129/mo vs. $2,871/mo for 15 years — $742/month lower. That flexibility is real.
15-Year: Massive interest savings
Same loan: 30-year costs $445,040 in total interest. 15-year costs $196,780. That's a $248,260 difference — equivalent to another home.
15-Year: Better rate offered
Lenders typically charge 0.5%–0.75% less for 15-year mortgages due to lower default risk. That rate discount compounds the savings significantly.
30-Year + Invest the difference
If you invest the $742/mo difference at 8% annual return, you'd have ~$1M in 30 years — likely outpacing the interest savings of the 15-year. This is the case for the 30-year.

Frequently Asked Questions About Mortgages

Honest answers to the most common mortgage questions.

The principal and interest (P&I) formula is 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. Your full monthly payment also includes property tax, homeowner's insurance, HOA fees, and PMI if your down payment was less than 20%.
PMI (Private Mortgage Insurance) protects the lender if you default. It's required when your down payment is below 20%. It typically costs 0.2%–1.5% of the loan annually (~0.5% is average). Under the Homeowners Protection Act (HPA), your lender must automatically cancel PMI when your loan balance reaches 80% of the original home value. Our calculator shows you the exact month this occurs.
On an $80,000 salary, gross monthly income is about $6,667. Using the 28% front-end rule, your max total housing payment is $1,867/month. After subtracting estimated taxes ($400), insurance ($100), and PMI ($100), your max P&I is ~$1,267. At 7% for 30 years, that supports a loan of about $190,000 — so with a 10% down payment you could afford a home around $211,000. Use the Affordability tab for your exact numbers.
With a 10% down payment ($30,000), your loan is $270,000. At 7% for 30 years, P&I = $1,797/month. Adding estimated property tax ($300/mo), insurance ($100/mo), and PMI (~$112/mo), total monthly payment ≈ $2,309. At a 20% down ($60,000), no PMI, loan = $240,000, P&I = $1,597/month, total ≈ $1,997.
With a 20% down payment ($80,000), your loan is $320,000. At 7% for 30 years, P&I = $2,129/month. Adding property tax ($400/mo) and insurance ($133/mo), total ≈ $2,662. At 15 years, P&I jumps to $2,871 but total interest paid drops from $446,473 to $196,782 — a $249,691 saving.
Extra payments go directly toward principal, which reduces the balance on which future interest is charged. On a $320,000 loan at 7%, paying an extra $200/month saves over $62,000 in interest and cuts 5 years off the loan. The earlier you make extra payments, the greater the compounding effect. Use the Extra Payments tab to calculate your exact scenario.
One mortgage point costs 1% of the loan and typically reduces the rate by 0.25%. The break-even calculation: divide the upfront cost by the monthly savings to find how many months until you recoup the cost. On a $320,000 loan, one point = $3,200 and saves ~$53/month — break-even is 60 months (5 years). Only worthwhile if you plan to keep the home longer than the break-even period.

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How Mortgage Payments Work
Deep dive into PITI, amortization, PMI, and strategies to pay off your mortgage years early.
How we keep this accurate: Mortgage payment calculations follow the standard amortization formula used by US lenders. Affordability thresholds (28/36 rule) are based on guidelines from the Consumer Financial Protection Bureau (CFPB). PMI cancellation rules follow the Homeowners Protection Act. State property tax rates are sourced from Tax-Rates.org averages as of 2025. This tool is for informational purposes only and is not financial advice — consult a licensed mortgage professional for your specific situation. Last reviewed May 2026. About CalcMeter →