How to Calculate Mortgage Payments (2026 Guide)
Buying a home is likely the largest financial decision you'll ever make. Understanding exactly how your monthly payment is calculated—and where every dollar goes—is the first step toward financial security. This guide breaks down the standard mortgage formula, the four main components of a payment (PITI), and how to use them to budget for your dream home in 2026.
What is PITI? The 4 components of a mortgage payment
Most people think of a mortgage payment as just paying back the bank. In reality, your monthly bill usually includes four distinct parts, often referred to by the acronym PITI:
- Principal: The amount that goes directly toward paying down your loan balance.
- Interest: The cost of borrowing the money, paid to the lender.
- Taxes: Your annual property taxes, divided into 12 monthly installments.
- Insurance: Your homeowners insurance premium (and PMI, if applicable).
The Mathematical Formula
The core of your mortgage—the Principal and Interest (P&I)—is calculated using the standard amortization formula:
Where:
M = Total monthly P&I payment
P = Principal loan amount
i = Monthly interest rate (Annual Rate / 12)
n = Number of months (e.g., 360 for a 30-year loan)
A Worked Example (2026 Rates)
Let's say you're buying a $500,000 home with a 20% down payment ($100,000), leaving a $400,000 loan. At a 2026 average rate of 6.85% for a 30-year fixed term:
- Principal & Interest: Using the formula above, your base payment is $2,621.14.
- Property Tax: At a national average of 1.1%, that's $5,500/year or $458.33/month.
- Insurance: Estimating $1,500/year for homeowners insurance is $125.00/month.
- Total Monthly Payment: $2,621.14 + $458.33 + $125.00 = $3,204.47.
Don't forget Private Mortgage Insurance (PMI)
If your down payment is less than 20%, lenders usually require PMI. This protects them if you default. In 2026, PMI typically costs between 0.5% and 1.5% of the loan amount annually. On a $400,000 loan, a 1% PMI rate adds $333.33 to your monthly bill until you reach 20% equity.
How to lower your monthly payment
If the calculated number is too high for your budget, you have three main levers:
- Increase your down payment: Lowering the principal amount (P) reduces both the interest and the base payment.
- Shop for a better rate: Even a 0.5% difference in interest rate (i) can save you hundreds per month and tens of thousands over the life of the loan.
- Extend the term: While a 15-year mortgage saves more in interest, a 30-year mortgage offers a lower monthly payment by spreading the principal over more months (n).