Mortgage Payment Calculator

What is a mortgage payment calculator?

A mortgage payment calculator works out your monthly home loan payment from three inputs: the loan amount, the annual interest rate, and the term in years. The calculator above returns your monthly principal and interest (P&I), and then adds optional property tax, home insurance, and HOA dues to estimate your full monthly payment. It also shows the total interest and the total of all payments over the life of the loan.

In short: type your numbers, and you instantly see what the house costs each month and across the whole mortgage, before you ever talk to a lender.

How the mortgage payment is calculated

Monthly principal and interest use the standard amortization formula:

M = P × i × (1 + i)ⁿ ÷ ((1 + i)ⁿ − 1)

where:

• M = monthly principal and interest payment
• P = loan amount (principal), in your currency
• i = monthly interest rate = annual rate ÷ 100 ÷ 12
• n = number of monthly payments = years × 12

If the rate is 0%, the formula simplifies to M = P ÷ n. Once M is known, the rest follows:

• Total of payments = M × n
• Total interest = M × n − P
• Full monthly payment = M + (property tax ÷ 12) + (home insurance ÷ 12) + monthly HOA

The tax, insurance, and HOA add-ons do not change M; they sit on top of it. Lenders call the combined figure PITI (principal, interest, taxes, insurance).

Examples

Example 1 — $300,000 at 6.5% for 30 years

• i = 6.5 ÷ 100 ÷ 12 = 0.00541667, n = 30 × 12 = 360
• (1 + i)ⁿ ≈ 6.99179
• M = 300,000 × 0.00541667 × 6.99179 ÷ (6.99179 − 1) ≈ $1,896.20
• Total of payments = 1,896.20 × 360 ≈ $682,633
• Total interest = 682,633 − 300,000 ≈ $382,633

Add $3,600/yr property tax plus insurance ($3,600 ÷ 12 = $300/month) and the full monthly payment rises by about $300 to roughly $2,196.

Example 2 — $400,000 at 7.0% for 30 years

• i = 7.0 ÷ 100 ÷ 12 ≈ 0.00583333, n = 360
• M ≈ $2,661.21
• Total of payments ≈ $958,036
• Total interest ≈ $558,036

A higher rate and larger loan push total interest well past the amount borrowed.

Example 3 — $250,000 at 5.5% for 15 years

• i = 5.5 ÷ 100 ÷ 12 ≈ 0.00458333, n = 15 × 12 = 180
• M ≈ $2,042.71
• Total of payments ≈ $367,688
• Total interest ≈ $117,688

The shorter term means a higher monthly payment but far less interest than a 30-year loan.

Example 4 — $200,000 at 0% for 30 years

With a 0% rate, M = P ÷ n = 200,000 ÷ 360 ≈ $555.56, total of payments = $200,000, and total interest = $0. This is the simple no-interest case the calculator handles automatically.

Reference table: monthly P&I per $100,000 borrowed

Multiply the figure by your loan size in hundred-thousands. For a $300,000 loan at 6.5%, that is 3 × $632.07 ≈ $1,896.20, matching Example 1.

Annual rate	15-year term	30-year term
4.0%	$739.69	$477.42
5.0%	$790.79	$536.82
6.0%	$843.86	$599.55
6.5%	$871.11	$632.07
7.0%	$898.83	$665.30

Common uses

• Budgeting before house hunting so you shop in a price range you can actually afford each month.
• Comparing loan offers by holding the loan and term fixed and changing only the rate.
• Choosing a term to weigh a lower 30-year payment against the big interest savings of a 15-year loan.
• Estimating PITI by adding tax, insurance, and HOA to see the true monthly cost.
• Refinance checks to compare a new rate against your current payment.

Tips and common mistakes

• Use the loan amount, not the home price. Subtract your down payment first; P is what you actually borrow.
• Enter the annual rate, not a monthly one. The tool divides by 12 internally to get i.
• Property tax and insurance are entered yearly here. The calculator divides them by 12, while HOA is already monthly.
• Do not confuse rate with APR. APR also folds in fees and points, so a lender’s APR can sit above the rate you enter.
• Compare total interest, not just the monthly payment. A low payment often hides a long term and a much larger total cost.

Limitations and notes

This calculator assumes a fixed interest rate, equal monthly payments, and monthly compounding. It does not model PMI, escrow shortfalls, adjustable-rate resets, balloon payments, extra principal payments, or closing costs, and it rounds the term to whole months (years × 12). Tax, insurance, and HOA are treated as constant, though real bills change over time. Treat results as a close estimate; confirm exact figures with your lender or loan officer.

Disclaimer: This tool is for general information and education only and is not financial or lending advice. Your actual payment, APR, and total cost may differ due to fees, taxes, insurance, rounding, and rate changes.

For related planning, try the loan calculator for any amortizing loan, the compound interest calculator to grow savings, or the ROI calculator to gauge an investment, all in Finance.