Mortgage Calculator
Estimate your monthly mortgage payment and total interest from loan amount, rate, and term. Free.
How to use this tool
- Enter loan amount, annual interest rate, term, what do you want to find? and monthly budget (affordability mode) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your monthly payment and the full breakdown beneath it.
Estimate your monthly mortgage payment, total interest, and total cost over the life of the loan. Enter your loan amount, interest rate, and term.
Related data study: What $2,000/month buys at every mortgage rate, computed with this calculator's own amortization engine.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Monthly payment M = P × r(1 + r)n ÷ [(1 + r)n − 1]
Where P = loan principal, r = monthly interest rate (annual rate ÷ 12 ÷ 100), n = total number of monthly payments (years × 12).
Total interest = (M × n) − P. Total paid = M × n.
How it works
This calculator applies the standard amortisation formula to find the fixed monthly payment that fully repays the loan over the chosen term, with each payment covering both interest accrued that month and a portion of the remaining principal.
When the annual interest rate is zero the formula simplifies to principal divided by the number of months. Results assume a fixed interest rate, monthly compounding, and equal payments throughout the term; they do not include property taxes, insurance, or PMI.
Worked example
- Inputs: $300,000 loan, 6.5% annual rate, 30-year term.
- Compute monthly rate: r = 6.5 ÷ 100 ÷ 12 = 0.005417.
- Compute number of payments: n = 30 × 12 = 360.
- Apply amortisation formula: M = 300,000 × 0.005417 × (1.005417)^360 ÷ [(1.005417)^360 − 1] ≈ $1,896.20.
- Total paid = 1,896.20 × 360 = $682,633.47; Total interest = $682,633.47 − $300,000 = $382,633.47.
Monthly payment = $1,896.20 | Total interest = $382,633.47 | Total paid = $682,633.47
Common mistakes to avoid
- Using the annual interest rate directly as r instead of dividing by 12 -- a 6% annual rate means r = 0.06 / 12 = 0.005 per month.
- Setting n in years rather than total months -- a 30-year mortgage means n = 360, not 30.
- Ignoring property tax, homeowner's insurance, and PMI, which can add hundreds of dollars to the actual monthly outlay beyond the principal-and-interest payment this formula produces.
Key terms
- Principal
- The original amount of money borrowed, before any interest is added.
- Amortisation
- The process of paying off a loan in equal periodic instalments that cover both interest and principal, gradually reducing the balance to zero.
- Monthly interest rate
- The annual interest rate divided by 12, applied each month to the outstanding loan balance.
- Term
- The total length of the loan in years (or months), after which the balance must be fully repaid.
- Total interest
- The cumulative extra amount paid above the original principal over the life of the loan.
Frequently asked questions
- How is a monthly mortgage payment calculated?
- Using the amortization formula: P × r(1+r)^n / ((1+r)^n − 1), where r is the monthly rate and n is the number of months.
- Does this include taxes and insurance?
- No — this estimates principal and interest only. Add property tax, insurance, and PMI separately.