This Montana Mortgage Calculator estimates your full monthly payment in Montana — not just principal and interest, but the complete PITI: Principal, Interest, Taxes, and Insurance. It bakes in Montana’s 0.74% effective property-tax rate and roughly $2000/yr homeowners insurance so the number reflects what actually leaves your account each month.
How it works
The principal and interest come from the standard amortization 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 number of monthly payments (years times 12). When the rate is 0%, the payment is simply P / n.
On top of principal and interest the tool adds two Montana-specific monthly costs:
- Property tax:
(home value * 0.0074)per year, divided by 12. Montana’s effective rate is 0.74%. - Homeowners insurance: about $2000 per year, divided by 12.
If your down payment is below 20%, the tool also adds PMI at 0.5% per year of the loan balance, divided by 12. At 20% down or more, PMI is dropped.
Example
Take a $400,000 Montana home with $40,000 down (10%), leaving a $360,000 loan at 6.5% over 30 years:
- Principal and interest: about $2,275/month
- Property tax (0.74% of $400,000 / 12): about $247/month
- Insurance ($2000/yr / 12): about $167/month
- PMI (0.5%/yr of the loan, since down is under 20%): about $150/month
That totals roughly $2,839/month in Montana — noticeably above the $2,275 principal-and-interest figure alone.
Notes
This is an estimate for planning only and is not financial or tax advice. It uses Montana’s average effective property-tax rate of 0.74%; your actual county or municipal rate, insurance premium, HOA dues, and PMI rate will vary. Verify your property tax with the Montana Department of Revenue or your local assessor, and confirm all loan figures with your lender.