Payment calculator
What will it cost per month?
Start with a purchase price to see the monthly payment, or start with the payment you want and work backward to a price. Building a house? Switch to the build option and enter land and construction costs to see the monthly payment on the project. Adjust the assumptions to match your situation.
Based on a national average of 7.38% for 30 years and 7.03% for 15 years as of Oct 21, 2026, from Mortgage News Daily. Your estimate uses 7.505%, which is 0.125 points above that average for your credit range.
What you're doing
Buying an existing home, or building on land you buy or already own.
Your price or payment
Your loan
These set the loan, the rate, and the payment.
Taxes and costs
Defaults are close for Gallatin County. Change them if you know your numbers.
Your income
Optional. Type it in the way you know it and the results will show how this payment compares with the usual 28% guideline.
Nothing entered yet. A rough guess is fine, you can change it any time.
Estimated monthly payment
$4,169/ month
- Loan amount
- $520,000
- Down payment
- $130,000
- Principal and interest
- $3,638
- Property taxes
- $406
- Home insurance
- $125
- Total monthly payment
- $4,169
Comfort check
Type in your income, in any form you know it, to see how this payment compares with the usual 28% guideline and what price to aim for.
See what it buys
Opens a Zillow search for $585,000 to $685,000, 3+ beds, 2+ baths.
Zillow does not officially support pre-filtered links, so glance at the filters once the page opens.
Want a second set of eyes on the numbers, or on building versus buying? That is where the builder side of this helps most.
Talk to BillBozeman affordability, in plain numbers
Buying in the Gallatin Valley comes down to two questions: what a price costs per month, and what price range the payment you want supports. The calculator above answers both. These are the pieces behind the numbers, and the ones worth checking before you make an offer.
How much house can I afford here?
Most lenders start with the 28% guideline, housing at or under 28% of gross monthly income. The comfort check in the calculator applies it to your income and shows the price it points to at today's rates. Approval also weighs existing debts, credit history, and reserves, so treat that price as a planning target, not an approval.
What the monthly payment covers
Along with principal and interest, a Gallatin County payment carries property taxes, homeowners insurance, HOA dues in many subdivisions, and mortgage insurance when the down payment is under 20%. Taxes here follow the assessed value and the local mill levy, which varies by school district. 0.75% of the purchase price a year is a reasonable planning figure, and the actual bill on a specific property can be checked before you make an offer.
Building changes the math
A construction project counts land equity as part of the down payment. Land you already own, or land you buy and pay down, does the same work as cash toward the build. Site work, utilities, permitting, and carrying costs during construction sit outside this estimate, and those are worth pricing before you commit to a lot.
The area moves the number
A short drive in any direction from Bozeman changes lot size, utilities, and price. Properties outside town often run on well and septic, which adds both an upfront cost and ongoing maintenance. Comparing areas and school assignments before you lock in a price range keeps the monthly number honest.
How this works
- Principal and interest come from the standard loan formula, applied to the loan amount, your rate, and the term.
- Rates start at the current national average for 30-year and 15-year fixed loans, then adjust for your credit score range. Lenders price loans with more factors than that, so treat the result as a planning number.
- Property taxes default to 0.75% of the purchase price a year, a reasonable Gallatin County starting point, and you can set your own rate. Insurance and HOA dues are yours to adjust.
- A down payment under 20% adds mortgage insurance at about 0.5% of the loan a year, which is typical for a conventional loan.
- Building instead of buying changes the math. The build option covers land and construction cost, and counts land you already own as the down payment. Site work, utilities, permitting, and carrying costs during the build sit outside it, and that is where a builder's eye helps most.
Estimates only, for planning. Not a loan offer, a rate quote, or a credit decision.