Detached Garage Cost Calculator, Bozeman and Gallatin County
Set the size, the finish level and where the property is, and see the range with permits and the geotechnical report broken out as their own lines.
No obligation. Every estimate starts with a walkthrough of the lot, the access and where the building can actually sit.
Gallatin County, MTCalculator
Price a detached garage
Finish level moves the cost per square foot more than size does. Change it first and watch what happens.
These are planning estimates, not quotes. Every figure comes from published cost bands for the Gallatin Valley in 2026. A calculator cannot see your ground, your access, your utilities or your drawings, and it does not know what a geotechnical report will find. Treat the range as a way to decide whether a project is worth pursuing, not as a price.
Why these numbers
Where these numbers come from
The bands are what a detached garage costs to build in the Gallatin Valley in 2026, including the things a national calculator leaves out: footings to 36 inches, engineered trusses designed to a real snow load, and a slab built for a climate with a Severe weathering classification.
Everything that is process rather than construction is added separately. Inside Bozeman that means the building permit calculated on the city's published formula and the geotechnical report the city requires at application. On county ground inside a zoning district it means a land use permit. On unzoned county ground it means neither.
The result is a number you can take apart. If the permit line surprises you, that is useful information about your parcel rather than a hidden markup.
What is excluded: site grading beyond the building pad, septic work, driveway construction, landscaping, and whatever a geotechnical report turns up. Those are real and we would rather leave them visible as gaps than guess at them.
Ranges reflect what a detached garage costs to build in the Gallatin Valley in 2026, including footings to 36 inches, framing, roofing, siding, overhead doors and normal permit costs. They exclude long utility runs, difficult access, septic work and site grading beyond the building pad. For national context, HomeGuide, 2026 national cost guide for a two-car detached garage puts a two-car detached garage at $20,000 to $57,600 with an average near $38,800. Bozeman sits at the upper half of that range, and a heated shop finish goes past the top of it.
Cost factors
What moves the number most
The biggest single lever
Shell to working shop is a spread of roughly three to one per square foot. Before you argue about size, settle whether the building is heated, because that decides the slab, the envelope and the door.
Thousands, and weeks
Inside Bozeman: permit plus a required geotechnical report. Inside a county zoning district: a land use permit. On unzoned county ground: generally neither. Same building, different process cost.
Can a concrete truck reach it
A mixer needs a route in and firm ground to sit on. Where it cannot get there, concrete is pumped, and pumping is a real line rather than a rounding error.
Next step
Get the range checked against your actual lot
The calculator does not know what your ground does or how far the power has to travel. A walkthrough does, and it costs nothing.
Questions
About these costs
How much is a 24 by 24 detached garage in Bozeman?
Roughly $28,000 to $40,000 as an unheated shell on unzoned county ground, and about $30,000 to $44,000 inside Bozeman city limits once the permit and the required geotechnical report are added.
Insulated and drywalled, the same building runs about $38,000 to $55,000. Finished and heated is higher again.
Why does the calculator ask where the property is?
Because it changes what is required. Inside Bozeman you get a building permit fee plus a mandatory site-specific geotechnical report. Inside a county zoning district you get a land use permit. On unzoned county ground a private garage for your own use is generally exempt from the state building code.
That is a real difference in both money and schedule, so it belongs in the number rather than in a footnote.
Does the price include the overhead door?
One overhead door package and one service door are in the base band. A second overhead door is a separate option, because whether you want one 16 foot door or two 9 foot doors is a genuine choice with a cost attached.
Taller doors are handled in the RV garage calculator, since they change the wall framing as well as the door.
What is not included?
Site grading beyond the building pad, septic work, driveway construction, landscaping, and anything a geotechnical report turns up. Long power runs and a concrete apron are available as options rather than assumptions.
We would rather show you a visible gap than a precise-looking guess.
Can I trust this enough to set a budget?
To decide whether to proceed, yes. To sign a contract, no. The honest use of this tool is to find out in two minutes whether the building you have in mind is anywhere near the money you have in mind.
After that, a site visit and a written scope is what turns it into a price.
Related
Other calculators and pages
Detached garages
What is actually in the build, from footings to the door opener.
Service page →Garage with loft calculator
Add usable space above and see what the deeper footings and the stair cost.
Open calculator →Slabs and concrete
The part of the build that cannot be corrected afterwards.
Service page →Get it real
A range is a start. A walkthrough is the answer.
Send the property address and what you have in mind. The site visit is free and it is where a range becomes a scope.