Garage conversion cost: a one-, two- or three-car garage into a room, every line stated, by state
A two-car garage, 20 by 20 ft: about $12,100 to $15,200, typically $13,300. That's the garage door taken off and the opening framed, sided and fitted with a window, the walls and ceiling insulated and drywalled, the walls painted, a vinyl plank floor and new outlets, plus the contractor's overhead, profit and sales tax. Heating and cooling, plumbing, raising the floor and permits are extra.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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What it costs
| Job | Cost |
|---|---|
| A one-car garage, 12 by 20 ft | $8,700 to $10,900 |
| A two-car garage, 20 by 20 ft | $12,100 to $15,200 |
| A three-car garage, 30 by 20 ft | $17,100 to $21,250 |
Totals include the contractor's overhead and profit (20%) and the state's average sales tax. Prices as of November 2026.
What’s in these numbers
Each total is a typical job, priced the way a contractor’s estimate is priced:
| One-car, 12 by 20 ft | Two-car, 20 by 20 ft | Three-car, 30 by 20 ft | |
|---|---|---|---|
| Garage doors | 9 by 7 door taken off | 16 by 7 door taken off | A 16 by 7 and a 9 by 7 taken off |
| The openings | Framed in, house wrap and vinyl siding outside | Same | Same |
| Windows | One, in the new wall | One | Two |
| Walls | Insulated with R13 batts, drywalled, painted | Same | Same |
| Ceiling | R30 batts and drywall | Same | Same |
| Floor | Vinyl plank over the slab | Same | Same |
| Outlets | Four, with their wiring | Six | Eight |
On top of the work:
- Overhead and profit: 20%, the standard markup on a contractor’s estimate.
- Sales tax on the materials, at the state’s average rate.
Not in them: heating and cooling, plumbing, raising or leveling the floor, a footing under the new wall, ceiling paint, trim, an entry door, and permits.
Before converting
- Permits and zoning. Turning a garage into living space is work the building department reviews, and zoning can have its own rules, such as parking. Ask before the work starts.
- Heat. Where the winter design temperature is below 60°F, the code calls for heating that keeps habitable rooms at 68°F, and portable space heaters don’t count (IRC R303.10). Ducts run from the house’s system, or a ductless unit goes in.
- Bedrooms. Every sleeping room needs at least one emergency escape and rescue opening, such as a window big enough to climb out of (IRC R310.1).
- The house wall. While any part is still a garage, the code keeps it separated from the house, with at least 1/2 inch gypsum board on the garage side (IRC R302.6), and no opening from the garage straight into a sleeping room (R302.5.1).
What moves the price
- Size. A two-car garage has more wall, ceiling and floor.
- The floor. A garage slab can slope toward the door; leveling or raising the floor adds work.
- Heat and air, plumbing. A ductless unit, a run of ductwork, or a bathroom add lines of their own.
- Where you live. Pick your state in the box above.
Common questions
How much does it cost to convert a one-car garage?
About $8,700 to $10,900 for a 12 by 20 garage with the scope above, typically $9,600.
How much is a two-car garage conversion?
About $12,100 to $15,200 for a 20 by 20 garage, typically $13,300.
How much is a three-car garage conversion?
About $17,100 to $21,250 for a 30 by 20 garage with two doors walled in.
What about a basement instead?
The basement finishing cost guide prices framing, insulation, drywall, floor and outlets for three basement sizes.