Garage Conversion Cost Calculator
Converting a 400 square foot double garage runs about $30,113 in Atlanta — $20,714 to $39,511, or $75 a square foot. That is 2.5× cheaper than building an addition of the same size, because the foundation, the walls and the roof already exist. ⚠️ 19% of it is not decoration: it is what a change of use requires — insulating to current code, and an escape window if anyone sleeps there.
Estimate the cost for your home
Estimated cost of converting the garage
$30,593
typical · range $21,177 to $40,008 · 400 sq ft · $76 per sq ft · 185.8 trade hours
Building a floor over the slab raises it three or four inches, and that comes straight off the headroom. Measure the garage before committing: most codes want about seven feet clear in habitable space, and a garage ceiling is often lower than a house ceiling to begin with.
Labour priced at national wages. Enter a ZIP code to price it for your area. 67% of this figure comes from modelled material prices — each line shows its own uncertainty.
Priced from bls.gov Aug 2026how every line is sourced
The one input that changes the answer for you.
Sleepers shimmed to level, insulation between them and a subfloor on top. It fixes the slope, the step down from the house and the cold slab in one go, and it gives somewhere for wiring to run. ⚠️ It also raises the floor by three or four inches, which comes straight off the headroom — worth measuring before choosing, because a converted garage that ends up under seven feet is not a habitable room in most codes.
The simplest case: heated, insulated, finished habitable space with no plumbing and no sleeping. It still needs the insulation, the electrics and the change of use, and it does not need an escape window.
The floor, three ways
| Build a new insulated floor over the slab | $30,593 |
|---|---|
| Level the slab with a self-levelling screed | $28,865 |
| Leave the slab as it is | $26,662 |
⚠️ A garage slab is built wrong for a room on purpose: it falls towards the door so water runs out, and it sits below the house floor so petrol vapour cannot flow in. Both are correct in a garage and both are a problem in a bedroom.
And what you use it for
| A living room, office, gym or playroom | $30,593 |
|---|---|
| A bedroom | $33,281 |
| A bedroom with its own bathroom | $38,075 |
A bedroom adds the escape window. A suite adds the drain — and in a garage a drain means saw-cutting the slab, which is why it costs what it does. The bathroom fit-out itself is priced on our bathroom addition page, not here.
1 / 5
The figure above is already calculated. Each step just makes it more yours, and you can stop at any of them.
Convert this, or build the same room instead
| Convert the garage you have | $30,593 |
|---|---|
| Build a 18 × 22 ft addition instead | $78,686 |
| The addition is | 2.6× as much — $48,093 more |
Both figures come from models on this site at the same BLS wages for your area, on the same square footage — which is the only reason they can be put next to each other. The gap is the whole shell: a garage already has a foundation, four walls and a roof, and an addition has to buy all three before it starts on the room. ⚠️ What the addition buys for that difference is the thing this table cannot price: you still have a garage afterwards. In most American markets a house without one sells to a smaller pool of buyers, and the cars, the bikes and the boxes have to go somewhere. That is a judgement about your street rather than a number, and it is the real comparison.
It is a change of use, not a refit
| Drawings and the change-of-use permit | $1,500 |
|---|---|
| Insulating the walls and the ceiling to current code | $3,024 |
| Insulating the walls and the ceiling to current code — labour | $1,027 |
| Together, out of $30,593 | $5,551 · 18% |
The most searched question about garage conversions is whether you need permission, and the short answer is yes: this is a change of use rather than a repair. That is what brings these lines with it — insulating to the energy code in force where you live, an escape window if anyone is going to sleep in there, and dealing with any gas appliance that stays in the space. ⚠️ Doing it without a permit is cheaper exactly once, and the bill arrives when the house is sold: unpermitted living space cannot be advertised as square footage, an appraiser will not count it, and a buyer’s inspector will write it up. A quote that reads “insulate, board and paint” is a quote for a different job from this one.
| Line item | Qty | Cost | Source |
|---|---|---|---|
| Drawings and the change-of-use permit1 per project | 1each | $600–$2,400 | estimated±60% |
| Stripping out and protecting the rest of the housefloor area × 0.05 hours × lead factor | 20hour | $880–$945 | sourced |
| New insulated floor built over the slabfloor area, when a new floor is built over the slab | 400sq ft | $1,680–$3,600 | estimated±36% |
| New insulated floor built over the slab — labourfloor area × 0.055 hours | 22hour | $1,244–$1,336 | sourced |
| Closing the garage door opening: framing, window and claddingwidth of the garage door opening in linear feet | 16linear ft | $1,520–$4,160 | estimated±46% |
| Closing the garage door opening — labouropening width × 1.35 hours | 21.6hour | $1,221–$1,312 | sourced |
| Insulating the walls and the ceiling to current codewall and ceiling area | 1,080sq ft | $1,728–$4,320 | estimated±43% |
| Insulating the walls and the ceiling to current code — labourwall and ceiling area × 0.02 hours | 21.6hour | $991–$1,064 | sourced |
| Plasterboard, taped and finishedwall and ceiling area | 1,080sq ft | $1,620–$3,240 | estimated±33% |
| Plasterboard, taped and finished — labourwall and ceiling area × 0.032 hours | 34.6hour | $1,901–$2,042 | sourced |
| Flooring, trim and decorationfloor area | 400sq ft | $2,600–$6,800 | estimated±45% |
| Flooring, trim and decoration — labourfloor area × 0.085 hours | 34hour | $1,568–$1,685 | sourced |
| Rewiring it as a room rather than a garagefloor area | 400sq ft | $960–$2,200 | estimated±39% |
| Rewiring it as a room rather than a garage — labourfloor area × 0.05 hours | 20hour | $1,180–$1,268 | sourced |
| Extending the existing heating and cooling in1 when the existing system is extended | 1each | $800–$2,900 | estimated±57% |
| Extending the existing heating and cooling in — labour12 hours when the existing system is extended | 12hour | $684–$735 | sourced |
| Total | $21,177–$40,008 | ±31% |
Where these numbers come from
- Convert, or build the same room instead
- This is the question Google shows alongside the search, and it is answerable properly because both models live here: $30,113 to convert this garage against $76,444 for a 18 × 22 foot addition of the same floor area on our room addition cost calculator — same BLS wages, same metro area, 2.5 times as much. The whole gap is the shell. A garage has a foundation, four walls and a roof; an addition buys all three before it starts on the room. ⚠️ And the addition buys one more thing this table cannot price: you still have a garage. In most American markets a house without one sells to a smaller pool of buyers, and the cars, the bikes and the boxes go somewhere else. That is a judgement about your street rather than a number, and it is the real comparison rather than the arithmetic one.
- The slab is built wrong for a room, on purpose
- A garage floor falls towards the door so that water driven in on a car runs back out, and it usually sits a few inches below the house floor so that petrol vapour cannot flow inwards. Both are correct in a garage. Both are a problem in a bedroom, and fixing them is not a levelling compound, it is a floor: sleepers shimmed to a plane, insulation between them, a subfloor over the lot — $30,113 against $28,476 for a screed and $26,393 for leaving it alone. ⚠️ It also raises the floor three or four inches, which comes straight off your headroom. Measure the garage before choosing: most codes want about seven feet clear in habitable space, and a garage ceiling is often lower than a house ceiling to begin with. A converted garage that ends up under that height is not habitable however well it is finished.
- What the change of use brings with it
- $5,669 of this job — 19% — exists because the space stops being a garage. Insulating the walls and ceiling to the energy code in force where you live is the biggest part of it: DOE Building Energy Codes Program, State Energy Code Methodology (retrieved 2026-08-24) tracks which code each state has adopted, and ENERGY STAR, Insulation Tax Credit (retrieved 2026-08-24) covers the products. Then the escape window if it becomes a bedroom — $32,648 against $30,113 — which is a hole cut through an exterior wall with a lintel over it, and the item that makes bedroom conversions fail inspection when the quote said “board and paint”. ⚠️ And any gas appliance left in the space: combustion appliances in or next to sleeping areas are tightly restricted, and CDC, Carbon Monoxide Poisoning Basics (retrieved 2026-08-24) is why the rule exists rather than a formality.
- A bathroom in there, and where the wages come from
- Turning the space into a suite is $37,058 here against $32,648 for the bedroom alone, and the difference is not the fixtures — it is that a drain in a garage runs inside the concrete. The slab gets saw-cut, broken out, dug, the pipe laid to fall, and then backfilled and re-concreted. ⚠️ The fixtures and the fit-out are not in that number at all: our bathroom addition cost calculator prices those, and adding the two together is the honest total for a suite. In a house built before 1978, stripping out disturbs painted surface and brings the work inside EPA, Lead Renovation, Repair and Painting Program (retrieved 2026-08-24). Wages from BLS OEWS, May 2025, retrieved 2026-08-20, for carpenters, electricians, insulation workers and the rest, benefit-loaded from BLS ECEC. If the garage is staying and the space has to come from somewhere else, our basement finishing cost calculator is usually the next cheapest floor in the house.
- Material prices
- Modelled estimates, not sourced prices. No public, machine-readable source of US residential material prices exists, and we would rather say so than pretend otherwise. Each line carries its own uncertainty band. How we estimate them.
Contractor overhead and profit applied at 33–43% over direct cost. Data last reviewed 2026-08-24.
What this figure does not include
- The permit fee, and whether your area allows it
- ⚠️ Some jurisdictions restrict garage conversions outright, and many require a minimum number of off-street parking spaces to remain. That is a phone call to the building department, it is free, and it should come before any of this.
- Losing the garage
- It is the largest cost on this page and it has no dollar figure: the cars go outside, the storage goes somewhere, and a house without a garage sells to a smaller pool of buyers in most American markets. Whether that matters is a judgement about your street rather than a number we can publish.
- A service upgrade if the panel is full
- The electrical assumes there is room in the existing panel for the new circuits. Where there is not, that is a service upgrade priced on our electrical panel page.
- Bathroom drainage
- Turning the space into a suite means a new drain run and, where the slab sits below the sewer line, a sewage ejector pump. Our bathroom addition calculator prices that properly, and it is a large number on its own rather than a rounding error on this one.
- Damp coming up through the slab
- A garage slab often has no vapour barrier under it, because it never needed one. Building a floor over it assumes the slab is dry. If it is not, that is a moisture problem to solve first — sealing or a proper barrier — rather than something to cover with a subfloor.
- Re-siding or re-roofing to match
- Cladding the infill panel to match is included. Re-cladding a whole elevation because the match is poor is not, and it is priced on our siding page.
Questions people actually ask
Do I need permission to convert my garage?
Almost certainly yes, and the reason matters more than the answer: this is a change of use rather than a repair. That is what brings the current insulation requirements with it, an escape window if anyone will sleep in there, rules about any gas appliance left in the space, and a set of inspections. On this model those code-driven lines come to $5,669, 19% of the job. ⚠️ Some jurisdictions restrict conversions outright, and many require a minimum number of off-street parking spaces to remain — which a converted garage removes. One free phone call to the building department settles both, and it belongs before any of this rather than after. Doing it unpermitted is cheaper exactly once: unpermitted living space cannot be advertised as square footage, an appraiser will not count it, and a buyer's inspector will write it up.
Is it cheaper to convert a garage or to build an addition?
Cheaper, and by a wide margin: $30,113 to convert this garage against $76,444 to build a 18 × 22 foot addition of the same floor area — 2.5 times as much, or $46,331 more. Both figures come from models on this site at the same BLS wages for the same metro area, which is the only reason they can be put side by side. The gap is the entire shell: a garage already has a foundation, four walls and a roof, and an addition has to buy all three before it starts on the room. ⚠️ What the addition buys for that difference is the thing no calculator prices — you still have a garage afterwards. In most American markets a house without one sells to a smaller pool of buyers, and the cars and the boxes have to go somewhere.
Is it expensive to convert a garage into a room?
$30,113 on this model for a 400 square foot double garage in Atlanta — $20,714 to $39,511, or $75 a square foot, which is a fraction of what new construction costs per foot. A single garage of about 240 square feet comes to $20,483. ⚠️ The line that surprises people is the floor. A garage slab falls towards the door so that water runs out, and it usually sits a few inches below the house floor so that petrol vapour cannot flow inwards — both correct in a garage, both a problem in a bedroom. Building a level insulated floor over it is $3,720 more than leaving the slab alone, and it takes three or four inches off your headroom, which is worth measuring before you decide.
What is the cheapest way to do a garage conversion?
Stripped back to the least this model will price — slab left as it is, garage door kept, no heating extended — it is $24,585 against $30,113. ⚠️ And that is a workshop, a gym or storage rather than a room: the floor still slopes to where the door was, it is still a step down from the house, and an uninsulated slab on the ground is cold enough to be the reason nobody uses the space. If it is genuinely going to be habitable, the honest savings are elsewhere: keep it as one open room rather than partitioning it, choose a ductless heat pump instead of extending ducts, and do not make it a bedroom unless you need one — the escape window alone is the difference between $30,113 and $32,648.
Taken from Google’s “people also ask” results for this search on 2026-08-24, not invented.
Other cost calculators
The first of these are the jobs closest to this one — the ones that turn up in the same quote, or instead of it.
- Bathroom addition cost
Prices the drain, the vent and the joist work no quote itemises, and the pump a bathroom below the sewer line cannot do without.
- Basement finishing cost
Prices a dry basement, says what getting it dry first would cost, and works out whether there is still enough headroom once the work is done.
- Bathtub replacement cost
What it costs to swap a bathtub, including the wall that has to come off to get the old one out and the weight that decides the hours.
- The full garage conversion cost dataset
Every unit price, every quantity rule and the reasoning behind each estimate, as a plain table.
- How we calculate
The formula, the sources, and an honest account of which parts of the model are weak.