A 12x24 slab is 288 square feet, which is the classic one-car garage footprint. That detail matters more than the square footage, because a slab that lives under a parked vehicle gets priced differently than a patio of the same size.
The example math first
| Finish | Example rate | 12x24 (288 sq ft) |
|---|---|---|
| Standard broom | $9 / sq ft | $2,592 |
| Colored | $12 / sq ft | $3,456 |
Those are example rates, there to make the math concrete, not to tell you what your market pays. Nearly every garage slab gets the broom finish. The colored row is there for the rare customer who wants the floor to look like something.
Vehicle loads change the pour
A patio carries people and furniture. This slab carries a car or truck rolling over the same two strips of concrete every single day. That is why garage-type slabs get poured thicker than 4 inch flatwork, and why reinforcement earns its keep. At the example add-on rate of $1.50 per square foot, mesh across this slab is $432. The thickness question is worth its own read: see 4 inch vs 6 inch slab.
If the slab will carry walls, the edges matter too. A monolithic pour with thickened edges under the framing is a different forming job than a flat pad, and the quote should say so.
The rest of the add-on math
Tearing out an old cracked slab first, at the example $4 per square foot, adds $1,152. Site prep and grading at the example $2 per square foot adds $576. Stack tear-out, prep, and mesh on the broom example and this “simple” slab moves from $2,592 to $4,752. None of that is padding, it is the actual work.
Sanity-check your own rate
Per-square-foot pricing only works if the rate is really yours. What to charge per square foot for flatwork walks through building the rate from costs, and the concrete slab cost calculator lets you run any other size against the example numbers.
Set your real rates up once in PriceDesk and this whole quote, add-ons included, takes about ten seconds standing in the driveway. The trial is free for 14 days.