A 16x20 slab runs 320 square feet. This is the oversized single garage, and just as often the backyard workshop pad. The four extra feet of width over a 12-foot bay is exactly the difference between parking a vehicle and actually working next to one, which is why this size gets ordered so often.
What moves a shop slab off the base rate
Start with thickness. A shop floor that carries a truck, a trailer, or a standing machine wants more than 4 inch patio thinking. Thicker slab means more concrete per square foot, so the rate has to follow. The trade-offs are laid out in 4 inch vs 6 inch slab.
Then the add-ons, each per square foot on all 320 of them at the example rates:
- Tear-out of an old slab at $4 adds $1,280.
- Site prep and grading at $2 adds $640.
- Rebar or mesh at $1.50 adds $480, and under machinery it is the last place to save money.
One more shop-specific point: if equipment gets bolted down or a compressor lives in one corner, know that before the pour, not after. Moving a slab penetration later is miserable.
The example math
| Finish | Example rate | 16x20 (320 sq ft) |
|---|---|---|
| Standard broom | $9 / sq ft | $2,880 |
| Colored | $12 / sq ft | $3,840 |
These are example rates, not quotes and not market data. Almost every workshop floor gets the broom finish; the colored row is mostly there to show how much the finish choice swings a number this size, $960 on the same footprint.
Stack the common add-ons on the broom example (tear-out, prep, mesh) and 320 square feet goes from $2,880 to $5,280. That is why two bids on “the same slab” can sit thousands apart, and why an itemized quote wins the argument.
Build the rate, then reuse it
If you are still working out what your own number should be, how to price a concrete slab walks through building the rate from mix cost, labor, and overhead. For any other footprint, the concrete slab cost calculator takes whatever length and width the customer throws at you.
Once your real rates are loaded into PriceDesk, a 16x20 with three add-ons is a ten-second quote from the truck. Free for 14 days, no card required.