What’s the cost of laying a 20×20 slab?

On average, a 20×20 slab costs $2,468. The cost per square foot is between $4 and $8 on average. However, most homeowners spend on average between $5.35 to $6.17 per square foot for both materials and installation.
The final cost depends on slabs size, thickness, and any special reinforcement, e.g., wire mesh or rebar.