Reference-first • Calculator-backed • Field-practical
Concrete slab thickness & rebar guidance that answers the question fast.
Use the calculators, tables, and application guides below to choose a practical starting point for slab thickness, PSI, and reinforcement. For engineered design, unusual loads, or poor soils, consult a licensed professional.
Slab Thickness Calculator
Rebar Size & Spacing
Volume Calculator
Tables for common applications
Quick rule of thumb: 4" is common for patios/sidewalks; 4.5–6" for light vehicle slabs; 6"+ for heavier vehicles/shops. Rebar helps control cracking but does not replace proper base, joints, and drainage.
This site is educational reference. Local code, soil/subgrade, base thickness, reinforcement detailing, and joint layout can change requirements.
Tables that rank
Filterable, scan-friendly tables that answer “how thick should it be?” for common slabs-on-grade.
Rebar reference
Bar sizes, spacing starting points, and placement guidance for crack control and load distribution.
Foundations that matter
Thickness is only one input. Base, joints, drainage, and curing often decide performance.