Rebar Calculator

Rebar (reinforcement bar) is steel bar used to strengthen concrete. Concrete is strong in compression but weak in tension, so rebar is added to provide tensile strength. This combination creates reinforced concrete, which can withstand various forces and is used in most modern construction.

Typical rebar spacing in concrete slabs ranges from 150mm to 300mm (6-12 inches). The exact spacing depends on the slab’s purpose, load requirements, and local building codes. Residential slabs often use 200-250mm (8-10 inch) spacing, while commercial or heavy-duty slabs may require closer spacing.

Bar size determines the cross-sectional area of steel in the concrete, which directly affects the tensile strength of the reinforced concrete. Larger bars provide more strength but are heavier and more expensive. The appropriate size depends on the structural requirements, span lengths, and expected loads on the slab.

Edge cover is the distance from the edge of the concrete to the nearest rebar. It protects the rebar from corrosion and fire. Typical edge cover ranges from 25mm to 75mm (1-3 inches), depending on environmental conditions and structural requirements. It’s measured from the formwork to the rebar before pouring concrete.

Lap length is the overlapping length required when connecting two rebar pieces end-to-end. It ensures proper transfer of forces between the bars. Lap length is typically 40-60 times the bar diameter, depending on concrete strength, bar size, and loading conditions. It’s needed when the required rebar length exceeds available bar lengths.