Calculate rebar weight, total quantity, and material cost for concrete slabs, beams, columns, and footings.
Steel Reinforcement Calculator
Centre-to-centre spacing
–Total Weight (kg)
–Tonnes
–No. of Bars
–Linear Metres
–Est. Material Cost
Reinforcement Steel Reference Table
Selecting the correct rebar size and spacing is governed by structural engineering calculations and local building codes. The reinforcement steel calculator above provides material quantity estimates for budgeting and ordering purposes. Always have a qualified structural engineer specify reinforcement for any load-bearing element.
Bar Size
Diameter (mm)
Weight (kg/m)
Area (mm²)
Common Use
Ø8
8
0.395
50.3
Light slabs, stirrups
Ø10
10
0.617
78.5
Slabs, footings
Ø12
12
0.888
113.1
Beams, slabs
Ø16
16
1.578
201.1
Beams, columns
Ø20
20
2.466
314.2
Columns, heavy beams
Ø25
25
3.853
490.9
Heavy columns, bridges
Ø32
32
6.313
804.2
Major structural elements
⚙️ Rule of thumb: Add 5–10% waste factor for laps, offcuts, and bending losses. For complex structures, use 15%. The calculator above uses the net quantity — add your waste factor before ordering.
Typical minimum reinforcement ratios for concrete slabs range from 0.12–0.25% of the cross-sectional area depending on design standards (ACI, Eurocode, or local codes). A standard domestic slab might use Ø12 bars at 150mm spacing each way. Always verify with a structural engineer for load-bearing applications.
Rebar weight formula: Weight (kg) = (Diameter in mm)² / 162 × Length (m). For example, a 10m bar of Ø16 rebar weighs: (16²/162) × 10 = 2.56 × 10 = 15.8 kg. Alternatively, Ø16 has a unit weight of 1.578 kg/m, so 10m × 1.578 = 15.78 kg.
Minimum concrete cover protects reinforcement from corrosion. Typical values: 20–25mm for internal slabs, 25–40mm for external exposed elements, 40–75mm for foundations in aggressive soils. Cover requirements increase with exposure class and decrease with higher-strength concrete mixes.