Complete kg/m Chart 6-50mm | Cost Estimation & Cutting Schedule 2026
Rebar weight calculates using steel density 7850 kg/m³ multiplied by cross-sectional area (πd²/4) where d represents nominal diameter in millimetres. Standard reinforcing bars manufactured to BS 4449 specifications provide consistent mass per unit length essential for accurate quantity takeoffs and cost estimation across construction projects. Deformed high-yield steel grades 460B and 500B dominate modern reinforced concrete construction offering superior bond characteristics through surface rib patterns enhancing composite action with surrounding concrete.
12m standard bar lengths optimize transportation efficiency and cutting schedules minimizing wastage through systematic nesting patterns. Diameter selection balances structural requirements with constructability where 8-12mm bars suit stirrups and links, 16-25mm serve primary longitudinal reinforcement, and 32mm+ diameters reserve for heavily loaded foundation elements and transfer structures. Accurate weight estimation prevents costly shortages while enabling competitive tender submissions through precise material budgeting.
6-8mm diameters construct shear stirrups, ties, and mesh reinforcement providing transverse shear resistance and concrete confinement. 10-16mm bars form distribution steel controlling shrinkage cracking and temperature effects while secondary longitudinal reinforcement in lightly loaded slabs and beams. 20-32mm diameters carry primary flexural and axial loads in columns, beams, and walls where structural analysis determines required areas based on design moments and forces.
40mm+ large diameters appear in pile caps, transfer girders, and deep foundations resisting concentrated heavy loads from tall structures. Bundle diameters maintain during bending operations preserving reinforcement effectiveness through controlled curvature radii preventing bar fracture and bond loss at bend locations.
Structural drawings specify bar marks with shapes, sizes, numbers, and lengths enabling systematic bar bending schedules generation. Centerline method calculates total length accounting for hook allowances and laps while detailed schedules verify against drawing dimensions ensuring accuracy. Software packages automate cutting optimization minimizing wastage below 5% through algorithmic nesting across multiple bar shapes and lengths.
Concrete cover requirements per exposure class determine minimum diameters and spacing preventing corrosion initiation while maintaining structural efficiency. Lap lengths calculate based on bond stress, bar diameter, and concrete strength ensuring force transfer continuity across splice locations without slippage or pullout failure.
Grade 460B provides minimum 460 N/mm² characteristic yield strength suitable for general building construction balancing cost and performance. Grade 500B achieves 500 N/mm² yield strength justifying premium pricing through 8-10% steel saving in heavily reinforced elements. Ductility requirements ensure 5% minimum elongation preventing brittle failure under overload conditions while rib geometry optimizes mechanical interlock with concrete matrix.
BS 4449 mandates chemical composition limits controlling carbon equivalent for weldability and fatigue resistance. Mill test certificates verify actual yield, tensile strength, and elongation exceeding specified minimums ensuring compliance throughout supply chain from production to site delivery.
Bars stored elevated above ground preventing surface contamination and corrosion initiation during construction periods. Bundle tagging identifies size, grade, and quantity facilitating inventory control and usage tracking. Lifting procedures utilize crane slings or forklifts preventing bar damage and personal injury during transportation to reinforcement cages and placement locations.
Cutting and bending operations employ hydraulic shears and mandrel benders maintaining dimensional accuracy and surface integrity. Quality inspection verifies hook angles, lap positions, and spacing tolerances ensuring compliance with structural drawings and placement tolerances specified in construction specifications.
Rebar pricing reflects global scrap steel markets, energy costs, and rolling mill capacity utilization creating volatile market conditions. Smaller diameters carry higher unit costs per kilogram due to increased processing relative to material volume while larger sizes benefit from economies of scale. Transportation distances, unloading facilities, and storage duration influence delivered pricing through freight charges and demurrage considerations.
Fixed price contracts stabilize budgeting through volume commitments while spot market purchases capture temporary price dips. Value engineering optimizes reinforcement through higher grade steel or adjusted detailing reducing total tonnage requirements without compromising structural capacity or durability performance.
| Diameter (mm) | Area (mm²) | Weight (kg/m) | Bars per Tonne | Typical Use |
|---|---|---|---|---|
| 6 | 28.4 | 0.222 | 4504 | Stirrups |
| 8 | 50.3 | 0.395 | 2532 | Stirrups/Links |
| 10 | 78.5 | 0.617 | 1621 | Distribution |
| 12 | 113 | 0.888 | 1126 | Main Bars |
| 16 | 201 | 1.579 | 633 | Columns/Beams |
| 20 | 314 | 2.466 | 405 | Heavy Columns |
| 25 | 491 | 3.853 | 259 | Foundation |
| 32 | 804 | 6.313 | 158 | Pile Caps |
| 40 | 1257 | 9.864 | 101 | Transfer Girders |
| Grade | Yield Strength | Elongation | Applications | Cost Premium |
|---|---|---|---|---|
| 460B | 460 MPa | 12% min | General buildings | Base |
| 500B | 500 MPa | 10% min | High-rise/Bridges | +8-12% |
Standard steel density produces exact kg/m weights: 16mm = 1.579kg/m, 20mm = 2.466kg/m, 25mm = 3.853kg/m.
12m bars optimize transport (33 bars/truck load) minimizing joints and cutting wastage.
Industry standard 3-7% cutting wastage included in material takeoffs ensuring supply continuity.
Grade 500B represents 85% usage providing 8-10% steel saving over 460B in main reinforcement.
Standard lap = 40×diameter ensuring full stress transfer through mechanical bond development.
16mm bars: 633m/tonne = ~53 bars (12m). Critical for accurate quantity scheduling.
Weight (kg/m) = 0.617 × d²/162 where d = diameter mm. 16mm: 0.617×256/162 = 1.579kg/m. Total weight = length × kg/m. Industry uses pre-calculated tables for accuracy.
12m represents global standard optimizing truck loads (33 bars/trailer) and cutting schedules. 11.7m common in some regions. Custom lengths increase cost through processing premiums.
500B provides 500MPa yield vs 460MPa enabling 8-10% steel reduction in heavily reinforced elements. Higher cost justified by material savings in high-rise and bridge construction.
3-7% cutting wastage standard depending on complexity. Straight bars: 3%, complex shapes: 7-10%. Bar bending schedules optimize nesting minimizing remnants through algorithmic cutting.
20-32mm typical for columns. 20mm light loads, 25mm medium, 32mm heavy. Minimum 12mm per code. Spacing 150-200mm ensures concrete placement without honeycombing.
40×diameter for tension laps, 25-30×diameter compression. Class B (tension) staggered minimum 2m. Hooks/cranks reduce straight lap requirements maintaining development length.
Grade 460B: £800-900/tonne, 500B: £900-1050/tonne delivered UK 2026. Prices fluctuate with scrap steel, energy costs, import duties. Fixed price contracts recommended for large projects.
16mm = 1.579kg/m. 1000kg ÷ 1.579 = 633m. 12m bars = 633÷12 = 52.75 = 53 bars/tonne. Critical for accurate material ordering and progress claims.
Suppliers: CA Group | Tata Steel | Standards: BS 4449