Total Rebar Weight
0 kg
Including wastage and lap allowance
Calculate Reinforcement Steel Requirements
Professional Rebar Quantity & Weight Estimator for Concrete
Rebar (reinforcing bar) is essential steel reinforcement used to strengthen concrete structures against tensile forces. Calculating accurate rebar quantities prevents material shortages, reduces waste, and ensures structural integrity. For contractors working with imperial units or US-based calculations, you can also use this concrete rebar calculator designed for American construction standards. Our rebar calculator 2026 uses BS 4449:2005 standards to calculate reinforcement requirements for slabs, foundations, beams, columns, and walls.
UK rebar is manufactured in sizes from 6mm to 50mm diameter, with common construction sizes ranging from 8mm to 32mm. Standard grades include B500B (460 MPa yield strength) for general construction and B500C for enhanced seismic resistance. Understanding rebar specifications, spacing requirements, and weight calculations ensures proper structural design according to 2026 building regulations and Eurocode 2 standards.
Calculate reinforcement quantity, weight, and material requirements
Rebar specifications in the UK follow BS 4449:2005 "Steel for the reinforcement of concrete - Weldable reinforcing steel". This standard defines mechanical properties, dimensions, tolerances, and testing requirements for reinforcement bars. Our rebar calculator uses these standards to ensure accurate specifications for 2026 construction projects compliant with Eurocode 2.
| Diameter (mm) | Cross-Section Area (mm²) | Weight (kg/m) | Weight per 12m Bar (kg) | Common Applications |
|---|---|---|---|---|
| 6mm | 28.3 | 0.222 | 2.66 | Light mesh, stirrups, ties |
| 8mm | 50.3 | 0.395 | 4.74 | Slabs, stirrups, light walls |
| 10mm | 78.5 | 0.617 | 7.40 | Standard slabs, foundations |
| 12mm | 113.1 | 0.888 | 10.66 | Beams, heavy slabs, columns |
| 16mm | 201.1 | 1.579 | 18.95 | Main beams, columns, retaining walls |
| 20mm | 314.2 | 2.466 | 29.59 | Heavy columns, large beams |
| 25mm | 490.9 | 3.854 | 46.25 | Industrial columns, bridge beams |
| 32mm | 804.2 | 6.313 | 75.76 | Heavy industrial, large structures |
| 40mm | 1256.6 | 9.864 | 118.37 | Major infrastructure, dams, bridges |
Understanding rebar calculation formulas ensures accurate quantity estimation for structural concrete. Our rebar calculator applies these fundamental formulas adjusted for application type, spacing requirements, and wastage allowances according to construction best practices.
📐 Basic Rebar Calculation Formulas:
Dimensions: 10m length × 8m width
Rebar: 10mm @ 150mm spacing both ways
Longitudinal bars: (10,000 / 150) + 1 = 68 bars
Transverse bars: (8,000 / 150) + 1 = 55 bars
Length each longitudinal: 8m (approx)
Length each transverse: 10m (approx)
Total length: (68 × 8) + (55 × 10) = 1,094m
Total weight: 1,094 × 0.617 = 675 kg
Length: 20m continuous strip footing
Rebar: 4 bars of 12mm longitudinal
Stirrups: 8mm @ 200mm spacing
Longitudinal: 4 bars × 20m = 80m
Number of stirrups: (20,000 / 200) = 100
Perimeter each: ~1.2m (varies by footing width)
Stirrup length: 100 × 1.2 = 120m
Total weight: (80 × 0.888) + (120 × 0.395) = 118 kg
UK rebar grades are defined by BS 4449:2005 with designations based on characteristic yield strength and ductility class. Grade selection depends on structural requirements, seismic considerations, and welding needs. Our rebar calculator supports all standard UK grades for 2026 construction.
Yield Strength: 500 MPa (characteristic)
Tensile Strength: Minimum 540 MPa
Ductility Class: B (Medium ductility)
Elongation: Minimum 5.0% (Agt)
Applications: General construction, residential, commercial buildings
Weldability: Limited welding (may require pre-heating)
Yield Strength: 500 MPa (characteristic)
Tensile Strength: Minimum 575-750 MPa
Ductility Class: C (High ductility)
Elongation: Minimum 7.5% (Agt)
Applications: Seismic zones, structures requiring high ductility
Weldability: Good weldability without pre-heating
Yield Strength: 500 MPa (characteristic)
Tensile Strength: Minimum 525 MPa
Ductility Class: A (Standard ductility)
Elongation: Minimum 2.5% (Agt)
Applications: Non-seismic structures, basic reinforcement
Weldability: Not recommended for welding
Yield Strength: 500 MPa (characteristic)
Coating: Hot-dip galvanized or epoxy-coated
Ductility Class: B (Medium ductility)
Elongation: Minimum 5.0% (Agt)
Applications: Coastal structures, aggressive environments, marine works
Cost Premium: 40-80% more than standard B500B
Grade: Typically 316L or 1.4401
Yield Strength: Minimum 500 MPa
Corrosion Resistance: Excellent (marine, chemical exposure)
Elongation: Minimum 15%
Applications: Bridges, jetties, wastewater treatment, heritage restoration
Cost Premium: 8-10 times cost of carbon steel
Material: Glass or carbon fiber composite
Tensile Strength: 600-2,000 MPa (varies by type)
Corrosion Resistance: Completely corrosion-proof
Weight: 75-80% lighter than steel
Applications: MRI facilities, corrosive environments, electromagnetic sensitivity
Cost Premium: 3-5 times cost of steel rebar
Proper rebar spacing ensures adequate concrete cover, prevents honeycombing, and maintains structural integrity. Eurocode 2 and BS 8110 specify minimum and maximum spacing requirements based on member type, concrete aggregate size, and structural loads. Our rebar calculator considers these requirements for accurate placement specifications.
✅ Standard Spacing Requirements:
| Application | Typical Spacing | Minimum Spacing | Maximum Spacing | Notes |
|---|---|---|---|---|
| Residential Slab (100mm) | 150-200mm | 100mm | 300mm | Both directions, 10mm bars typical |
| Commercial Slab (150mm) | 125-150mm | 100mm | 400mm | Heavier loading, 12mm bars typical |
| Foundation / Footing | 150-200mm | 125mm | 300mm | 12mm minimum diameter recommended |
| Beam Main Bars | 50-100mm | 40mm | 300mm | Depends on beam width and loads |
| Beam Stirrups | 150-250mm | 100mm | 0.75 × beam depth | Closer spacing near supports |
| Column Main Bars | Corner + intermediate | 50mm clear | 300mm (between bars) | Minimum 4 bars, typically 6-12 bars |
| Column Ties/Links | 150-300mm | Lesser of 12×bar dia or 300mm | 450mm | Closer spacing at lap locations |
| Wall Vertical | 200-300mm | 150mm | 400mm or 3×wall thickness | Both faces for walls >200mm thick |
| Wall Horizontal | 200-300mm | 150mm | 400mm or 3×wall thickness | Distribution reinforcement |
Concrete cover protects reinforcement from corrosion, fire, and mechanical damage. Cover requirements depend on exposure class, member type, and design fire resistance according to Eurocode 2 (BS EN 1992). Adequate cover ensures durability and structural performance throughout the design life.
| Exposure Class | Environment | Minimum Cover (mm) | Nominal Cover (mm) |
|---|---|---|---|
| XC1 | Dry or permanently wet (internal) | 15 | 25 |
| XC2 | Wet, rarely dry (foundations) | 25 | 35 |
| XC3 | Moderate humidity (sheltered external) | 25 | 35 |
| XC4 | Cyclic wet/dry (external surfaces) | 30 | 40 |
| XD1 | Moderate humidity with chlorides | 35 | 45 |
| XD2 | Wet with chlorides (de-icing salts) | 40 | 50 |
| XD3 | Cyclic wet/dry with chlorides | 45 | 55 |
| XS1 | Marine exposure (airborne salt) | 40 | 50 |
| XS2 | Marine submerged | 45 | 55 |
| XS3 | Marine tidal/splash zone | 50 | 60 |
Lap splices transfer forces between reinforcement bars through bond stress in the surrounding concrete. Proper lap lengths prevent bond failure and ensure continuity of reinforcement. Lap requirements are specified in Eurocode 2 based on bar diameter, concrete grade, and stress conditions.
⚠️ Standard Lap Length Formula:
Rebar prices in the UK vary based on grade, quantity, diameter, and supplier. Understanding 2026 pricing helps create accurate construction budgets. Prices include standard B500B grade delivered in bulk quantities; expect premiums for small orders, cut-and-bent services, or specialized grades.
| Diameter | Price per Tonne (£) | Price per 12m Bar (£) | Typical MOQ |
|---|---|---|---|
| 6mm | £750 - £950 | £2.00 - £2.50 | 1 tonne (350+ bars) |
| 8mm | £700 - £900 | £3.30 - £4.30 | 1 tonne (200+ bars) |
| 10mm | £650 - £850 | £4.80 - £6.30 | 1 tonne (135+ bars) |
| 12mm | £650 - £850 | £6.90 - £9.00 | 1 tonne (95+ bars) |
| 16mm | £650 - £850 | £12.30 - £16.10 | 1 tonne (53+ bars) |
| 20mm | £650 - £850 | £19.20 - £25.15 | 1 tonne (34+ bars) |
| 25mm | £650 - £850 | £30.00 - £39.30 | 1 tonne (22+ bars) |
| 32mm | £700 - £900 | £53.00 - £68.20 | 1 tonne (13+ bars) |
💰 Additional Cost Considerations: