Steel Bar Weight Chart as per IS 1786 — Rebar Weight per Metre
If you've spent even a single day on a construction site in India, you know that one question comes up more often than any other: "What's the weight of this bar?" Whether you're preparing a Bar Bending Schedule, checking a supplier's delivery challan, verifying steel consumption at site, or estimating material cost for a tender — the unit weight of reinforcing steel bars is the number you reach for, every single time.
This article provides the definitive reference table for TMT (Thermo-Mechanically Treated) rebar weight as per IS 1786:2008, the Indian Standard for high-strength deformed steel bars. Bookmark this page — you'll need it again.
Quick Formula: Weight of any steel bar (kg/m) = D² / 162.2
Where D = bar diameter in mm. This single formula replaces the entire table for quick calculations.
Complete Rebar Weight Chart — IS 1786
The following table covers all standard TMT bar diameters available in India, from 6mm to 40mm. Weights are calculated for unit length (1 metre) and commonly needed lengths (12m standard bar).
| Bar Diameter (mm) | Cross-Section Area (mm²) | Weight per Metre (kg/m) | Weight per 12m Bar (kg) | Bars per Tonne | Common Use |
|---|---|---|---|---|---|
| 6 | 28.27 | 0.222 | 2.66 | 376 | Stirrups, ties, temperature steel |
| 8 | 50.27 | 0.395 | 4.74 | 211 | Stirrups, slab distribution bars |
| 10 | 78.54 | 0.617 | 7.40 | 135 | Slab main bars, beam stirrups |
| 12 | 113.10 | 0.888 | 10.66 | 94 | Slab main bars, beam bottom bars |
| 16 | 201.06 | 1.580 | 18.96 | 53 | Beam main bars, column bars |
| 20 | 314.16 | 2.469 | 29.63 | 34 | Beam main bars, column bars, footings |
| 25 | 490.87 | 3.858 | 46.30 | 22 | Heavy beams, columns, raft foundations |
| 28 | 615.75 | 4.834 | 58.01 | 17 | Heavy columns, pile caps, transfer beams |
| 32 | 804.25 | 6.317 | 75.80 | 13 | Heavy columns, pile foundations, retaining walls |
| 36 | 1017.88 | 7.990 | 95.88 | 10 | Heavy foundations, bridge piers |
| 40 | 1256.64 | 9.865 | 118.38 | 8 | Bridge girders, heavy piles, special structures |
Note: Standard bar length in India is 12 metres. Some manufacturers supply 11.5m or 12.2m — always verify actual length when calculating delivery weights.
The Formula Behind the Table
Every value in the table above is derived from one simple formula based on the density of steel (7850 kg/m³):
| Formula | Expression | Simplified |
|---|---|---|
| Weight per metre | W = (π/4) × D² × ρ / 10⁶ | W = D²/162.2 kg/m |
| Cross-section area | A = (π/4) × D² | A = 0.7854 × D² mm² |
| Bars per tonne | N = 1000 / (W × L) | N = 1000 / (W × 12) |
Where: D = diameter in mm, ρ = 7850 kg/m³ (density of steel), L = bar length in metres.
Site Shortcut: For a quick mental estimate, remember: D² ÷ 162. So a 16mm bar = 16×16/162 = 1.58 kg/m. A 20mm bar = 20×20/162 = 2.47 kg/m. This works for any diameter.
Fe 500 vs Fe 500D — Does Grade Affect Weight?
No. The weight per metre is identical for all grades — Fe 415, Fe 500, Fe 500D, Fe 550D, and even CRS (Corrosion Resistant Steel). Weight depends only on diameter and steel density (7850 kg/m³), which is the same for all carbon steel grades.
What differs between grades is the mechanical properties:
| Property | Fe 500 (IS 1786) | Fe 500D (IS 1786) | Fe 550D (IS 1786) |
|---|---|---|---|
| Yield Strength (min) | 500 MPa | 500 MPa | 550 MPa |
| UTS/YS Ratio (min) | 1.08 | 1.12 | 1.10 |
| Elongation (min) | 12% | 16% | 14.5% |
| Bend/Re-bend | Yes | Mandatory re-bend | Mandatory re-bend |
| Seismic Suitability | Limited | Yes — recommended | Yes — recommended |
Important: IS 13920 (Ductile Detailing of RC Structures for Seismic Resistance) recommends Fe 500D or Fe 550D for structures in Seismic Zones III, IV, and V due to their higher ductility (UTS/YS ratio ≥ 1.12) and mandatory re-bend test compliance. The 'D' suffix means higher ductility — critical for earthquake resistance.
How to Calculate Steel Quantity from BBS
The weight chart is essential for converting a Bar Bending Schedule (BBS) from lengths to weights. Here's the standard workflow:
| Step | Action | Example |
|---|---|---|
| 1 | List all bars with diameter and cutting length | 16mm dia, cutting length 4.5m, quantity 24 nos |
| 2 | Calculate total length = cutting length × quantity | 4.5 × 24 = 108.0 m |
| 3 | Look up unit weight from chart (or use D²/162) | 16mm = 1.580 kg/m |
| 4 | Calculate weight = total length × unit weight | 108.0 × 1.580 = 170.64 kg |
| 5 | Add wastage allowance (2-5% typical) | 170.64 × 1.03 = 175.76 kg |
Use our free Bar Bending Schedule Calculator to automate this entire process — input bar shape, diameter, and dimensions, and get cutting length + weight instantly.
How to Verify Supplier Delivery Weight
Rebar is purchased by weight (per tonne) but delivered as counted bars. Here's how to verify you're getting what you paid for:
| Check | Method | Acceptable Tolerance |
|---|---|---|
| Count bars per bundle | Count all bars in 2-3 random bundles | Must match challan quantity |
| Measure actual length | Tape 5 random bars | 12m ± 100mm (IS 1786) |
| Measure actual diameter | Vernier caliper on 5 random bars | ±0.6mm for 12-16mm, ±0.7mm for 20-32mm |
| Weigh random bars | Weigh 3 bars of each diameter on calibrated scale | ±3% of theoretical weight (IS 1786 Cl. 9.2) |
| Calculate delivery weight | Count × theoretical weight per bar | Compare with weighbridge slip |
Site Tip: Some unscrupulous suppliers deliver bars that are 0.3-0.5mm undersize — a 16mm bar that's actually 15.5mm weighs 6% less. Always verify diameter with a Vernier caliper. A 6% shortfall on a 100-tonne order means you lose 6 tonnes of steel worth ₹3-4 lakh.
Rebar Weight Comparison: IS vs ASTM vs BS
For engineers working on international projects or comparing with imported steel, here's how Indian rebar sizes compare:
| IS 1786 (India) | ASTM A615 (US) — Nearest | BS 4449 (UK/EU) — Nearest | Weight (kg/m) |
|---|---|---|---|
| 8mm | #3 (9.5mm) | 8mm | 0.395 |
| 10mm | #3 (9.5mm) | 10mm | 0.617 |
| 12mm | #4 (12.7mm) | 12mm | 0.888 |
| 16mm | #5 (15.9mm) | 16mm | 1.580 |
| 20mm | #6 (19.1mm) | 20mm | 2.469 |
| 25mm | #8 (25.4mm) | 25mm | 3.858 |
| 32mm | #10 (32.3mm) | 32mm | 6.317 |
Note: ASTM uses imperial bar numbers (#3 through #18) where the number represents eighths of an inch. IS and BS use metric (mm) diameters directly. IS and BS sizes are identical; ASTM sizes are slightly different.
Steel Quantity Thumb Rules for Quick Estimation
When you need a rough estimate before detailed BBS is available, use these industry thumb rules:
| Structural Element | Steel Quantity (kg/m³ of concrete) | Typical Bar Sizes |
|---|---|---|
| Slab (one-way) | 60–90 kg/m³ | 8mm, 10mm, 12mm |
| Slab (two-way) | 70–100 kg/m³ | 8mm, 10mm, 12mm |
| Beam | 120–180 kg/m³ | 16mm, 20mm, 25mm + 8mm stirrups |
| Column | 150–250 kg/m³ | 16mm, 20mm, 25mm, 32mm + 8mm ties |
| Footing | 50–80 kg/m³ | 12mm, 16mm, 20mm |
| Retaining wall | 80–120 kg/m³ | 12mm, 16mm, 20mm |
| Overall building average | 80–120 kg/m³ | Mix of all sizes |
Example: For a residential building with 500 m³ of concrete, estimated steel = 500 × 100 (avg) = 50,000 kg = 50 tonnes. At ₹65,000/tonne, steel cost ≈ ₹32.5 lakh. This is a preliminary estimate — always prepare a detailed BBS for procurement.
Quality Tests for Rebar at Site (IS 1786)
Before using any rebar, the following tests must be performed as per IS 1786 and IS 456:
| Test | Requirement (Fe 500D) | Test Standard | Frequency |
|---|---|---|---|
| Tensile strength | ≥ 545 MPa (UTS/YS ≥ 1.08) | IS 1608 | Every 25 tonnes or part thereof |
| Yield strength | ≥ 500 MPa | IS 1608 | Every 25 tonnes |
| Elongation | ≥ 16% (for Fe 500D) | IS 1608 | Every 25 tonnes |
| Bend test | No crack on bending around mandrel | IS 1599 | Every 25 tonnes |
| Re-bend test | No crack after bending, ageing, re-bending | IS 1786 Cl. 8.5 | Every 25 tonnes (mandatory for 'D' grade) |
| Weight check | ±3% of theoretical weight | IS 1786 Cl. 9.2 | Every delivery |
Download our free Rebar Receiving Inspection Checklist — a ready-to-use QA/QC format with all IS 1786 checkpoints for incoming rebar inspection at site.
Frequently Asked Questions
What is the weight of 1 metre of 12mm steel bar?
0.888 kg (approximately 0.89 kg/m). Calculated as 12² ÷ 162.2 = 0.888 kg/m. A standard 12m bar weighs 10.66 kg.
How many 12mm bars in 1 tonne?
94 bars of 12m length. Calculated as 1000 kg ÷ (0.888 × 12) = 93.8, rounded to 94 bars per tonne.
What is the formula for steel bar weight?
Weight (kg/m) = D² ÷ 162.2, where D is bar diameter in mm. This is derived from: Weight = (π/4) × D² × 7850 / 10⁶. The constant 162.2 = 10⁶ / (π/4 × 7850).
What is the weight tolerance for rebar?
±3% as per IS 1786 Clause 9.2. For example, a 16mm bar (theoretical 1.580 kg/m) should weigh between 1.533 and 1.627 kg/m.
Is Fe 500D heavier than Fe 500?
No. Both have identical weight per metre. The 'D' suffix indicates higher ductility (more elongation, better UTS/YS ratio), not different weight or dimensions.
What diameter of rebar is used for slabs?
Typically 8mm, 10mm, or 12mm for residential slabs. 10mm is most common for main bars, 8mm for distribution bars. For commercial/industrial slabs with heavy loads, 12mm or 16mm may be used.
Related Resources
- IS 1786:2008 — Full Code Details — Key clauses, values, FAQ, and international comparison
- Bar Bending Schedule Calculator — Free online BBS calculator with cutting length and weight
- Rebar Receiving Inspection Checklist — QA/QC template for steel receiving at site
- Tensile / Bend / Re-bend Test Report — QA/QC format for rebar testing
- Construction Cost Calculator — Estimate total construction cost including steel
- IS 1786 vs ASTM A615 — International Comparison
References
- IS 1786:2008 — High Strength Deformed Steel Bars and Wires for Concrete Reinforcement — Bureau of Indian Standards
- IS 456:2000 — Plain and Reinforced Concrete — Code of Practice — Clause 5.6 (Reinforcement)
- IS 13920:2016 — Ductile Detailing of Reinforced Concrete Structures Subjected to Seismic Forces
- IS 1608:2005 — Metallic Materials — Tensile Testing at Ambient Temperature
- SP 16:1980 — Design Aids for Reinforced Concrete to IS 456