Every contractor needs the same lookup table eventually: what's the weight of a 12m TMT rod by diameter? Here it is, plus a couple of worked examples for typical residential orders, plus the Steel Calculator that handles multi-diameter BOMs for you.

🧮 Skip the math: Use the Steel Weight Calculator — add as many diameter + quantity rows as your BOM needs, get total kg + tonnes + cost.

The formula

Weight per metre = D² ÷ 162  (kg/m, where D is diameter in mm)

This is the standard industry formula used by every TMT supplier in India. The 162 is a derived constant from steel density (7,850 kg/m³) and the cross-section area of a circle.

Standard TMT weight chart

For 12-metre rods (the standard length supplied in India):

Diameter Weight per metre Weight per 12 m rod Typical use
6 mm 0.222 kg/m 2.67 kg Stirrups, small ties
8 mm 0.395 kg/m 4.74 kg Slab distribution, stirrups
10 mm 0.617 kg/m 7.41 kg Slab main reinforcement
12 mm 0.889 kg/m 10.67 kg Beams, slab main
16 mm 1.580 kg/m 18.96 kg Columns, beam main
20 mm 2.469 kg/m 29.63 kg Heavy columns, large beams
25 mm 3.858 kg/m 46.30 kg Industrial, foundations
32 mm 6.321 kg/m 75.85 kg Large structures, bridges

Rule of thumb to remember: 8mm rod ≈ 5 kg per 12m, 12mm rod ≈ 10 kg, 16mm rod ≈ 20 kg.

Worked example 1: 1000 sqft residential slab

Typical 1000 sqft G+0 slab needs ~3.5 tonnes of TMT distributed across diameters:

Diameter Quantity (12m rods) Total weight Price (@ ₹62/kg)
8 mm (stirrups + distribution) 180 rods 854 kg ₹52,950
10 mm (slab top) 100 rods 741 kg ₹45,940
12 mm (slab main) 130 rods 1,387 kg ₹85,990
16 mm (beam main) 30 rods 569 kg ₹35,280
Total 440 rods 3,551 kg ₹2,20,160

Worked example 2: G+1 column reinforcement

For a typical G+1 Chennai home, 6 columns at 230 × 450 mm × 20 ft, each needs:

  • 6 × 16 mm vertical bars (each 20 ft = 6.1 m)
  • 16 mm stirrups @ 200 mm spacing (~100 stirrups × 1.4 m each = 14 m of 8 mm)

Per column:

  • 16 mm: 6 × 6.1 m = 36.6 m → 36.6 × 1.58 kg/m = 57.8 kg
  • 8 mm: 14 m × 0.395 = 5.5 kg

For all 6 columns:

  • 16 mm: 347 kg → ~₹21,500
  • 8 mm: 33 kg → ~₹2,050

Total column reinforcement: ~380 kg, ~₹23,550 in steel.

Worked example 3: Compound wall foundation

100 m compound wall, 9-inch wide × 4 ft deep foundation:

  • 4 × 12 mm bars running longitudinally = 400 m of 12 mm
  • 8 mm stirrups @ 200 mm = 500 × 1.2 m = 600 m of 8 mm
12 mm: 400 × 0.889 = 356 kg
8 mm: 600 × 0.395 = 237 kg
Total: 593 kg

Cost at ₹62/kg = ~₹36,800.

Brand + grade considerations

For Chennai builds, our recommendations:

Grade When Price (Jun 2026, ex-Sholinganallur)
Fe 500 Older standard, mostly phased out ~₹56-60/kg
Fe 500D Standard for G+0 residential ₹58-62/kg
Fe 550D G+1+ residential, all commercial ₹62-66/kg
Fe 550D CRS Coastal Chennai (east of OMR / on ECR) ₹66-72/kg

CRS (Corrosion Resistant Steel) is worth the ₹3-5/kg premium if your site is anywhere with salt-laden air. See our TMT Grades guide for the full breakdown.

Brand options at Suppliable: ARS Steels (Chennai-based, our most-ordered), Tata Tiscon (premium), ISteel (CRS variants), Arun (mid-tier).

Minimum order quirks

Most TMT brands require 500 kg minimum per diameter for direct site delivery. So if you only need 200 kg of 16 mm for a small job, you have two options:

  1. Combine with other diameters to hit the per-diameter minimum
  2. WhatsApp us to confirm availability for smaller quantities — we can often combine with another customer's delivery

Use the calculator

For your actual BOM, open the Steel Weight Calculator, add a row per diameter with quantities, and get the total weight + cost in 2 seconds. Tap WhatsApp to send the full BOM to our team — they'll quote with live brand prices and delivery window.

Building in Chennai? WhatsApp +91 87786 27926 with your steel BOM and we'll quote within an hour.

🧮 Free tool: Try our Steel Weight Calculator — multi-diameter BOM table, instant total.