🇮🇳 IS 1786:2008 Compliant

Steel Bar Weight Calculator

Calculate TMT rebar weight instantly using the d²/162 formula. Single bars, multiple diameters, or full bar schedules — all in one tool.

IS 1786:2008 IS 456:2000 8mm – 40mm Fe 415 / Fe 500 / Fe 550

📐 Select Bar Diameter

Diameter (mm)

∅

Length per Bar

Number of Bars

nos

Steel Grade

Wastage / Lapping (%)

Rate per kg (₹)

₹

/kg

⚠️ Please enter valid input values.

📊 Results

Add multiple bar entries — different diameters, lengths and quantities. Calculates total weight for the entire bar bending schedule.

S.NoDia (mm)Description Length (m)NosWt (kg)

Wastage / Lapping (%)

Rate per kg (₹)

₹

/kg

Steel Grade

📋 Bar Schedule Results

Standard unit weight of TMT steel bars as per IS 1786:2008 using the d²/162.27 formula. Click any bar to auto-fill the Quick Calculator.

Dia (mm)	Formula	Unit Wt (kg/m)	1 bar @ 6m	1 bar @ 12m	100 bars @ 12m

Formula: Unit Weight (kg/m) = d² ÷ 162.27 | Density of steel = 7850 kg/m³ | Values as per IS 1786:2008

Steel Bar Weight Calculator — How It Works

This free online steel bar weight calculator is built for Indian civil engineers, site supervisors, structural designers, and quantity surveyors. Whether you're estimating TMT rebar for a building column, calculating the bar bending schedule (BBS) for a slab, or simply verifying material procurement, this tool gives you instant, accurate results as per IS 1786:2008 and IS 456:2000.

The d²/162 Formula — Explained

    Unit Weight (kg/m) = d² ÷ 162

    where d = diameter of the bar in millimetres

This formula is derived from the fundamental physics of steel density:

Cross-sectional area of a round bar = π/4 × d² (mm²)
Density of mild/TMT steel = 7850 kg/m³ = 0.00785 g/mm³
Weight per metre = Area × Density = (π/4 × d²) × 0.00785 g/mm³
Simplified: Weight = d² × (π/4 × 0.00785) = d² / 162.27 ≈ d² / 162

The value 162.27 is a constant derived from the steel density and unit conversion factors. In practice, Indian engineers round this to 162 for quicker field calculations.

Example Calculation — M20 Slab

Suppose you need to calculate weight for:

Diameter: 12 mm
Length per bar: 6 m
Number of bars: 50 nos

Step 1: Unit weight = 12² ÷ 162 = 144 ÷ 162 = 0.888 kg/m

Step 2: Weight per bar = 0.888 × 6 = 5.33 kg

Step 3: Total weight = 5.33 × 50 = 266.7 kg

Adding 5% wastage/lapping: 266.7 × 1.05 = 280.0 kg ≈ 0.28 tonnes

Standard Unit Weights of TMT Bars (IS 1786:2008)

Diameter (mm)	Unit Weight (kg/m)	Weight per 6m bar	Weight per 12m bar
8 mm	0.395 kg/m	2.37 kg	4.74 kg
10 mm	0.617 kg/m	3.70 kg	7.40 kg
12 mm	0.888 kg/m	5.33 kg	10.66 kg
16 mm	1.580 kg/m	9.48 kg	18.96 kg
20 mm	2.469 kg/m	14.81 kg	29.63 kg
25 mm	3.858 kg/m	23.15 kg	46.30 kg
32 mm	6.313 kg/m	37.88 kg	75.76 kg
40 mm	9.864 kg/m	59.18 kg	118.37 kg

TMT Steel Grades Used in India

As per IS 1786:2008, TMT bars are available in the following grades, each with different yield strength (fy):

Fe 415 — 415 N/mm² yield strength. Used in general residential construction.
Fe 500 / Fe 500D — 500 N/mm² yield strength. Most widely used in India for RCC columns, beams, slabs.
Fe 550 / Fe 550D — 550 N/mm² yield strength. High-rise buildings, industrial structures.
Fe 600 — 600 N/mm² yield strength. Heavy engineering, bridges, dams.

Note: The 'D' suffix (e.g., Fe 500D) indicates enhanced ductility — mandatory for earthquake-resistant structures as per IS 13920.

What is a Bar Bending Schedule (BBS)?

A Bar Bending Schedule (BBS) is a detailed document prepared by structural engineers and quantity surveyors listing all reinforcement bars in an RCC member — their diameter, shape, cutting length, number, and total weight. The BBS is used for:

Material procurement and cost estimation
Site supervision and quality control
Billing and contractor payments
Structural auditing and as-built documentation

Use the Bar Schedule tab above to calculate multi-bar BBS totals instantly.

Why Use This Calculator Instead of Manual Calculation?

⚡ Instant results — no pen-paper or Excel needed at site
✅ IS 1786:2008 compliant values — verified formula constants
📋 Full bar schedule — add 10+ different diameter entries at once
💰 Cost estimation — built-in rate per kg and total cost output
📱 Mobile-friendly — works perfectly on site with any device
📤 Copy results — paste into WhatsApp or email instantly

Lapping Length for TMT Bars (IS 456:2000)

When bars need to be joined (lapped), extra length is required. As per IS 456:2000, the minimum lap length is:

Tension zone: 45 × diameter (e.g., 45 × 16mm = 720mm)
Compression zone: 24 × diameter (e.g., 24 × 16mm = 384mm)
Minimum in any case: 300 mm

This calculator adds a configurable wastage + lapping percentage (default 5%) to account for these overlaps and site cutting losses.

❓ Frequently Asked Questions

The standard formula is: Weight (kg) = (d² / 162) × Length (m) × Number of bars, where d is the diameter in mm. This is derived from the steel density (7850 kg/m³) and cross-sectional area calculation. The precise divisor is 162.27, commonly rounded to 162 for field use.

The unit weight of a 12mm steel bar is 0.888 kg/m (calculated as 12² ÷ 162 = 144 ÷ 162 = 0.888 kg/m). A standard 12m bar weighs 10.67 kg and a 6m bar weighs 5.33 kg.

In India, TMT bars are typically supplied in bundles of approximately 1 MT (1000 kg) or custom cut lengths. The number of bars per bundle depends on the diameter — for 12mm bars at 12m length, roughly 93–94 bars make 1 MT. Some suppliers sell in 20 kg bundles for small orders.

Fe 415 has a yield strength of 415 N/mm² while Fe 500 has 500 N/mm². Fe 500 is stronger and now more commonly used across India. Fe 500D has the same strength but enhanced ductility, making it suitable for earthquake-prone zones as per IS 13920. IS 456:2000 permits both grades for RCC construction.

The 5% wastage accounts for: (1) cutting waste — off-cuts when bars are cut to required lengths, (2) lapping lengths — overlap required when bars are joined (45×d in tension zones), and (3) bending allowance — extra length consumed in hooks, bends and cranks. For complex structures, 7–10% wastage is more realistic.

Weight of 1m of 20mm bar = 20² ÷ 162 = 400 ÷ 162 = 2.469 kg/m. A standard 12m bar of 20mm weighs 29.63 kg.

For residential home construction, Fe 500D TMT bars from reputed brands (TATA Tiscon, JSW Neosteel, Vizag Steel) are recommended. The 'D' grade offers better ductility (elongation ≥ 16%) which is crucial for earthquake safety as per IS 13920. For normal residential use in non-seismic zones, Fe 500 is sufficient and IS 456:2000 compliant.

For a typical M20 grade, 125mm thick two-way RCC slab of 1000 sq ft (93 m²): Main bars (12mm @ 150mm c/c) and distribution bars (8mm @ 200mm c/c). Approximate steel requirement: 65–80 kg per m² of slab area, so 93 × 70 ≈ 6,500 kg (6.5 MT). Use our Bar Schedule calculator above for precise calculations with your specific spacing.