Reinforcement Steel Calculator

Calculator A — Weight of a Bar or a Set of Bars

Pick the bar diameter, enter how many bars and the cut length of each — the weight comes straight from the d²/162 unit weight.

Single bar / set weight

Bar diameter (mm)

Number of bars (nos)

Length of each bar (m)

How this is worked out

Unit weight of bar (kg/m) = d² / 162 (d = diameter in mm) Weight of one bar (kg) = (d² / 162) × length (m) Weight of the set (kg) = weight of one bar × number of bars Example — 24 nos of 10 mm bars, 4.50 m each: unit weight = 10² / 162 = 0.617 kg/m set weight = 0.617 × 4.50 × 24 ≈ 66.67 kg

The d²/162 rule comes from the density of steel (7850 kg/m³) applied to the nominal cross-section of a round bar — d²/162.28 exactly, rounded to 162 in every works office. It applies to plain and deformed (TMT/tor) bars alike, since both are sold on nominal diameter.

Calculator B — Mini Bar-Bending Schedule

Add one row per bar mark — diameter, number of bars and cut length. The schedule totals the steel dia-wise (the way a supplier invoices it and the way it enters the MB) and gives the grand total in kg and quintals.

Bar-bending schedule

S.No	Dia (mm)	Nos	Cut length (m)	Weight (kg)

How this is worked out

Row weight (kg) = (d² / 162) × cut length (m) × nos Dia-wise total (kg) = Σ row weights of that diameter Grand total (kg) = Σ all row weights Grand total (quintal) = grand total (kg) ÷ 100 (1 quintal = 100 kg; 1 MT = 1000 kg)

Cut length means the straight length of the bar before bending, including hooks, bends and laps as scheduled on the drawing. A full bar-bending schedule also records shape codes and bend deductions — this mini schedule is for quick quantity checks against the details of measurement.

Unit Weights of Reinforcement Bars (d²/162)

Memorise the first four — they cover most slab and beam steel you will ever measure.

Diameter (mm)	Unit weight (kg/m)	Weight of 12 m bar (kg)	Metres per MT (approx.)
6	0.222	2.667	4500
8	0.395	4.741	2531
10	0.617	7.407	1620
12	0.889	10.667	1125
16	1.580	18.963	633
20	2.469	29.630	405
25	3.858	46.296	259
32	6.321	75.852	158

Lap length. Where bars are joined by lapping, the lap adds to the steel quantity — typically 50d in tension (e.g. 500 mm for a 10 mm bar, 800 mm for 16 mm) and less in compression. The governing value is the development length worked out under IS 456 for the grade of concrete and steel actually used, so always follow the structural drawing or the design engineer's schedule rather than a thumb rule. Laps in a section should be staggered, and lapping is avoided at points of maximum stress.

Cover blocks. Reinforcement must sit at its designed depth, held there by cover blocks (cement-mortar biscuits or PVC spacers) of the specified nominal cover — commonly of the order of 20 mm for slabs, 25 mm for beams, 40 mm for columns and 50 mm for footings, subject to IS 456 exposure-condition requirements and the drawing. Cover blocks are incidental to the reinforcement item; while checking a bill, verify cover was actually maintained before the concrete measurement is admitted.

These figures are an educational aid for quick checks. Always verify against your organisation's schedule of rates, the governing IS codes and the contract before use.

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