Steel / rebar weight calculator
Work out the weight of TMT steel reinforcement from its bar diameter, length and quantity — using the standard d² ÷ 162.28 unit-weight rule.
Get the unit weight per metre, total weight in kg and tonnes, the number of 12 m stock bundles, and an optional material cost from a Rs/kg rate. A material-takeoff tool, computed in your browser.
Bar details
Nominal rebar size — e.g. 8, 12, 16, 20, 25 or 32 mm.
Cut length of one bar. Stock bars are usually 12 m.
How many bars of this size and length.
Enter a price per kg to estimate the steel cost.
Total steel weight
532.4 kg
≈ 0.532 tonne of 12 mm bar
Unit weight
0.887 kg/m
Per bar
10.65 kg
Total length
600.0 m
12 m bundles
50.0
Unit weight
0.887 kg/m
| Unit-weight formula | w = d² ÷ 162.28 (kg/m) |
| Weight per metre | 12² ÷ 162.28 = 0.887 kg/m |
| Weight per bar | 0.887 × 12 m = 10.65 kg |
| Total weight | 10.65 × 50 bars = 532.4 kg |
| Stock bundles (12 m) | 600.0 m ÷ 12 m = 50.0 lengths |
A material-takeoff estimate using the standard d²/162.28 unit-weight rule for round steel bars. Actual delivered weight varies with the manufacturer's rolling tolerance (IS 1786 permits a few percent either way), cut waste and laps. Bundle counts assume the 12 m stock length common in Nepal; confirm available lengths with your supplier.
From bar diameter to tonnes of steel
The weight of a round steel bar follows directly from its diameter; the rest is multiplying out the length and quantity, then converting to stock bundles and cost.
Unit weight
Weight per metre = d² ÷ 162.28, with the diameter d in mm. It comes from steel's density (7850 kg/m³) and a circular cross-section.
Total weight
Multiply the unit weight by the length of one bar, then by the number of bars, to get the total kilograms (and tonnes).
Bundles & cost
Divide total length by the 12 m stock bar length for the number of full lengths; multiply total weight by the Rs/kg rate for material cost.
Steel weight, answered
How do you calculate the weight of a steel rebar?+
Use the unit-weight formula w = d² ÷ 162.28, where d is the bar diameter in millimetres and w is the weight per metre in kg/m. Multiply by the length of one bar to get the weight per bar, and by the number of bars for the total. For example a 12 mm bar weighs 12² ÷ 162.28 ≈ 0.888 kg per metre.
Where does the 162 (or 162.28) constant come from?+
It is derived from the density of steel (7850 kg/m³) and the area of a circular bar. Weight per metre = (π/4) × (d/1000)² × 7850. Simplifying gives weight (kg/m) = d² ÷ 162.28, with d in mm. Many site engineers round the divisor to 162 for quick mental maths; this tool uses the more precise 162.28.
What is the unit weight of common rebar sizes?+
Using d²/162.28: 8 mm ≈ 0.394 kg/m, 10 mm ≈ 0.616 kg/m, 12 mm ≈ 0.888 kg/m, 16 mm ≈ 1.578 kg/m, 20 mm ≈ 2.465 kg/m, 25 mm ≈ 3.852 kg/m and 32 mm ≈ 6.310 kg/m. Multiply by the 12 m stock length to get the weight of one full bar.
How many bars are in one tonne of steel?+
Divide 1000 kg by the weight of one bar. A 12 m, 12 mm bar weighs about 10.66 kg, so roughly 94 bars make a tonne. A 12 m, 16 mm bar weighs about 18.93 kg, so about 53 bars make a tonne.
Why is the delivered weight sometimes different from the calculated weight?+
The d²/162.28 figure is a nominal (theoretical) weight. Rolled bars carry a manufacturing tolerance — IS 1786 (the TMT bar standard) allows the mass per metre to vary by a few percent. Cutting waste, laps and bends also add to the steel you actually buy, so order a small margin above the calculated figure.
Does this work for the foot or inch sizes sold in Nepal?+
The formula needs the diameter in millimetres and length in metres. If a bar is quoted in feet, convert it (1 ft = 0.3048 m) before entering the length. Common Nepali rebar diameters already use millimetres (8, 10, 12, 16, 20, 25, 32 mm), so the presets cover most jobs.
Sources & data note
Based on the standard unit-weight relation for round steel bars, weight (kg/m) = d² ÷ 162.28, derived from a steel density of 7850 kg/m³. Nominal (theoretical) weights are shown; rolled bars carry a manufacturing tolerance under IS 1786, and cutting waste, laps and bends add to the steel actually purchased. Bundle counts assume the 12 m stock length common in Nepal. These figures are indicative — verify current bar sizes, stock lengths and the Rs/kg rate with your supplier.