a 12 mm bar is 0.888 kg/m
- Bar diameter (mm)
- 12
- Total length (m)
- 1
- Number of bars
- 1
Total weight (kg)0.89
DRV-018: 7850 x pi x 144 / 4 / 1e6, independently computed
Open this exampleConstruction & HomematerialsIndia only
Steel / Rebar Weight Calculator
Reinforcement steel weight from bar diameter and length, with the exact figure alongside the familiar d²/162 shortcut. The exact denominator is 162.196.
Also called: rebar weight calculator, tmt bar weight.
Total weight (kg)
88.78
88.78 kg. A 12 mm bar weighs 0.8878 kg per metre, which is where the d²/162 rule comes from.
Weight per metre (kg)
0.8878
The d²/162 shortcut
0.8889
Total weight (tonnes)
0.0888
Method and background
How this is calculated
Mass is density times cross-sectional area times length. Putting in 7850 kg/m³ and πd²/4 with the millimetre-to-metre conversion collapses everything except d² into a single constant, 162.196, universally rounded to 162. Every Indian site quotes the shortcut; almost none derives it, and two lines of algebra is the difference between a number you trust and one you look up.
weight_per_m = 7850 * pi * d^2 / 4 * 1e-6 = d^2 / 162.196- d
- Bar diameter in millimetres (mm)
- density
- Steel density, 7850 kg/m³ (kg/m3)
Full derivation: Why steel weight is d² ÷ 162
Worked examples
Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.
the shortcut is close but not exact
- Bar diameter (mm)
- 12
- Total length (m)
- 1
- Number of bars
- 1
Total weight (kg)0.89
DRV-018: 144/162 against an exact denominator of 162.196
Open this example100 bars of 16 mm at 12 m
- Bar diameter (mm)
- 16
- Total length (m)
- 12
- Number of bars
- 100
Total weight (kg)1,894
independently computed: 1.5783 kg/m x 1200 m
Open this exampleMethod and limits
What it assumes
- Steel density 7850 kg/m³, the standard value for mild and TMT reinforcement.
Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator