Steel Weight Calculator
Calculate the weight of steel reinforcement bars from diameter, length and quantity using the d²/162 formula.
Formula last reviewed 4 August 2026 · How we verify our calculators
Total steel weight
53.33 kg
- Weight per metre
- 0.889 kg/m
Updates live as you type
Frequently asked questions
It is the standard way to find the weight of a steel bar per metre: weight (kg/m) = diameter² ÷ 162, with the diameter in millimetres. A 12 mm bar weighs about 0.888 kg/m.
It is derived from steel’s density (7,850 kg/m³) and the area formula, simplified into the constant 162 for convenience when the diameter is in mm and length in metres.
Multiply the per-metre weight by the length of each bar and the number of bars. Ten 12 mm bars of 6 m each weigh about 53.3 kg.
Yes, for round TMT/rebar of any diameter — 8, 10, 12, 16, 20, 25 mm and so on. Just enter the nominal diameter in millimetres.
Fifty-three kilos of twelve-mil bar
Ten lengths of 12 mm reinforcement bar, each 6 m long, weigh 53.33 kg — 0.889 kg per metre.
Steel is specified by diameter and ordered by weight, so converting between the two is the routine arithmetic of any reinforced concrete job.
The formula every site uses
Weight per metre (kg/m) = d² ÷ 162, where d is the bar diameter in millimetres.
For 12 mm: 12² ÷ 162 = 144 ÷ 162 = 0.889 kg/m.
Total weight = weight per metre × length × quantity = 0.889 × 6 × 10 = 53.33 kg.
The 162 is not arbitrary. Steel has a density of 7,850 kg/m³, and the cross-sectional area of a round bar is πd²/4. Working through with d in millimetres and converting units gives a divisor of 1,000,000 × 4 ÷ (π × 7,850) ≈ 162.28, universally rounded to 162 on site.
Standard bar weights
Worth memorising, because they come up constantly:
- 8 mm — 0.395 kg/m
- 10 mm — 0.617 kg/m
- 12 mm — 0.889 kg/m
- 16 mm — 1.580 kg/m
- 20 mm — 2.469 kg/m
- 25 mm — 3.858 kg/m
- 32 mm — 6.321 kg/m
Note the relationship is quadratic: a 16 mm bar is not twice a 8 mm bar, it is four times the weight, because area scales with the square of diameter. This is why stepping up one bar size adds considerably more steel — and cost — than it appears to.
Grades
Indian reinforcement is specified as Fe 415, Fe 500 and Fe 550, where the number is the yield strength in N/mm². Fe 500 is the general standard for residential and commercial work.
The D suffix — Fe 500D — indicates enhanced ductility, with tighter limits on elongation and the ratio of ultimate to yield strength. It is preferred in seismic zones, which covers most of India under IS 1893, and is worth specifying rather than accepting whatever is delivered.
CRS (corrosion-resistant steel) grades carry a small premium and are worth considering in coastal and high-humidity environments where chloride ingress is a genuine risk.
Ordering and cutting
Standard bar length in India is 12 m, sometimes supplied at 6 m. A bar bending schedule — the list of every bar's shape, length and count — is what allows efficient cutting, and a good schedule reduces offcut wastage from perhaps 5% to under 2% on a large job.
Add roughly 3–5% to the calculated weight for laps, offcuts and binding wire. Lap lengths themselves are substantial — typically 50 times the bar diameter for tension laps — and on a job with many splices this is not a rounding error but a real quantity.
Reading the result
The weight is exact for the nominal diameter. Actual delivered bars carry a rolling tolerance — IS 1786 permits a few percent variation in mass per metre, tighter for larger diameters. On a large order this matters, and steel is weighed on delivery rather than counted.
Note also the distinction between nominal and actual diameter on TMT bars: the ribs mean the outside dimension exceeds the nominal, and specifications always refer to the nominal.
Common mistakes
Using the diameter in centimetres or metres. The formula takes millimetres.
Forgetting laps. They can add several percent to the total on a splice-heavy job.
Assuming weight scales linearly with diameter. It scales with the square.
Accepting Fe 500 where Fe 500D is specified. The ductility difference matters in seismic design.
Counting bars without a bending schedule. Offcut wastage rises sharply without one.