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Steel Weight Calculator

Free, instant weight calculation for every Indian standard steel section. Add multiple items, get per-piece and total weights, export to CSV. Built on official IS 808 and IS 1786 weight tables for ISMB, ISHB, ISMC, ISA and TMT rebar — with formulas for plates, rounds, squares, flats, hex bar and pipes calculated at mild steel density 7,850 kg/m³.

Per IS 808 & IS 1786
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Calculate steel weight

Material: Mild Steel · Density 7,850 kg/m³
Total Pieces
0
Total Weight (kg)
0.00 kg
Total Weight (tonnes)
0.000 t

How steel weight is calculated

Steel weight depends on two things: the cross-sectional area of the section and its length. Multiply that volume by the density of the material and you get mass. For mild steel, the density used in every Indian standard (IS 808, IS 1786, IS 2062) is 7,850 kg/m³ — equivalent to 7.85 g/cm³.

For standard rolled sections (ISMB, ISHB, ISMC, ISA, TMT rebar), the weight per metre is published directly in the IS 808 and IS 1786 tables. This calculator uses those official values, so the result for a rolled section is simply weight per metre × length × quantity. No assumption or approximation involved.

For raw geometric shapes (round bar, square bar, flat bar, plate, hex bar, pipe), the calculator computes the cross-sectional area from your dimensions and multiplies by length and density. The formulas are standard and accurate to within rolling tolerance:

Round bar: π / 4 × D² × L × 7.85 / 1000 = kg
Square bar: A² × L × 7.85 / 1000 = kg
Flat bar: W × T × L × 7.85 / 1000 = kg
Plate / sheet: L × W × T × 7.85 = kg (L, W in m; T in mm)
Hex bar: 0.866 × A² × L × 7.85 / 1000 = kg
Pipe: π × (OD − T) × T × L × 7.85 / 1000 = kg

Where D = diameter (mm), A = side (mm), W = width (mm), T = thickness or wall thickness (mm), L = length (m), OD = outer diameter (mm). Constants 7.85 represent mild steel density expressed for the relevant unit conversion.

Material density — why 7,850 kg/m³

Mild steel is approximately 98% iron with carbon content under 0.25% and trace amounts of manganese, silicon, phosphorus and sulphur. The density of pure iron is 7,874 kg/m³, and the small amount of carbon and other elements brings the average density of typical mild steel to 7,850 kg/m³. This is the value formally adopted by the Bureau of Indian Standards for all weight calculations of structural sections, rebar and plate.

Other common metals for reference:

MaterialDensity (kg/m³)Use
Mild steel (IS 2062)7,850This calculator. Default for ISMB, ISHB, ISMC, ISA, TMT, plates
Stainless steel 3048,000Food, chemical, decorative
Stainless steel 3168,000Marine, pharmaceutical
Cast iron7,200Engine blocks, manhole covers
Aluminium 60612,700Aerospace, automotive panels
Brass8,500Plumbing, decorative, fittings
Copper8,960Electrical conductors, tubing
Lead11,340Radiation shielding, batteries

If you need to calculate weight for a non-mild-steel material, multiply the result from this calculator by the ratio of your material's density to 7,850. For example, for stainless steel 304: kgSS = kgMS × (8,000 / 7,850) = kgMS × 1.019.

Standard weights per metre — quick reference

The values below are taken directly from IS 808:1989 (rolled sections) and IS 1786:2008 (TMT rebar). They are the same values used inside this calculator.

TMT Rebar (IS 1786)

DiameterWeight per metrePieces per tonne (12 m bars)
6 mm0.222 kg/m~375
8 mm0.395 kg/m~211
10 mm0.617 kg/m~135
12 mm0.888 kg/m~94
16 mm1.580 kg/m~53
20 mm2.466 kg/m~34
25 mm3.854 kg/m~22
28 mm4.834 kg/m~17
32 mm6.313 kg/m~13
36 mm7.990 kg/m~10
40 mm9.864 kg/m~8

ISMB I-Beams (IS 808)

DesignationDepthWeight per metreMetres per tonne
ISMB 100100 mm11.5 kg/m~87
ISMB 125125 mm13.0 kg/m~77
ISMB 150150 mm14.9 kg/m~67
ISMB 175175 mm19.3 kg/m~52
ISMB 200200 mm25.4 kg/m~39
ISMB 225225 mm31.2 kg/m~32
ISMB 250250 mm37.3 kg/m~27
ISMB 300300 mm44.2 kg/m~23
ISMB 350350 mm52.4 kg/m~19
ISMB 400400 mm61.5 kg/m~16
ISMB 450450 mm72.4 kg/m~14
ISMB 500500 mm86.9 kg/m~12
ISMB 550550 mm103.7 kg/m~10
ISMB 600600 mm122.6 kg/m~8

Full ISMB profile data with sectional properties: View all I-beams

Frequently asked questions

How accurate is this calculator?
For standard rolled sections (ISMB, ISHB, ISMC, ISA, TMT) the values come straight from IS 808 and IS 1786 published tables, so the calculation is exact — subject only to rolling tolerances on the actual delivered material (typically ±2.5% per IS 1852). For raw shapes (round, square, flat, plate, hex, pipe), the formulas use mild steel density of 7,850 kg/m³ and pure geometry, accurate to four significant figures. Real material may vary by ±1–3% depending on supplier tolerances, surface scaling and dimensional variation.
Why does my supplier’s invoice show a different weight than this calculator?
A few common reasons: (1) Indian steel rebar is often sold by “nominal weight” per IS 1786, but actual weight can be slightly under tolerance (within −3.5% for sizes up to 16 mm and −3% above) — some suppliers will quote actual rolled weight. (2) Plate suppliers sometimes round up to the next thickness for invoicing. (3) Hot rolled sections include mill scale which adds 0.5–1% weight when fresh. (4) Cut-to-length operations may have an offcut allowance built in. Always cross-check by physical weighbridge for orders above 5 tonnes.
Can I use this for stainless steel or aluminium?
This calculator is fixed at mild steel density (7,850 kg/m³) for v1. To get the weight for another material, calculate it here for mild steel and then multiply by the density ratio: stainless 304 = ×1.019, aluminium = ×0.344, brass = ×1.083, copper = ×1.141. We may add a material dropdown in a future update — let us know on the feedback page if this is something you need.
Why does TMT 8 mm weigh 0.395 kg/m and not what I calculated from πr² × density?
TMT bar has rolled-on ribs that increase the actual cross-section above the nominal diameter, but IS 1786 specifies a “nominal mass” that’s used for selling and weighing. For 8 mm bar, π/4 × 8² × 7.85 / 1000 = 0.394 kg/m, which matches the IS 1786 nominal value of 0.395 kg/m almost exactly. The IS standard rounds these and bakes them into Table 1. We use the IS values directly so you get an answer that matches your supplier’s invoice.
Does this work offline?
Once the page has loaded once, all calculations happen in your browser with no network calls. You can use it without an internet connection for the rest of the session. We may add a downloadable offline version in a future update.
Can I save my calculations?
Yes — click Export CSV to download your entire calculation as a spreadsheet you can open in Excel, Google Sheets, or any text editor. Use Print to save as PDF (use your browser’s "Print to PDF" option). Use Copy results to paste a plain-text summary into an email, WhatsApp message, or Word document.
Is this calculator free for commercial use?
Yes. Use it for your projects, quotations, BOQs and material take-offs without restriction. We don’t collect any data, don’t require signup, and don’t track inputs. If you find an error or want to request a new section type, please let us know.
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