ISMB 300 weight and dimensions
46.02 kg/m · 30.92 lb/ft
ISMB 300 is a 300 mm deep beam with a 140 mm flange, 7.7 mm web and 13.1 mm flange thickness. It weighs 46.02 kg per metre (30.92 lb/ft). It belongs to the ISMB medium weight beam series, Indian Standard (IS 808).
Many weight charts list ISMB 300 as 44.2 kg/m. That figure comes from the 1964 ISI handbook. The current standard, IS 808:2021, gives 46.02 kg/m (IS 808:1989: 46 kg/m).
ISMB 300 weight calculator
Weight of standard lengths
| Pieces | 6 m each (kg) | 12 m each (kg) |
|---|---|---|
| 1 | 276.1 | 552.2 |
| 5 | 1,380.6 | 2,761.2 |
| 10 | 2,761.2 | 5,522.4 |
| 20 | 5,522.4 | 11,044.8 |
| 50 | 13,806.0 | 27,612.0 |
Pieces per tonne
| 6 m lengths per metric tonne | 3.6 |
| 12 m lengths per metric tonne | 1.8 |
| Length per tonne | 21.7 m |
Useful for converting a tonnage order into a number of bars.
Surface area for painting
| Per metre of length | 1.121 m²/m |
| Per foot of length | 3.68 ft²/ft |
| Per tonne of steel | 24.3 m²/t |
| A 12 m length | 13.45 m² |
Outside perimeter × length, all faces, calculated from the dimensions. Use it to estimate paint, primer, fireproofing or galvanizing quantities.
Cross-section
Drawn to scale. Dimensions in mm.
Dimensions
| Depth h | 300 mm | 11.811 in |
| Flange width b | 140 mm | 5.512 in |
| Web thickness tw | 7.7 mm | 0.303 in |
| Flange thickness tf | 13.1 mm | 0.516 in |
| Root radius r | 14 mm | 0.551 in |
| Toe radius r2 | 7 mm | 0.276 in |
| Flange slope (deg) | 98° | |
| Mass | 46.02 kg/m | 30.92 lb/ft |
Section properties
| Property | Value | Unit |
|---|---|---|
| Area | 58.60 | cm² |
| Moment of inertia Ix | 8,990 | cm⁴ |
| Moment of inertia Iy | 486 | cm⁴ |
| Elastic modulus Zx | 599 | cm³ |
| Elastic modulus Zy | 69.40 | cm³ |
| Plastic modulus Zpx | 681 | cm³ |
| Plastic modulus Zpy | 117 | cm³ |
| Radius of gyration rx | 12.30 | cm |
| Radius of gyration ry | 2.87 | cm |
| Torsion constant J | 34.70 | cm⁴ |
Equivalent sections in other standards
The closest sections by depth and weight. They are not direct substitutes: check bending, buckling and connection details before swapping one for another.
ISMB 300 and its closest equivalents, drawn over each other at the same scale.
| Section | Standard | Depth (mm) | kg/m | Weight vs ISMB 300 |
|---|---|---|---|---|
| ISMB 300 | IS | 300 | 46.02 | — |
| IPE 300 | EN | 300 | 42.24 | -8.2% |
| IPE 330 | EN | 330 | 49.15 | +6.8% |
| S12x31.8 | AISC | 305 | 47.30 | +2.8% |
| W12x30 | AISC | 312 | 44.50 | -3.3% |
ISMB series weights
Next lighter: ISMB 250 (37.3 kg/m). Next heavier: ISMB 350 (52.33 kg/m).
Stiffness and strength per kilogram
The elastic section modulus Zx governs bending strength. Dividing it by the weight shows how efficiently each size uses its steel: higher is better when weight is the cost driver.
| Section | kg/m | Ix (cm⁴) | Zx (cm³) | Zx per kg/m |
|---|---|---|---|---|
| ISMB 200 | 24.17 | 2,110 | 211.0 | 8.73 |
| ISMB 225 | 31.15 | 3,440 | 306.0 | 9.82 |
| ISMB 250 | 37.30 | 5,130 | 410.0 | 10.99 |
| ISMB 300 | 46.02 | 8,990 | 599.0 | 13.02 |
| ISMB 350 | 52.33 | 13,600 | 779.0 | 14.89 |
| ISMB 400 | 61.55 | 20,400 | 1,020.0 | 16.57 |
| ISMB 450 | 72.38 | 30,400 | 1,350.0 | 18.65 |
Full table: ISMB weight chart (PDF).
How the weight is calculated
Mass per metre = cross-sectional area × density of steel = 58.60 cm² × 0.785 kg/(cm²·m) = 46.00 kg/m.
Rolled sections are made to a nominal mass, and the actual mass can differ by a few percent within the tolerances of IS 1852. For purchasing, invoicing by weight or checking deliveries, use the producer's stated mass.
Typical uses
Beams of this shape are used as floor and roof beams, lintels, crane girders and frame members, where bending about the strong axis governs.
Frequently asked questions
What is the weight of ISMB 300 per metre?
ISMB 300 weighs 46.02 kg/m, which is 30.92 lb/ft.
How much does a 6 m or 12 m length of ISMB 300 weigh?
A 6 m length weighs about 276.1 kg and a 12 m length about 552.2 kg.
Why do some weight charts show 44.2 kg/m for ISMB 300?
44.2 kg/m is the value in the 1964 ISI handbook SP 6(1). IS 808 was revised in 1989 and the section dimensions changed; IS 808:2021 gives 46.02 kg/m. Many charts still copy the old figure, so confirm which standard your supplier rolls to.
What is the equivalent of ISMB 300 in other standards?
By depth and weight the closest match is IPE 300 (42.24 kg/m, 300 mm deep). Check section properties before substituting one for the other.
Source: IS 808:2021; earlier values from IS 808:1989 and SP 6(1):1964. Values are nominal; verify with the producer before ordering.