ISMC 75 weight and dimensions
7.14 kg/m · 4.80 lb/ft
ISMC 75 is a 75 mm deep channel with a 40 mm flange, 4.8 mm web and 7.5 mm flange thickness. It weighs 7.14 kg per metre (4.80 lb/ft). It belongs to the ISMC medium weight channel series, Indian Standard (IS 808).
Many weight charts list ISMC 75 as 6.8 kg/m. That figure comes from the 1964 ISI handbook. The current standard, IS 808:2021, gives 7.14 kg/m (IS 808:1989: 7.14 kg/m).
IS 808:2021 prints rz = 39.4 mm; sqrt(Izz / A) gives 29.4 mm, as in IS 808:1989.
ISMC 75 weight calculator
Weight of standard lengths
| Pieces | 6 m each (kg) | 12 m each (kg) |
|---|---|---|
| 1 | 42.8 | 85.7 |
| 5 | 214.2 | 428.4 |
| 10 | 428.4 | 856.8 |
| 20 | 856.8 | 1,713.6 |
| 50 | 2,142.0 | 4,284.0 |
Pieces per tonne
| 6 m lengths per metric tonne | 23.3 |
| 12 m lengths per metric tonne | 11.7 |
| Length per tonne | 140.1 m |
Useful for converting a tonnage order into a number of bars.
Surface area for painting
| Per metre of length | 0.293 m²/m |
| Per foot of length | 0.96 ft²/ft |
| Per tonne of steel | 41.1 m²/t |
| A 12 m length | 3.52 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 | 75 mm | 2.953 in |
| Flange width b | 40 mm | 1.575 in |
| Web thickness tw | 4.8 mm | 0.189 in |
| Flange thickness tf | 7.5 mm | 0.295 in |
| Root radius r | 8.5 mm | 0.335 in |
| Toe radius r2 | 2.4 mm | 0.094 in |
| Flange slope (deg) | 96° | |
| Mass | 7.14 kg/m | 4.80 lb/ft |
Section properties
| Property | Value | Unit |
|---|---|---|
| Area | 9.08 | cm² |
| Moment of inertia Ix | 78.20 | cm⁴ |
| Moment of inertia Iy | 12.70 | cm⁴ |
| Elastic modulus Zx | 20.90 | cm³ |
| Elastic modulus Zy | 4.80 | cm³ |
| Plastic modulus Zpx | 25.00 | cm³ |
| Plastic modulus Zpy | 9.00 | cm³ |
| Radius of gyration rx | 2.94 | cm |
| Radius of gyration ry | 1.18 | cm |
| Torsion constant J | 1.59 | 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.
ISMC 75 and its closest equivalents, drawn over each other at the same scale.
| Section | Standard | Depth (mm) | kg/m | Weight vs ISMC 75 |
|---|---|---|---|---|
| ISMC 75 | IS | 75 | 7.14 | — |
| UPN 65 | EN | 65 | 7.11 | -0.4% |
| UPN 80 | EN | 80 | 8.65 | +21.1% |
| C3x5 | AISC | 76.2 | 7.40 | +3.6% |
| C3x4.1 | AISC | 76.2 | 6.10 | -14.6% |
ISMC series weights
Next heavier: ISMC 100 (9.56 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 |
|---|---|---|---|---|
| ISMC 75 | 7.14 | 78 | 20.9 | 2.93 |
| ISMC 100 | 9.56 | 191 | 38.4 | 4.02 |
| ISMC 125 | 13.10 | 424 | 67.9 | 5.18 |
| ISMC 150 | 16.80 | 786 | 104.0 | 6.19 |
Full table: ISMC channel weight chart (PDF).
How the weight is calculated
Mass per metre = cross-sectional area × density of steel = 9.08 cm² × 0.785 kg/(cm²·m) = 7.13 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
Channels are used as purlins, girts, stair stringers, trimmers, frames and bracing, and back to back as built-up columns.
Frequently asked questions
What is the weight of ISMC 75 per metre?
ISMC 75 weighs 7.14 kg/m, which is 4.80 lb/ft.
How much does a 6 m or 12 m length of ISMC 75 weigh?
A 6 m length weighs about 42.8 kg and a 12 m length about 85.7 kg.
Why do some weight charts show 6.8 kg/m for ISMC 75?
6.8 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 7.14 kg/m. Many charts still copy the old figure, so confirm which standard your supplier rolls to.
What is the equivalent of ISMC 75 in other standards?
By depth and weight the closest match is UPN 65 (7.11 kg/m, 65 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.