UB 533×210×92 vs W 21X62
UB 533×210×92 is an UB section from the UK Blue Book (SCI P363); W 21X62 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 2360 cm³ against 2359.7 cm³ of plastic modulus, a difference of 0.0%. They weigh essentially the same, 92.1 kg/m and 92.3 kg/m. Both are about 533 mm deep, so either fits the same construction zone.
| Property | UB 533×210×92 UB | W 21X62 W | Difference |
|---|---|---|---|
| Mass | 92.1 kg/m | 92.3 kg/m | -0.2% |
| Depth | 533.1 mm | 533.4 mm | -0.1% |
| Width | 209.3 mm | 209.3 mm | same |
| Web thickness | 10.1 mm | 10.2 mm | -1.0% |
| Flange thickness | 15.6 mm | 15.6 mm | same |
| Area | 117 cm² | 118.1 cm² | -0.9% |
| Second moment, major (Iy) | 55,200 cm⁴ | 55,359 cm⁴ | -0.3% |
| Plastic modulus, major (Wpl,y) | 2,360 cm³ | 2,359.7 cm³ | same |
| Elastic modulus, major (Wel,y) | 2,070 cm³ | 2,081.2 cm³ | -0.5% |
| Second moment, minor (Iz) | 2,390 cm⁴ | 2,393 cm⁴ | -0.1% |
| Plastic modulus, minor (Wpl,z) | 355 cm³ | 355.6 cm³ | -0.2% |
| Radius of gyration, minor (iz) | 4.51 cm | 4.5 cm | +0.2% |
| Torsion constant (It) | 75.7 cm⁴ | 76.17 cm⁴ | -0.6% |
UB 533×210×92 to BS EN 10365:2017; W 21X62 to AISC Shapes Database v16.0. Difference is expressed relative to W 21X62.
How to choose between them
On stiffness, W 21X62 has the larger second moment of area: 55,359 cm⁴ against 55,200 cm⁴, a difference of 0.3%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram, the two are equally efficient (25.6 against 25.6 cm³ per kg/m), so on a pure steel-tonnage basis there is nothing to choose between them. The decision comes down to availability, connection detailing and what the rest of the frame uses.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. UB sections are specified to BS EN 10365:2017 and W to AISC Shapes Database v16.0; the steel grades, tolerances and available lengths differ, connection details and bolt gauges are set out differently, and the two are rarely both stocked in the same market. Check availability before changing a section on a drawing to save a marginal amount of weight.
In short, these two are genuine equivalents. Pick whichever your supplier stocks and the rest of the frame already uses.