W 21X147 vs H-600x300x16x27
W 21X147 is an W section from the American AISC Shapes Database; H-600x300x16x27 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 6112.4 cm³ against 6101 cm³ of plastic modulus, a difference of 0.2%. H-600x300x16x27 is the lighter of the two at 203 kg/m against 218.8 kg/m, a saving of 7.8% on steel weight. H-600x300x16x27 is deeper, 602 mm against 561.3 mm, which matters where the floor zone is tight.
| Property | W 21X147 W | H-600x300x16x27 MB & MC | Difference |
|---|---|---|---|
| Mass | 218.8 kg/m | 203 kg/m | +7.8% |
| Depth | 561.3 mm | 602 mm | -6.8% |
| Width | 317.5 mm | 304 mm | +4.4% |
| Web thickness | 18.3 mm | 16 mm | +14.4% |
| Flange thickness | 29.2 mm | 27 mm | +8.1% |
| Area | 278.7 cm² | 259 cm² | +7.6% |
| Second moment, major (Iy) | 151,092 cm⁴ | 162,600 cm⁴ | -7.1% |
| Plastic modulus, major (Wpl,y) | 6,112.4 cm³ | 6,101 cm³ | +0.2% |
| Elastic modulus, major (Wel,y) | 5,391.3 cm³ | 5,401 cm³ | -0.2% |
| Second moment, minor (Iz) | 15,650 cm⁴ | 12,680 cm⁴ | +23.4% |
| Plastic modulus, minor (Wpl,z) | 1,517.4 cm³ | 1,292 cm³ | +17.4% |
| Radius of gyration, minor (iz) | 7.49 cm | 7 cm | +7.0% |
| Torsion constant (It) | 641 cm⁴ | 551 cm⁴ | +16.3% |
W 21X147 to AISC Shapes Database v16.0; H-600x300x16x27 to Continental Steel. Difference is expressed relative to H-600x300x16x27.
How to choose between them
On stiffness, H-600x300x16x27 has the larger second moment of area: 162,600 cm⁴ against 151,092 cm⁴, a difference of 7.1%. 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 of steel, H-600x300x16x27 is the more efficient section: 30.1 against 27.9 cm³ per kg/m, 7.0% better. Over a floor of repeated beams that difference is real tonnage, though it is often outweighed by whichever section the fabricator can actually source.
The two diverge much more about the minor axis: W 21X147 has 1517.4 cm³ of minor-axis plastic modulus against 1292 cm³, 17.4% more. If the member sees any minor-axis bending, or if it is unrestrained over a long length and lateral-torsional buckling governs, that gap decides the comparison even though the major-axis numbers looked equivalent.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. W sections are specified to AISC Shapes Database v16.0 and MB & MC to Continental Steel; 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 7.8% weight.
In short, W 21X147 is the stronger section and H-600x300x16x27 is the lighter one; where those are the same section, it is the clear choice, and where they are not, decide on whether your design is governed by capacity or by tonnage.