IPE 500 vs W 18X65
IPE 500 is an IPE section from the European (Continental) range; W 18X65 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 2190 cm³ against 2179.5 cm³ of plastic modulus, a difference of 0.5%. IPE 500 is the lighter of the two at 90.7 kg/m against 96.7 kg/m, a saving of 6.2% on steel weight. IPE 500 is deeper, 500 mm against 467.4 mm, which matters where the floor zone is tight.
| Property | IPE 500 IPE | W 18X65 W | Difference |
|---|---|---|---|
| Mass | 90.7 kg/m | 96.7 kg/m | -6.2% |
| Depth | 500 mm | 467.4 mm | +7.0% |
| Width | 200 mm | 192.8 mm | +3.7% |
| Web thickness | 10.2 mm | 11.4 mm | -10.5% |
| Flange thickness | 16 mm | 19 mm | -15.8% |
| Area | 116 cm² | 123.2 cm² | -5.8% |
| Second moment, major (Iy) | 48,200 cm⁴ | 44,537 cm⁴ | +8.2% |
| Plastic modulus, major (Wpl,y) | 2,190 cm³ | 2,179.5 cm³ | +0.5% |
| Elastic modulus, major (Wel,y) | 1,930 cm³ | 1,917.3 cm³ | +0.7% |
| Second moment, minor (Iz) | 2,140 cm⁴ | 2,281 cm⁴ | -6.2% |
| Plastic modulus, minor (Wpl,z) | 336 cm³ | 368.71 cm³ | -8.9% |
| Radius of gyration, minor (iz) | 4.31 cm | 4.29 cm | +0.5% |
| Torsion constant (It) | 89.1 cm⁴ | 113.6 cm⁴ | -21.6% |
IPE 500 to EN 10365 · Continental Steel; W 18X65 to AISC Shapes Database v16.0. Difference is expressed relative to W 18X65.
How to choose between them
On stiffness, IPE 500 has the larger second moment of area: 48,200 cm⁴ against 44,537 cm⁴, a difference of 8.2%. 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, IPE 500 is the more efficient section: 24.1 against 22.5 cm³ per kg/m, 7.1% 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 18X65 has 368.71 cm³ of minor-axis plastic modulus against 336 cm³, 8.9% 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. IPE sections are specified to EN 10365 · Continental Steel 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 6.2% weight.
In short, IPE 500 is the stronger section and IPE 500 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.