M Shapes (Miscellaneous Beams): Sizes & Weights
Light doubly symmetric beams that don’t fit the W or S series — common in light framing and misc. metals. 16 sizes from the AISC catalog, in lb/ft with kg/m alongside. Deeper reading: AISC Shape Database Guide.
M3 series
| Designation | lb/ft | kg/m | Area (in²) |
|---|---|---|---|
| M3X2.9 | 2.9 | 4.3 | 0.85 |
M5 series
| Designation | lb/ft | kg/m | Area (in²) |
|---|---|---|---|
| M5X18.9 | 18.9 | 28.1 | 5.55 |
M12.5 series
| Designation | lb/ft | kg/m | Area (in²) |
|---|---|---|---|
| M12.5X11.6 | 11.6 | 17.3 | 3.41 |
| M12.5X12.4 | 12.4 | 18.5 | 3.64 |
Areas marked as computed on the individual size pages are derived from the tabulated weight and steel density rather than read from the section table.
Need counts, not just sizes?
Upload a drawing set and SteelFlo puts a box on every steel label it finds — every miscellaneous (M) beam on every page — ready to review and export as a bill of materials.
3 free takeoffsNo credit card requiredAISC + 5 international standards