Junior beams
M-shapes are lightweight miscellaneous beams that do not fit the W, S, or HP classifications. Typically used for light framing and infill.
All 16 junior beams in the AISC Shapes Database, 16th Edition, with detailing dimensions and section properties drawn to scale.
Open the interactive size chart →All 16 junior beams
M3×2.9M6×3.7M4×4.08M6×4.4M4×6M8×6.2M8×6.5M10×7.5M10×8M10×9M12×10M12×10.8M12.5×11.6M12×11.8M12.5×12.4M5×18.9
Junior beams weight and dimension chart
All 16 junior beams by weight, with depth, width, and section modulus. Click any size for its full detail.
| Size | Weight (lb/ft) | Depth | Flange | Sx (in³) |
|---|---|---|---|---|
| M3×2.9 | 2.9 | 3" | 2 1/4" | 1 |
| M6×3.7 | 3.7 | 5 7/8" | 2" | 2.01 |
| M4×4.08 | 4.08 | 4" | 2 1/4" | 1.77 |
| M6×4.4 | 4.4 | 6" | 1 7/8" | 2.41 |
| M4×6 | 6 | 3 3/4" | 3 3/4" | 2.48 |
| M8×6.2 | 6.2 | 8" | 2 1/4" | 4.39 |
| M8×6.5 | 6.5 | 8" | 2 1/4" | 4.63 |
| M10×7.5 | 7.5 | 10" | 2 3/4" | 6.6 |
| M10×8 | 8 | 10" | 2 3/4" | 6.95 |
| M10×9 | 9 | 10" | 2 3/4" | 7.79 |
| M12×10 | 10 | 12" | 3 1/4" | 10.3 |
| M12×10.8 | 10.8 | 12" | 3 1/8" | 11.1 |
| M12.5×11.6 | 11.6 | 12 1/2" | 3 1/2" | 12.8 |
| M12×11.8 | 11.8 | 12" | 3 1/8" | 12 |
| M12.5×12.4 | 12.4 | 12 1/2" | 3 3/4" | 14.2 |
| M5×18.9 | 18.9 | 5" | 5" | 9.67 |
Data from the AISC Shapes Database v16.0. Detailing values are rounded to the nearest 1/16 in.; verify critical dimensions against the current AISC Steel Construction Manual before fabrication.