Steel Beam Dimensions
Universal Beams (UB) are I-shaped structural steel sections optimised for bending — the majority of the material sits in the top and bottom flanges, as far from the neutral axis as possible, where it does the most work resisting bending moment, while the thinner web mainly carries shear. UBs are the standard choice for floor beams, roof beams, and long-span members throughout general structural steelwork. The chart below gives dimensional and section property information for standard UB sizes, including depth, width, web and flange thickness, mass per metre, and second moment of area.
A UB's designation (e.g. 457x191x67 UB) states its serial depth, serial width, and mass per metre in that order — note that for a given serial size, the actual depth and width vary slightly between mass variants, since extra material is added to the web and flanges (rather than the overall depth) to increase capacity within the same nominal serial size.
The charts below gives the dimensions for Beam to BS 5950-1:2000.
Dimensions shown are in mm, if you wish to convert to Inches, please use our universal converter.
If you are interested in different sections why not try these?
- Steel CHS Dimensions
- Steel NB Pipe Dimensions
- Steel PFC Dimensions
- Steel RHS Dimensions
- Steel RSA Dimensions
- Steel SHS Dimensions
BEAM - BS 5950- 1:2000
| Section Designation | Mass per Metre | Depth of Section | Width of Section | Thickness | Root Radius | Depth between Fillets | Ratios for Local Buckling | Second Moment of Area | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Web | Flange | Flange | Web | Axis | Axis | ||||||
| D | B | t | T | r | d | b/T | d/t | x-x | y-y | ||
| kg/m | mm | mm | mm | mm | mm | mm | cm4 | cm4 | |||
| 203 x 203 x 45 | 44.9 | 200.2 | 205.9 | 9.5 | 9.5 | 10.2 | 160.8 | 10.8 | 16.9 | 4100 | 1384 |
| 203 x 203 x 54 | 53.9 | 204 | 207.7 | 11.3 | 11.4 | 10.2 | 160.8 | 9.11 | 14.2 | 5027 | 1705 |
| 254 x 254 x 63 | 63 | 247.1 | 256.6 | 10.6 | 10.7 | 12.7 | 200.3 | 12 | 18.9 | 8860 | 3016 |
| 254 x 254 x 71 | 71 | 249.7 | 258 | 12 | 12 | 12.7 | 200.3 | 10.8 | 16.7 | 10071 | 3439 |
| 254 x 254 x 85 | 85.1 | 254.3 | 260.4 | 14.4 | 14.3 | 12.7 | 200.3 | 9.1 | 13.9 | 12284 | 4215 |
| 305 x 305 x 110 | 110 | 307.9 | 310.7 | 15.3 | 15.4 | 15.2 | 246.7 | 10.1 | 16.1 | 23563 | 7709 |
| 305 x 305 x 126 | 126.1 | 312.3 | 312.9 | 17.5 | 17.6 | 15.2 | 246.7 | 8.89 | 14.1 | 27408 | 9002 |
| 305 x 305 x 149 | 149.1 | 318.5 | 316 | 20.6 | 20.7 | 15.2 | 246.7 | 7.63 | 12 | 33067 | 10910 |
| 305 x 305 x 186 | 186 | 328.3 | 320.9 | 25.5 | 25.6 | 15.2 | 246.7 | 6.27 | 9.67 | 42610 | 14143 |
| 305 x 305 x 223 | 222.9 | 337.9 | 325.7 | 30.3 | 30.4 | 15.2 | 246.7 | 5.36 | 8.14 | 52699 | 17577 |
| 305 x 305 x 79 | 78.9 | 299.3 | 306.4 | 11 | 11.1 | 15.2 | 246.7 | 13.8 | 22.4 | 16444 | 5326 |
| 305 x 305 x 88 | 88 | 301.7 | 307.8 | 12.4 | 12.3 | 15.2 | 246.7 | 12.5 | 19.9 | 18425 | 5984 |
| 305 x 305 x 95 | 94.9 | 303.7 | 308.7 | 13.3 | 13.3 | 15.2 | 246.7 | 11.6 | 18.5 | 20045 | 6529 |
| 356 x 368 x 109 | 108.9 | 346.4 | 371 | 12.8 | 12.9 | 15.2 | 290.2 | 14.4 | 22.7 | 30632 | 10987 |
| 356 x 368 x 133 | 133 | 352 | 373.8 | 15.6 | 15.7 | 15.2 | 290.2 | 11.9 | 18.6 | 37983 | 13680 |
| 356 x 368 x 152 | 152 | 356.4 | 376 | 17.8 | 17.9 | 15.2 | 290.2 | 10.5 | 16.3 | 43972 | 15877 |
| 356 x 368 x 174 | 173.9 | 361.4 | 378.5 | 20.3 | 20.4 | 15.2 | 290.2 | 9.28 | 14.3 | 51009 | 18463 |
| Section Designation | Radius of Gyration | Elastic Modulus | Plastic Modulus | Buckling Parameter | Torsional Index | Warping Constant | Torsional Constant | Area of Section | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Axis | Axis | Axis | Axis | Axis | Axis | ||||||
| x-x | y-y | x-x | y-y | x-x | y-y | u | x | H | J | A | |
| cm | cm | cm3 | cm3 | cm3 | cm3 | dm6 | cm4 | cm2 | |||
| 203 x 203 x 45 | 8.46 | 4.92 | 410 | 134 | 459 | 206 | 0.827 | 18.6 | 0.126 | 19.2 | 57.2 |
| 203 x 203 x 54 | 8.55 | 4.98 | 493 | 164 | 566 | 252 | 0.827 | 15.8 | 0.158 | 32.7 | 68.7 |
| 254 x 254 x 63 | 10.5 | 6.13 | 717 | 235 | 799 | 360 | 0.827 | 20.5 | 0.421 | 34.3 | 80.2 |
| 254 x 254 x 71 | 10.6 | 6.17 | 807 | 267 | 904 | 90.4 | 0.826 | 18.4 | 0.486 | 48.4 | 90.4 |
| 254 x 254 x 85 | 10.6 | 6.24 | 966 | 324 | 1092 | 498 | 0.825 | 15.6 | 0.607 | 81.8 | 108 |
| 305 x 305 x 110 | 13 | 7.42 | 496 | 1720 | 762 | 0.83 | 17.7 | 1.65 | 122 | 140 | |
| 305 x 305 x 126 | 13.1 | 7.49 | 1755 | 575 | 1986 | 885 | 0.829 | 15.7 | 1.95 | 182 | 161 |
| 305 x 305 x 149 | 13.2 | 7.58 | 2076 | 691 | 2370 | 1065 | 0.828 | 13.5 | 2.42 | 295 | 190 |
| 305 x 305 x 186 | 13.4 | 7.73 | 2596 | 881 | 3003 | 1366 | 0.827 | 11.1 | 3.24 | 560 | 237 |
| 305 x 305 x 223 | 13.6 | 7.87 | 3119 | 1079 | 3653 | 1680 | 0.826 | 9.55 | 4.15 | 943 | 284 |
| 305 x 305 x 79 | 12.8 | 7.28 | 1099 | 348 | 1218 | 531 | 0.832 | 23.9 | 1.11 | 46.9 | 100 |
| 305 x 305 x 88 | 12.8 | 7.31 | 1221 | 389 | 1361 | 595 | 0.83 | 21.6 | 1.25 | 64.2 | 112 |
| 305 x 305 x 95 | 12.9 | 7.35 | 1320 | 423 | 1475 | 648 | 0.83 | 20.2 | 1.38 | 80 | 121 |
| 356 x 368 x 109 | 14.9 | 8.9 | 1769 | 592 | 1956 | 903 | 0.823 | 24.2 | 3.05 | 84.6 | 139 |
| 356 x 368 x 133 | 15 | 8.99 | 2158 | 732 | 2406 | 1118 | 0.822 | 20.1 | 3.87 | 151 | 169 |
| 356 x 368 x 152 | 15.1 | 9.05 | 2468 | 845 | 2761 | 1293 | 0.821 | 17.8 | 4.55 | 223 | 194 |
| 356 x 368 x 174 | 15.2 | 9.13 | 2823 | 976 | 3186 | 1497 | 0.821 | 15.8 | 5.37 | 330 | 221 |
RELATED PAGES
- Steel PFC Dimensional Information
- Steel SHS Dimensional Information
- Steel Rolled Steel Angle Dimensions
FREQUENTLY ASKED QUESTIONS
What's the difference between a Universal Beam (UB) and Universal Column (UC)?
A UB has a narrower flange relative to its depth, optimised for bending resistance in one direction, typical of a beam spanning between supports. A UC has a near-square profile with roughly equal depth and width, giving similar stiffness about both axes, which suits a column that may need to resist buckling or load from more than one direction.
Why do heavier beams of the same serial size have slightly different dimensions?
Extra mass within the same serial size is usually added by thickening the web and flanges rather than changing the overall depth and width significantly, so a heavier variant of the same serial size will be marginally larger overall as well as having thicker material, giving greater strength and stiffness.
Should I choose a UB based on depth alone?
No — depth is a useful starting guide, but the actual choice should be based on a proper structural calculation considering the applied load, span, deflection limits, and lateral restraint conditions. Always verify with a qualified structural engineer for load-bearing applications.
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