W30x99 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W30x99 is an American wide-flange beam 29.7 inches (754.4 mm) deep with a 10.5 in (266.7 mm) flange, weighing 99 pounds per foot (147.3 kg/m) — that is what the "99" in the designation means. All values below are the standard AISC published section properties used in US structural design, with metric equivalents alongside.
Typical uses: floor and roof framing, columns, headers, and general steel construction. For a quick stiffness check, see the deflection example below or open the beam calculator with your own span and load.
Dimensions
| Depth d | 29.7 in (754.4 mm) |
| Flange width bf | 10.5 in (266.7 mm) |
| Web thickness tw | 0.52 in (13.2 mm) |
| Flange thickness tf | 0.67 in (17 mm) |
Weight & Cross-Section
| Weight per foot | 99 lb/ft (147.3 kg/m) |
| 20 ft bar | 1,980 lb |
| 40 ft bar | 3,960 lb |
| Area A | 29 in² (187.1 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 3,990 in⁴ (166,076 cm⁴) |
| Section modulus Sx | 269 in³ (4,408 cm³) |
| Radius of gyration rx | 11.7 in |
| Moment of inertia Iy | 128 in⁴ (5,328 cm⁴) |
| Section modulus Sy | 24.5 in³ (401 cm³) |
| Radius of gyration ry | 2.1 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W30x90 | 29.5 × 10.4 | 90 | 3,610 | 245 | −9 % | −10 % |
| W30x99 (this page) | 29.7 × 10.5 | 99 | 3,990 | 269 | — | — |
| W30x108 | 29.8 × 10.5 | 108 | 4,470 | 299 | +9 % | +12 % |
Deflection example
A simply supported W30x99 spanning 48 ft with a 10 kip point load at midspan deflects 0.34 in (E = 29,000 ksi, Ix = 3,990 in⁴). The L/360 serviceability limit for this span is 1.6 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W30x99 beam weigh?
W30x99 weighs 99 pounds per foot (147.3 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 1,980 lb and a 40 ft bar 3,960 lb.
What are the dimensions of a W30x99?
W30x99 is 29.7 in (754.4 mm) deep with a 10.5 in (266.7 mm) wide flange. The web is 0.52 in thick and the flanges are 0.67 in thick. Note the actual depth differs from the nominal W30 label — always design with the actual value.
What are the dimensions of a W30x99 in mm?
W30x99 is 754.4 mm deep with a 266.7 mm wide flange; the web is 13.2 mm and the flange 17 mm thick. In metric section properties: Ix = 166,076 cm⁴, Sx = 4,408 cm³.
How much does a W30x99 weigh in kg?
147.3 kg per meter. A 6 m bar weighs 884 kg and a 12 m bar 1,768 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W30x99?
About the strong axis, Ix = 3,990 in⁴ (166,076 cm⁴) with section modulus Sx = 269 in³. About the weak axis, Iy = 128 in⁴ and Sy = 24.5 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W30x99 or W30x108 — what does one size up change?
W30x108 is about 9% heavier (108 vs 99 lb/ft) but about 12% stiffer (Ix 4,470 vs 3,990 in⁴). Going one step up within the same depth group is usually the cheapest way to cut deflection.
Values are entered from the governing standard’s published tables and cross-checked programmatically against its mass and section formulas before publication. Spotted an error? Write to advertising@metalabout.net — verified corrections ship within days. About