W21x147 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W21x147 is an American wide-flange beam 22.1 inches (561.3 mm) deep with a 12.5 in (317.5 mm) flange, weighing 147 pounds per foot (218.8 kg/m) — that is what the "147" 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 | 22.1 in (561.3 mm) |
| Flange width bf | 12.5 in (317.5 mm) |
| Web thickness tw | 0.72 in (18.3 mm) |
| Flange thickness tf | 1.15 in (29.2 mm) |
Weight & Cross-Section
| Weight per foot | 147 lb/ft (218.8 kg/m) |
| 20 ft bar | 2,940 lb |
| 40 ft bar | 5,880 lb |
| Area A | 43.2 in² (278.7 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 3,630 in⁴ (151,091 cm⁴) |
| Section modulus Sx | 329 in³ (5,391 cm³) |
| Radius of gyration rx | 9.17 in |
| Moment of inertia Iy | 376 in⁴ (15,650 cm⁴) |
| Section modulus Sy | 60.1 in³ (985 cm³) |
| Radius of gyration ry | 2.95 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W21x132 | 21.8 × 12.4 | 132 | 3,220 | 295 | −10 % | −11 % |
| W21x147 (this page) | 22.1 × 12.5 | 147 | 3,630 | 329 | — | — |
| W21x166 | 22.5 × 12.4 | 166 | 4,280 | 380 | +13 % | +18 % |
Deflection example
A simply supported W21x147 spanning 35 ft with a 10 kip point load at midspan deflects 0.15 in (E = 29,000 ksi, Ix = 3,630 in⁴). The L/360 serviceability limit for this span is 1.17 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W21x147 beam weigh?
W21x147 weighs 147 pounds per foot (218.8 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 2,940 lb and a 40 ft bar 5,880 lb.
What are the dimensions of a W21x147?
W21x147 is 22.1 in (561.3 mm) deep with a 12.5 in (317.5 mm) wide flange. The web is 0.72 in thick and the flanges are 1.15 in thick. Note the actual depth differs from the nominal W21 label — always design with the actual value.
What are the dimensions of a W21x147 in mm?
W21x147 is 561.3 mm deep with a 317.5 mm wide flange; the web is 18.3 mm and the flange 29.2 mm thick. In metric section properties: Ix = 151,091 cm⁴, Sx = 5,391 cm³.
How much does a W21x147 weigh in kg?
218.8 kg per meter. A 6 m bar weighs 1,313 kg and a 12 m bar 2,625 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W21x147?
About the strong axis, Ix = 3,630 in⁴ (151,091 cm⁴) with section modulus Sx = 329 in³. About the weak axis, Iy = 376 in⁴ and Sy = 60.1 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W21x147 or W21x166 — what does one size up change?
W21x166 is about 13% heavier (166 vs 147 lb/ft) but about 18% stiffer (Ix 4,280 vs 3,630 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