W6x20 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W6x20 is an American wide-flange beam 6.2 inches (157.5 mm) deep with a 6.02 in (152.9 mm) flange, weighing 20 pounds per foot (29.8 kg/m) — that is what the "20" 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 | 6.2 in (157.5 mm) |
| Flange width bf | 6.02 in (152.9 mm) |
| Web thickness tw | 0.26 in (6.6 mm) |
| Flange thickness tf | 0.365 in (9.3 mm) |
Weight & Cross-Section
| Weight per foot | 20 lb/ft (29.8 kg/m) |
| 20 ft bar | 400 lb |
| 40 ft bar | 800 lb |
| Area A | 5.87 in² (37.9 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 41.4 in⁴ (1,723 cm⁴) |
| Section modulus Sx | 13.4 in³ (220 cm³) |
| Radius of gyration rx | 2.66 in |
| Moment of inertia Iy | 13.3 in⁴ (554 cm⁴) |
| Section modulus Sy | 4.41 in³ (72 cm³) |
| Radius of gyration ry | 1.5 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W6x16 | 6.28 × 4.03 | 16 | 32.1 | 10.2 | −20 % | −22 % |
| W6x20 (this page) | 6.2 × 6.02 | 20 | 41.4 | 13.4 | — | — |
| W6x25 | 6.38 × 6.08 | 25 | 53.4 | 16.7 | +25 % | +29 % |
Deflection example
A simply supported W6x20 spanning 10 ft with a 10 kip point load at midspan deflects 0.3 in (E = 29,000 ksi, Ix = 41.4 in⁴). The L/360 serviceability limit for this span is 0.33 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W6x20 beam weigh?
W6x20 weighs 20 pounds per foot (29.8 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 400 lb and a 40 ft bar 800 lb.
What are the dimensions of a W6x20?
W6x20 is 6.2 in (157.5 mm) deep with a 6.02 in (152.9 mm) wide flange. The web is 0.26 in thick and the flanges are 0.37 in thick. Note the actual depth differs from the nominal W6 label — always design with the actual value.
What are the dimensions of a W6x20 in mm?
W6x20 is 157.5 mm deep with a 152.9 mm wide flange; the web is 6.6 mm and the flange 9.3 mm thick. In metric section properties: Ix = 1,723 cm⁴, Sx = 220 cm³.
How much does a W6x20 weigh in kg?
29.8 kg per meter. A 6 m bar weighs 179 kg and a 12 m bar 357 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W6x20?
About the strong axis, Ix = 41.4 in⁴ (1,723 cm⁴) with section modulus Sx = 13.4 in³. About the weak axis, Iy = 13.3 in⁴ and Sy = 4.41 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W6x20 or W6x25 — what does one size up change?
W6x25 is about 25% heavier (25 vs 20 lb/ft) but about 29% stiffer (Ix 53.4 vs 41.4 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