W12x279 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W12x279 is an American wide-flange beam 15.9 inches (403.9 mm) deep with a 13.1 in (332.7 mm) flange, weighing 279 pounds per foot (415.2 kg/m) — that is what the "279" 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 | 15.9 in (403.9 mm) |
| Flange width bf | 13.1 in (332.7 mm) |
| Web thickness tw | 1.53 in (38.9 mm) |
| Flange thickness tf | 2.47 in (62.7 mm) |
Weight & Cross-Section
| Weight per foot | 279 lb/ft (415.2 kg/m) |
| 20 ft bar | 5,580 lb |
| 40 ft bar | 11,160 lb |
| Area A | 81.9 in² (528.4 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 3,110 in⁴ (129,448 cm⁴) |
| Section modulus Sx | 393 in³ (6,440 cm³) |
| Radius of gyration rx | 6.16 in |
| Moment of inertia Iy | 937 in⁴ (39,001 cm⁴) |
| Section modulus Sy | 143 in³ (2,343 cm³) |
| Radius of gyration ry | 3.38 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W12x252 | 15.4 × 13 | 252 | 2,720 | 353 | −10 % | −13 % |
| W12x279 (this page) | 15.9 × 13.1 | 279 | 3,110 | 393 | — | — |
| W12x305 | 16.3 × 13.2 | 305 | 3,550 | 435 | +9 % | +14 % |
Deflection example
A simply supported W12x279 spanning 25 ft with a 10 kip point load at midspan deflects 0.06 in (E = 29,000 ksi, Ix = 3,110 in⁴). The L/360 serviceability limit for this span is 0.83 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W12x279 beam weigh?
W12x279 weighs 279 pounds per foot (415.2 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 5,580 lb and a 40 ft bar 11,160 lb.
What are the dimensions of a W12x279?
W12x279 is 15.9 in (403.9 mm) deep with a 13.1 in (332.7 mm) wide flange. The web is 1.53 in thick and the flanges are 2.47 in thick. Note the actual depth differs from the nominal W12 label — always design with the actual value.
What are the dimensions of a W12x279 in mm?
W12x279 is 403.9 mm deep with a 332.7 mm wide flange; the web is 38.9 mm and the flange 62.7 mm thick. In metric section properties: Ix = 129,448 cm⁴, Sx = 6,440 cm³.
How much does a W12x279 weigh in kg?
415.2 kg per meter. A 6 m bar weighs 2,491 kg and a 12 m bar 4,982 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W12x279?
About the strong axis, Ix = 3,110 in⁴ (129,448 cm⁴) with section modulus Sx = 393 in³. About the weak axis, Iy = 937 in⁴ and Sy = 143 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W12x279 or W12x305 — what does one size up change?
W12x305 is about 9% heavier (305 vs 279 lb/ft) but about 14% stiffer (Ix 3,550 vs 3,110 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