W12x72 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W12x72 is an American wide-flange beam 12.3 inches (312.4 mm) deep with a 12 in (304.8 mm) flange, weighing 72 pounds per foot (107.2 kg/m) — that is what the "72" 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 | 12.3 in (312.4 mm) |
| Flange width bf | 12 in (304.8 mm) |
| Web thickness tw | 0.43 in (10.9 mm) |
| Flange thickness tf | 0.67 in (17 mm) |
Weight & Cross-Section
| Weight per foot | 72 lb/ft (107.2 kg/m) |
| 20 ft bar | 1,440 lb |
| 40 ft bar | 2,880 lb |
| Area A | 21.1 in² (136.1 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 597 in⁴ (24,849 cm⁴) |
| Section modulus Sx | 97.4 in³ (1,596 cm³) |
| Radius of gyration rx | 5.31 in |
| Moment of inertia Iy | 195 in⁴ (8,116 cm⁴) |
| Section modulus Sy | 32.4 in³ (531 cm³) |
| Radius of gyration ry | 3.04 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W12x65 | 12.1 × 12 | 65 | 533 | 87.9 | −10 % | −11 % |
| W12x72 (this page) | 12.3 × 12 | 72 | 597 | 97.4 | — | — |
| W12x79 | 12.4 × 12.1 | 79 | 662 | 107 | +10 % | +11 % |
Deflection example
A simply supported W12x72 spanning 20 ft with a 10 kip point load at midspan deflects 0.17 in (E = 29,000 ksi, Ix = 597 in⁴). The L/360 serviceability limit for this span is 0.67 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W12x72 beam weigh?
W12x72 weighs 72 pounds per foot (107.2 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 1,440 lb and a 40 ft bar 2,880 lb.
What are the dimensions of a W12x72?
W12x72 is 12.3 in (312.4 mm) deep with a 12 in (304.8 mm) wide flange. The web is 0.43 in thick and the flanges are 0.67 in thick. Note the actual depth differs from the nominal W12 label — always design with the actual value.
What are the dimensions of a W12x72 in mm?
W12x72 is 312.4 mm deep with a 304.8 mm wide flange; the web is 10.9 mm and the flange 17 mm thick. In metric section properties: Ix = 24,849 cm⁴, Sx = 1,596 cm³.
How much does a W12x72 weigh in kg?
107.2 kg per meter. A 6 m bar weighs 643 kg and a 12 m bar 1,286 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W12x72?
About the strong axis, Ix = 597 in⁴ (24,849 cm⁴) with section modulus Sx = 97.4 in³. About the weak axis, Iy = 195 in⁴ and Sy = 32.4 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W12x72 or W12x79 — what does one size up change?
W12x79 is about 10% heavier (79 vs 72 lb/ft) but about 11% stiffer (Ix 662 vs 597 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