W16x40 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W16x40 is an American wide-flange beam 16 inches (406.4 mm) deep with a 7 in (177.8 mm) flange, weighing 40 pounds per foot (59.5 kg/m) — that is what the "40" 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 | 16 in (406.4 mm) |
| Flange width bf | 7 in (177.8 mm) |
| Web thickness tw | 0.305 in (7.7 mm) |
| Flange thickness tf | 0.505 in (12.8 mm) |
Weight & Cross-Section
| Weight per foot | 40 lb/ft (59.5 kg/m) |
| 20 ft bar | 800 lb |
| 40 ft bar | 1,600 lb |
| Area A | 11.8 in² (76.1 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 518 in⁴ (21,561 cm⁴) |
| Section modulus Sx | 64.7 in³ (1,060 cm³) |
| Radius of gyration rx | 6.63 in |
| Moment of inertia Iy | 28.9 in⁴ (1,203 cm⁴) |
| Section modulus Sy | 8.25 in³ (135 cm³) |
| Radius of gyration ry | 1.57 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W16x36 | 15.9 × 6.99 | 36 | 448 | 56.5 | −10 % | −14 % |
| W16x40 (this page) | 16 × 7 | 40 | 518 | 64.7 | — | — |
| W16x45 | 16.1 × 7.04 | 45 | 586 | 72.7 | +13 % | +13 % |
Deflection example
A simply supported W16x40 spanning 26 ft with a 10 kip point load at midspan deflects 0.42 in (E = 29,000 ksi, Ix = 518 in⁴). The L/360 serviceability limit for this span is 0.87 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W16x40 beam weigh?
W16x40 weighs 40 pounds per foot (59.5 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 800 lb and a 40 ft bar 1,600 lb.
What are the dimensions of a W16x40?
W16x40 is 16 in (406.4 mm) deep with a 7 in (177.8 mm) wide flange. The web is 0.31 in thick and the flanges are 0.51 in thick. Note the actual depth differs from the nominal W16 label — always design with the actual value.
What are the dimensions of a W16x40 in mm?
W16x40 is 406.4 mm deep with a 177.8 mm wide flange; the web is 7.7 mm and the flange 12.8 mm thick. In metric section properties: Ix = 21,561 cm⁴, Sx = 1,060 cm³.
How much does a W16x40 weigh in kg?
59.5 kg per meter. A 6 m bar weighs 357 kg and a 12 m bar 714 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W16x40?
About the strong axis, Ix = 518 in⁴ (21,561 cm⁴) with section modulus Sx = 64.7 in³. About the weak axis, Iy = 28.9 in⁴ and Sy = 8.25 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W16x40 or W16x45 — what does one size up change?
W16x45 is about 13% heavier (45 vs 40 lb/ft) but about 13% stiffer (Ix 586 vs 518 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