W14x398 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W14x398 is an American wide-flange beam 18.3 inches (464.8 mm) deep with a 16.6 in (421.6 mm) flange, weighing 398 pounds per foot (592.3 kg/m) — that is what the "398" 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 | 18.3 in (464.8 mm) |
| Flange width bf | 16.6 in (421.6 mm) |
| Web thickness tw | 1.77 in (45 mm) |
| Flange thickness tf | 2.85 in (72.4 mm) |
Weight & Cross-Section
| Weight per foot | 398 lb/ft (592.3 kg/m) |
| 20 ft bar | 7,960 lb |
| 40 ft bar | 15,920 lb |
| Area A | 117 in² (754.8 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 6,000 in⁴ (249,738 cm⁴) |
| Section modulus Sx | 656 in³ (10,750 cm³) |
| Radius of gyration rx | 7.16 in |
| Moment of inertia Iy | 2,170 in⁴ (90,322 cm⁴) |
| Section modulus Sy | 262 in³ (4,293 cm³) |
| Radius of gyration ry | 4.31 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W14x370 | 17.9 × 16.5 | 370 | 5,440 | 607 | −7 % | −9 % |
| W14x398 (this page) | 18.3 × 16.6 | 398 | 6,000 | 656 | — | — |
| W14x426 | 18.7 × 16.7 | 426 | 6,600 | 706 | +7 % | +10 % |
Deflection example
A simply supported W14x398 spanning 29 ft with a 10 kip point load at midspan deflects 0.05 in (E = 29,000 ksi, Ix = 6,000 in⁴). The L/360 serviceability limit for this span is 0.97 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W14x398 beam weigh?
W14x398 weighs 398 pounds per foot (592.3 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 7,960 lb and a 40 ft bar 15,920 lb.
What are the dimensions of a W14x398?
W14x398 is 18.3 in (464.8 mm) deep with a 16.6 in (421.6 mm) wide flange. The web is 1.77 in thick and the flanges are 2.85 in thick. Note the actual depth differs from the nominal W14 label — always design with the actual value.
What are the dimensions of a W14x398 in mm?
W14x398 is 464.8 mm deep with a 421.6 mm wide flange; the web is 45 mm and the flange 72.4 mm thick. In metric section properties: Ix = 249,738 cm⁴, Sx = 10,750 cm³.
How much does a W14x398 weigh in kg?
592.3 kg per meter. A 6 m bar weighs 3,554 kg and a 12 m bar 7,108 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W14x398?
About the strong axis, Ix = 6,000 in⁴ (249,738 cm⁴) with section modulus Sx = 656 in³. About the weak axis, Iy = 2,170 in⁴ and Sy = 262 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W14x398 or W14x426 — what does one size up change?
W14x426 is about 7% heavier (426 vs 398 lb/ft) but about 10% stiffer (Ix 6,600 vs 6,000 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