C15x33.9 — Dimensions, Weight & Section Properties
American Standard (C) channel per ASTM A6 / AISC Steel Construction Manual
C15x33.9 is an American Standard steel channel 15 inches (381 mm) deep with a 3.4 in (86.4 mm) flange, weighing 33.9 pounds per foot (50.4 kg/m) — that is what the "33.9" in the designation means. All values below are the standard AISC published section properties used in US structural design, with metric equivalents alongside. Channel flanges are tapered, so the flange thickness listed is the AISC average value.
Typical uses: stair stringers, trailer and equipment frames, rails, lintels, and bracing — anywhere a flat back against a wall or web is handy. 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 in (381 mm) |
| Flange width bf | 3.4 in (86.4 mm) |
| Web thickness tw | 0.4 in (10.2 mm) |
| Avg. flange thickness tf | 0.65 in (16.5 mm) |
Weight & Cross-Section
| Weight per foot | 33.9 lb/ft (50.4 kg/m) |
| 20 ft bar | 678 lb |
| 40 ft bar | 1,356 lb |
| Area A | 9.95 in² (64.2 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 315 in⁴ (13,111 cm⁴) |
| Section modulus Sx | 42 in³ (688 cm³) |
| Radius of gyration rx | 5.62 in |
| Moment of inertia Iy | 8.07 in⁴ (336 cm⁴) |
| Section modulus Sy | 3.09 in³ (51 cm³) |
| Radius of gyration ry | 0.9 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| C15x33.9 (this page) | 15 × 3.4 | 33.9 | 315 | 42 | — | — |
| C15x40 | 15 × 3.52 | 40 | 348 | 46.5 | +18 % | +10 % |
Deflection example
A simply supported C15x33.9 spanning 24 ft with a 10 kip point load at midspan deflects 0.55 in (E = 29,000 ksi, Ix = 315 in⁴). The L/360 serviceability limit for this span is 0.8 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a C15x33.9 channel weigh?
C15x33.9 weighs 33.9 pounds per foot (50.4 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 678 lb and a 40 ft bar 1,356 lb.
What are the dimensions of a C15x33.9?
C15x33.9 is exactly 15 in (381 mm) deep with a 3.4 in (86.4 mm) wide flange. The web is 0.4 in thick; the tapered flanges average 0.65 in. Unlike W-shapes, C-channel depths are exact — a C10 is always 10.00 in deep.
What are the dimensions of a C15x33.9 in mm?
C15x33.9 is 381 mm deep with a 86.4 mm wide flange; the web is 10.2 mm and the flange 16.5 mm thick. In metric section properties: Ix = 13,111 cm⁴, Sx = 688 cm³.
How much does a C15x33.9 weigh in kg?
50.4 kg per meter. A 6 m bar weighs 303 kg and a 12 m bar 605 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a C15x33.9?
About the strong axis, Ix = 315 in⁴ (13,111 cm⁴) with section modulus Sx = 42 in³. About the weak axis, Iy = 8.07 in⁴ and Sy = 3.09 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
C15x33.9 or C15x40 — what does one size up change?
C15x40 is about 18% heavier (40 vs 33.9 lb/ft) but about 10% stiffer (Ix 348 vs 315 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