C12x30 — Dimensions, Weight & Section Properties
American Standard (C) channel per ASTM A6 / AISC Steel Construction Manual
C12x30 is an American Standard steel channel 12 inches (304.8 mm) deep with a 3.17 in (80.5 mm) flange, weighing 30 pounds per foot (44.6 kg/m) — that is what the "30" 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 | 12 in (304.8 mm) |
| Flange width bf | 3.17 in (80.5 mm) |
| Web thickness tw | 0.51 in (13 mm) |
| Avg. flange thickness tf | 0.501 in (12.7 mm) |
Weight & Cross-Section
| Weight per foot | 30 lb/ft (44.6 kg/m) |
| 20 ft bar | 600 lb |
| 40 ft bar | 1,200 lb |
| Area A | 8.81 in² (56.8 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 162 in⁴ (6,743 cm⁴) |
| Section modulus Sx | 27 in³ (442 cm³) |
| Radius of gyration rx | 4.29 in |
| Moment of inertia Iy | 5.12 in⁴ (213 cm⁴) |
| Section modulus Sy | 2.05 in³ (34 cm³) |
| Radius of gyration ry | 0.76 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| C12x25 | 12 × 3.05 | 25 | 144 | 24 | −17 % | −11 % |
| C12x30 (this page) | 12 × 3.17 | 30 | 162 | 27 | — | — |
Deflection example
A simply supported C12x30 spanning 19 ft with a 10 kip point load at midspan deflects 0.53 in (E = 29,000 ksi, Ix = 162 in⁴). The L/360 serviceability limit for this span is 0.63 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a C12x30 channel weigh?
C12x30 weighs 30 pounds per foot (44.6 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 600 lb and a 40 ft bar 1,200 lb.
What are the dimensions of a C12x30?
C12x30 is exactly 12 in (304.8 mm) deep with a 3.17 in (80.5 mm) wide flange. The web is 0.51 in thick; the tapered flanges average 0.5 in. Unlike W-shapes, C-channel depths are exact — a C10 is always 10.00 in deep.
What are the dimensions of a C12x30 in mm?
C12x30 is 304.8 mm deep with a 80.5 mm wide flange; the web is 13 mm and the flange 12.7 mm thick. In metric section properties: Ix = 6,743 cm⁴, Sx = 442 cm³.
How much does a C12x30 weigh in kg?
44.6 kg per meter. A 6 m bar weighs 268 kg and a 12 m bar 536 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a C12x30?
About the strong axis, Ix = 162 in⁴ (6,743 cm⁴) with section modulus Sx = 27 in³. About the weak axis, Iy = 5.12 in⁴ and Sy = 2.05 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
C12x30 or C12x25 — what does one size down change?
C12x25 is about 17% lighter (25 vs 30 lb/ft) but about 11% less stiff (Ix 144 vs 162 in⁴). Check deflection before downsizing — stiffness falls much faster than weight.
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