What is the difference between C channels and MC channels?

C channels (American Standard Channels) and MC channels (Miscellaneous Channels) differ in flange geometry and production focus. C channels have a standard 16-2/3% (approximately 1:6) slope on the inner flange face, resulting in a tapered flange thickness. MC channels have wider flanges relative to their depth, with less flange slope (typically 5% or less), making them closer to parallel-flange channels. MC channels provide greater weak-axis bending strength and a flatter surface for connections compared to the same weight C channel. For example, an MC8x18 has flange width of 2.12" while a C8x18.8 has flange width of 1.89" despite similar weight and depth. MC channels are preferred for applications requiring bolted or welded connections to the flange face since the reduced slope provides a more uniform bearing surface. Both C and MC shapes are hot-rolled to ASTM A6 tolerances with ASTM A36 (Fy = 36 ksi) or A572 Gr 50 (Fy = 50 ksi) material.

How do you calculate steel channel weight per foot?

Steel channel weight per foot is directly proportional to the cross-sectional area: W (lb/ft) = A × 3.40, where A is the area in square inches and 3.40 = 490 lb/ft³ (steel density) / 144 in²/ft². Published values in the AISC Manual Table 1-5 for C channels and Table 1-6 for MC channels are authoritative. For example, C8x11.5 has nominal weight 11.5 lb/ft with area 3.38 in² (3.38 × 3.40 = 11.5 lb/ft). The weight designation in the shape name (e.g., C10x25) directly states the approximate weight of 25 lb/ft. For preliminary estimation without tables, approximate channel weight can be computed from plate analogy: web area = d × tw plus two flange areas = 2 × bf × tf, then multiply by 3.40. This approximation typically overestimates by 3-8% because it neglects the reduction at fillets. Note that actual delivered weight may vary within ASTM A6 rolling tolerances of ±2.5% from theoretical weight.

What are the most common applications for steel channels?

Steel channels serve numerous structural applications: stair stringers (C10x15 to C12x20, using two channels to support grating treads with bolt holes in the web), light beams (C8x11 to C12x25 for short spans under light loads where wide-flange shapes aren't economical), girts for wall framing (C6x8 to C8x13, metal building wall supports spanning horizontally between columns), purlins for roof framing (C8x11 to C10x15, spanning between roof beams to support metal deck or standing seam roof), bracing members (C6x10 to C8x18 as lateral bracing in braced frames and industrial structures), equipment supports (C10x15 to C12x25 for grating, platforms, and pipe rack cross-members), edge forms (C6x8 to C8x11 for concrete slab edge conditions), column bases (C6x8 to C10x20 for girts and base channel connections), and bridge stringers (C12x25 to C15x50 for short-span bridges and pedestrian bridges). Channels are efficient for combined bending and torsion applications where the open section allows easy connection access.

Why do channels have lower capacity in weak-axis bending compared to W-shapes of similar weight?

Channels have significantly lower weak-axis (y-y) bending capacity than W-shapes of similar weight due to their asymmetric geometry. A W-shape distributes material equally in two flanges about the web centerline, producing Iy from both flanges working together. A channel concentrates nearly all material on one side of the weak-axis bending plane, resulting in a much smaller Iy. For example, W8x18 (18 lb/ft) has Iy = 16.4 in⁴, while C8x18.8 (18.8 lb/ft) has Iy = 1.74 in⁴ — nearly a 10:1 ratio. This asymmetry also produces warping torsion when loaded through the shear center, which is located outside the section web. For this reason, channels used as beams should be laterally braced or paired back-to-back to create a doubly-symmetric built-up section (2C configuration), which approximately doubles Iy and eliminates warping torsion. AISC Section F6 provides separate provisions for weak-axis bending of channels. In compression, channels are governed by flexural-torsional buckling per AISC Section E4 due to the non-coincident centroid and shear center.

What ASTM specifications govern steel channel production?

The governing ASTM specifications for structural steel channels are: ASTM A36 (Fy = 36 ksi, Fu = 58 ksi) — the default specification for general structural channels, widely available and economical; ASTM A572 Grade 50 (Fy = 50 ksi, Fu = 65 ksi) — higher strength channels providing 39% greater load capacity for the same weight, used for heavily loaded members; ASTM A588 (Fy = 50 ksi) — weathering steel channels for exposed applications where no painting is desired; ASTM A992 (Fy = 50-65 ksi) — primarily for W-shapes but sometimes specified for channels by project requirements. Dimensional tolerances are per ASTM A6/A6M: depth ± 1/8" for d ≤ 12", ± 3/16" for d > 12"; flange width ± 1/8" for bf ≤ 4", ± 3/16" for bf > 4"; web thickness ± 0.015" maximum variation; weight ± 2.5% from theoretical mass. Mill test reports (MTRs) per ASTM A6 Section 11 provide heat analysis (chemistry) and mechanical properties (yield, tensile, elongation) for each heat.

Steel Channel Weight — C & MC Shape Weight Chart

Steel channels (C shapes and MC shapes) are used for beams, columns, bracing, stair stringers, and miscellaneous framing. C shapes (American Standard Channels) have a standard slope on the inner flange. MC shapes (Miscellaneous Channels) have wider flanges with less slope. This page provides weight data for common channel sections.

Standard Channels (C Shapes)

Designation	Weight (lb/ft)	Area (in²)	d (in)	bf (in)	tw (in)	Ix (in⁴)	Sx (in³)
C3x3.5	3.50	1.03	3.00	1.37	0.14	1.40	0.93
C3x4.1	4.10	1.20	3.00	1.41	0.17	1.64	1.09
C3x5	5.00	1.47	3.00	1.50	0.26	1.87	1.25
C3x6	6.00	1.76	3.00	1.60	0.36	2.07	1.38
C4x4.1	4.10	1.20	4.00	1.38	0.10	2.81	1.41
C4x5.4	5.40	1.58	4.00	1.43	0.16	3.40	1.70
C4x6.3	6.30	1.85	4.00	1.51	0.23	3.79	1.90
C4x7.3	7.30	2.14	4.00	1.58	0.30	4.10	2.05
C5x6.1	6.10	1.79	5.00	1.43	0.11	5.24	2.10
C5x6.7	6.70	1.97	5.00	1.49	0.16	5.72	2.29
C5x8.2	8.20	2.41	5.00	1.59	0.24	6.49	2.60
C5x9	9.00	2.64	5.00	1.64	0.29	6.85	2.74
C6x8.2	8.20	2.41	6.00	1.51	0.11	10.86	3.62
C6x10	10.00	2.94	6.00	1.61	0.19	12.59	4.20
C6x13	13.00	3.82	6.00	1.77	0.34	14.86	4.95
C7x9.8	9.80	2.88	7.00	1.57	0.10	17.33	4.95
C7x12.3	12.30	3.61	7.00	1.68	0.19	19.46	5.56
C7x14.8	14.80	4.35	7.00	1.78	0.28	21.15	6.04
C8x11.5	11.50	3.38	8.00	1.63	0.10	25.89	6.47
C8x13.8	13.80	4.05	8.00	1.73	0.17	28.88	7.22
C8x18.8	18.80	5.52	8.00	1.89	0.35	32.73	8.18
C9x13.4	13.40	3.94	9.00	1.71	0.11	37.79	8.40
C9x15	15.00	4.40	9.00	1.77	0.17	40.33	8.96
C9x20	20.00	5.87	9.00	1.93	0.35	45.05	10.01
C10x15.3	15.30	4.49	10.00	1.77	0.12	52.58	10.52
C10x20	20.00	5.87	10.00	1.89	0.24	60.62	12.12
C10x25	25.00	7.34	10.00	2.03	0.38	67.21	13.44
C10x30	30.00	8.81	10.00	2.16	0.51	72.32	14.46
C12x20.7	20.70	6.08	12.00	1.85	0.12	97.15	16.19
C12x25	25.00	7.34	12.00	1.96	0.24	109.63	18.27
C12x30	30.00	8.81	12.00	2.09	0.38	119.44	19.91
C15x33.9	33.90	9.95	15.00	2.13	0.22	214.04	28.54
C15x40	40.00	11.76	15.00	2.26	0.35	228.02	30.40
C15x50	50.00	14.69	15.00	2.47	0.55	245.36	32.71

Miscellaneous Channels (MC Shapes)

Designation	Weight (lb/ft)	Area (in²)	d (in)	bf (in)	tw (in)	Ix (in⁴)
MC6x7	7.00	2.06	6.00	1.77	0.10	11.38
MC6x12	12.00	3.52	6.00	2.00	0.26	15.57
MC7x19.1	19.10	5.61	7.00	2.14	0.36	29.32
MC8x8.5	8.50	2.50	8.00	1.87	0.10	22.41
MC8x18	18.00	5.29	8.00	2.12	0.29	34.87
MC8x20	20.00	5.87	8.00	2.17	0.34	37.19
MC8x21.4	21.40	6.28	8.00	2.20	0.38	38.35
MC10x6.8	6.80	2.00	10.00	1.77	0.08	29.35
MC10x8.4	8.40	2.47	10.00	1.84	0.13	33.72
MC10x22	22.00	6.46	10.00	2.22	0.33	67.95
MC10x25	25.00	7.34	10.00	2.29	0.39	72.70
MC10x28.5	28.50	8.37	10.00	2.37	0.46	76.72
MC10x33.6	33.60	9.87	10.00	2.48	0.57	82.13
MC12x10.6	10.60	3.11	12.00	1.92	0.10	60.64
MC12x14.3	14.30	4.20	12.00	2.01	0.19	68.30
MC12x31	31.00	9.10	12.00	2.40	0.45	126.37
MC13x31.8	31.80	9.34	13.00	2.37	0.39	149.22
MC13x35	35.00	10.28	13.00	2.44	0.45	157.24
MC13x40	40.00	11.76	13.00	2.55	0.56	166.64
MC18x42.7	42.70	12.54	18.00	2.55	0.39	371.34
MC18x45.8	45.80	13.45	18.00	2.59	0.45	381.17
MC18x51.9	51.90	15.24	18.00	2.68	0.56	396.80
MC18x58	58.00	17.03	18.00	2.77	0.68	410.51

Typical Channel Applications

Application	Typical Size	Notes
Stair stringers	C10x15 to C12x20	Two channels with grating treads
Light beams	C8x11 to C12x25	Short spans, light loads
Column bases	C6x8 to C10x20	Girts and base channels
Girts (wall framing)	C6x8 to C8x13	Metal building wall supports
Purlins (roof framing)	C8x11 to C10x15	Metal building roof supports
Bracing	C6x10 to C8x18	Lateral bracing members
Equipment supports	C10x15 to C12x25	Grating, platforms
Edge forms	C6x8 to C8x11	Concrete edge conditions
Bridge stringers	C12x25 to C15x50	Short-span bridges

ASTM Specifications

Spec	Grade	Fy (ksi)
A36	—	36
A572	Gr 50	50
A992	50	50 (some producers)

Most standard channels are A36. MC shapes may be A572 Gr 50 for structural applications.

Frequently Asked Questions

What is the difference between C and MC channels? C shapes (American Standard) have a standard flange slope (approximately 16.7%). MC shapes (Miscellaneous) have wider, less sloped flanges, providing better lateral stability and more efficient section properties.

What is the most common structural channel? C8x11.5 and C10x15.3 are among the most commonly specified channels for miscellaneous structural applications. C12x20.7 and C12x25 are common for stair stringers.

Can channels be used as beams? Yes, but channels have low weak-axis strength and are prone to lateral-torsional buckling. They must be laterally supported or used in pairs (back-to-back) for beam applications.

How much does a 10-foot piece of C8x11.5 weigh? 11.5 lb/ft × 10 ft = 115 lb.

Steel Weight Calculator — Weight by dimensions
Steel Angle Weight — L shape weights
Steel Weight per Foot — All shapes chart
Beam Sizes — W-shape section properties
Section Properties — Full section database

Disclaimer

This is a calculation tool, not a substitute for professional engineering certification. All results must be independently verified by a licensed Professional Engineer (PE) or Structural Engineer (SE) before use in construction, fabrication, or permit documents. The user is responsible for the accuracy of all inputs and the verification of all outputs.