Steel Channel Sizes: C vs MC Chart
Standard American steel channels come in two AISC families: C shapes (American Standard Channels, 32 sections from C3x3.5 to C15x50) and MC shapes (Miscellaneous Channels, 40 sections from MC3x7.1 to MC18x58). Both are read the same way — depth in inches, then weight in pounds per foot — so a C8x11.5 is 8 inches deep and weighs 11.5 lb/ft. The practical difference for an estimator: C shapes are stocked everywhere and cheap per pound; MC shapes give you depths and flange widths the C series doesn't offer, but fewer service centers stock them and the price per hundredweight runs higher.
Full charts for both families below, then the questions that actually come up when you're pricing them.
What Are the Standard C Channel Sizes and Weights?
All 32 American Standard Channel sections, grouped by depth. The stick weight column is there because that's the number you actually order against — a 20-ft stick of C8x11.5 is 230 lb, and you'll catch a takeoff error faster comparing stick weights than lb/ft values.
| Designation | Depth (in) | Weight (lb/ft) | Weight per 20-ft stick (lb) |
|---|---|---|---|
| C3x3.5 | 3 | 3.5 | 70 |
| C3x4.1 | 3 | 4.1 | 82 |
| C3x5 | 3 | 5.0 | 100 |
| C3x6 | 3 | 6.0 | 120 |
| C4x4.5 | 4 | 4.5 | 90 |
| C4x5.4 | 4 | 5.4 | 108 |
| C4x6.25 | 4 | 6.25 | 125 |
| C4x7.25 | 4 | 7.25 | 145 |
| C5x6.7 | 5 | 6.7 | 134 |
| C5x9 | 5 | 9.0 | 180 |
| C6x8.2 | 6 | 8.2 | 164 |
| C6x10.5 | 6 | 10.5 | 210 |
| C6x13 | 6 | 13.0 | 260 |
| C7x9.8 | 7 | 9.8 | 196 |
| C7x12.25 | 7 | 12.25 | 245 |
| C7x14.75 | 7 | 14.75 | 295 |
| C8x11.5 | 8 | 11.5 | 230 |
| C8x13.75 | 8 | 13.75 | 275 |
| C8x18.75 | 8 | 18.75 | 375 |
| C9x13.4 | 9 | 13.4 | 268 |
| C9x15 | 9 | 15.0 | 300 |
| C9x20 | 9 | 20.0 | 400 |
| C10x15.3 | 10 | 15.3 | 306 |
| C10x20 | 10 | 20.0 | 400 |
| C10x25 | 10 | 25.0 | 500 |
| C10x30 | 10 | 30.0 | 600 |
| C12x20.7 | 12 | 20.7 | 414 |
| C12x25 | 12 | 25.0 | 500 |
| C12x30 | 12 | 30.0 | 600 |
| C15x33.9 | 15 | 33.9 | 678 |
| C15x40 | 15 | 40.0 | 800 |
| C15x50 | 15 | 50.0 | 1,000 |
Note the gaps: the C series jumps from 12-inch to 15-inch depth with nothing between, and stops at 15 inches entirely. When a drawing calls for a 13-inch or 18-inch channel, you're in MC territory.
What Are the Standard MC Channel Sizes and Weights?
All 40 Miscellaneous Channel sections. The MC series fills in around the C series — extra depths (13 and 18 inches), heavier sections at the same depth, and a handful of very light sections.
| Designation | Depth (in) | Weight (lb/ft) | Weight per 20-ft stick (lb) |
|---|---|---|---|
| MC3x7.1 | 3 | 7.1 | 142 |
| MC4x13.8 | 4 | 13.8 | 276 |
| MC6x6.5 | 6 | 6.5 | 130 |
| MC6x7 | 6 | 7.0 | 140 |
| MC6x12 | 6 | 12.0 | 240 |
| MC6x15.1 | 6 | 15.1 | 302 |
| MC6x15.3 | 6 | 15.3 | 306 |
| MC6x16.3 | 6 | 16.3 | 326 |
| MC6x18 | 6 | 18.0 | 360 |
| MC7x19.1 | 7 | 19.1 | 382 |
| MC7x22.7 | 7 | 22.7 | 454 |
| MC8x8.5 | 8 | 8.5 | 170 |
| MC8x18.7 | 8 | 18.7 | 374 |
| MC8x20 | 8 | 20.0 | 400 |
| MC8x21.4 | 8 | 21.4 | 428 |
| MC8x22.8 | 8 | 22.8 | 456 |
| MC9x23.9 | 9 | 23.9 | 478 |
| MC9x25.4 | 9 | 25.4 | 508 |
| MC10x6.5 | 10 | 6.5 | 130 |
| MC10x8.4 | 10 | 8.4 | 168 |
| MC10x22 | 10 | 22.0 | 440 |
| MC10x25 | 10 | 25.0 | 500 |
| MC10x28.5 | 10 | 28.5 | 570 |
| MC10x33.6 | 10 | 33.6 | 672 |
| MC10x41.1 | 10 | 41.1 | 822 |
| MC12x10.6 | 12 | 10.6 | 212 |
| MC12x14.3 | 12 | 14.3 | 286 |
| MC12x31 | 12 | 31.0 | 620 |
| MC12x35 | 12 | 35.0 | 700 |
| MC12x40 | 12 | 40.0 | 800 |
| MC12x45 | 12 | 45.0 | 900 |
| MC12x50 | 12 | 50.0 | 1,000 |
| MC13x31.8 | 13 | 31.8 | 636 |
| MC13x35 | 13 | 35.0 | 700 |
| MC13x40 | 13 | 40.0 | 800 |
| MC13x50 | 13 | 50.0 | 1,000 |
| MC18x42.7 | 18 | 42.7 | 854 |
| MC18x45.8 | 18 | 45.8 | 916 |
| MC18x51.9 | 18 | 51.9 | 1,038 |
| MC18x58 | 18 | 58.0 | 1,160 |
Watch the light ones. MC10x6.5 and MC10x8.4 — the old "junior channels" — are 10 inches deep but lighter than a C5x9. If your gut says "10-inch channel, call it 15 lb/ft" you'll be more than double on weight. Same trap in reverse with MC3x7.1: a 3-inch channel at more than twice the weight of a C3x3.5.
What Is the Difference Between C and MC Channels?
Both are hot-rolled channels with the same general cross-section. The differences that matter:
| C (American Standard) | MC (Miscellaneous) | |
|---|---|---|
| Sections in the series | 32 | 40 |
| Depth range | 3–15 in | 3–18 in |
| Dimension pattern | Standardized depth/flange proportions | Everything that doesn't fit the C pattern |
| Flange width at a given depth | Narrower | Generally wider (except the light "junior" sections) |
| Availability | Stocked at nearly every service center | Fewer mills roll them; often a mill order or a search |
| Typical cost per cwt | Baseline | Higher, sometimes substantially |
The design-side reason MC exists: at a given depth, an MC usually gives you a wider flange and more metal, which helps when you need bolt gauge on the flange or stiffness the C series can't provide. The estimating-side consequence: an MC callout is never a free substitution for a C of the same depth, in either direction. If the drawing says MC12x31 and your supplier quotes C12x30 "close enough," that's a different flange width and a different section — flag it, don't absorb it.
One more identification tip for old drawings: sections labeled "JR" or "junior channel" on legacy prints map to today's light MC sections (MC10x6.5, MC10x8.4, MC12x10.6, MC12x14.3).
How Do You Read a Channel Designation Like C8x11.5?
Same convention as W shapes: family, depth in inches, weight in pounds per foot.
- C8x11.5 — American Standard Channel, 8 in deep, 11.5 lb/ft
- MC13x50 — Miscellaneous Channel, 13 in deep, 50 lb/ft
Unlike some W shapes where nominal depth drifts from actual depth, channel depths are true — a C8 measures 8.00 inches, an MC13 measures 13.00 inches. That makes the weight math clean: a 32'-6" MC13x50 is 32.5 × 50 = 1,625 lb. No lookup needed for tonnage once you trust the designation.
The naming convention across all the AISC families — W, S, HSS, angles, channels — is covered in our AISC shape database guide if you're onboarding someone who's still translating callouts. For W shapes and angles specifically, the shapes reference has searchable dimension tables.
Where Do Channels Show Up on Drawings?
Channels are disproportionately a miscellaneous metals shape, which is exactly where takeoffs go wrong — the pieces are scattered across detail sheets instead of sitting in a tidy framing plan.
- Stair stringers — the classic. C12x20.7 and MC12x10.6 are the two most common stringer sections; MC12x10.6 shows up on lighter commercial stairs because it gives 12 inches of depth for tread connections at a third of the weight.
- Girts and eave struts — C8 and C10 sections on pre-engineered and conventional metal buildings.
- Equipment frames and skids — C6, C8, MC channels toed together into rectangular frames.
- Ladder rails, platform edges, grating supports — C3 through C6, usually in short pieces and high piece counts.
- Door and louver frames, embedded channels — often shown only in architectural details, easy to miss entirely.
Because so much channel lives in stairs, rails, and frames, it prices like misc metals: the labor per pound dwarfs the material. A hundred short C4 pieces with copes and holes is a very different job than the same tonnage in beam-line W shapes. Our miscellaneous metals estimating guide covers how to price that labor side.
Are MC Channels More Expensive Than C Channels?
Per pound, usually yes — and the spread is availability-driven, not steel-driven. C shapes in common sizes sit in every service center rack. Many MC sections are rolled infrequently by a small number of mills, so you're paying either a scarcity premium from a stocking distributor or waiting on a rolling schedule.
Practical rules when an MC shows up on your takeoff:
- Price it separately. Don't extend MC tonnage at your blended C-channel $/cwt. Get a real quote on the specific section.
- Check availability before bid day, not after award. MC13 and MC18 sections especially — if the rolling is eight weeks out, that belongs in your schedule assumptions.
- Ask about substitution paths in writing. Sometimes the EOR will accept a C15 or a built-up section in place of a hard-to-get MC. Sometimes they won't. Either answer changes your number.
How Do You Take Off Channels Without Missing Pieces?
Two channel-specific habits separate clean takeoffs from busted ones:
Toe orientation. A channel is not symmetric — the flanges point somewhere, and details will show toes-in, toes-out, toes-up, or toes-down. Orientation doesn't change the weight, but it changes the fab: which side gets the clip, where the holes land, whether grating sits on the flange or the web. Note orientation on your takeoff for framed channel assemblies, because a shop drawing built with the toes flipped is a rework ticket, not a shrug.
Pairs and mirrors. Channels run in matched sets constantly — two stringers per stair flight, mirrored left/right frame members, double channels back-to-back around a column. Drawings often detail one and note "OPP. HAND" or "TYP." for the mate. Count the physical pieces. A four-flight stair with one detailed stringer is eight stringers of steel, and missing that on a C12x20.7 x 14 ft is 2,300+ lb of material plus the labor that goes with it.
Piece-count errors are the whole game with channels — the sections are light, so the money is in how many there are, not what each one weighs. This is one place automated detection earns its keep: SteelFlo boxes every channel callout on every sheet, including the ones buried in stair and rail details, so the count you review is the count of labels actually on the drawings — at 95–99% accuracy with your verification pass on top, drawing on a database of 4,500+ sections across 6 standards.
Look Up Channel Weights Fast
Need a channel weight without pulling the manual? The free steel weight calculator covers every C and MC section above — pick the shape, enter the length, get pounds and tonnage instantly. No signup, and when you're ready to run a whole drawing set instead of one piece at a time, the first 3 takeoffs are free.