41 mm metric strut channel and the 1-5/8 in. series it maps to

41 mm and 1-5/8 in. are two names the catalog gives the same section: 41 is 41.3 rounded. That settles the profile. It does not settle the hole pattern or the length, and those are the two things a metric drawing usually gets wrong.

This page maps every metric callout onto the series number it is cut from, keeps the catalog’s rounded millimeters in one column and the one-decimal figures in another, and marks what is genuinely unconfirmed rather than smoothing it over.

Jump to: the one-table summary · 41x41 · 41x21 and 41x22 · 41x35 · 41x83 and deeper · hole pattern · 3 m or 3.05 m · M6–M12 nuts

Section reference

Where the 41 comes from

The catalog prints both names itself, in one sentence on p. 21: “Many Unistrut 1-5/8 in. (41mm) channel sections are available as curved pieces in both single and combination styles.” The next paragraph on the same page gives the rule: “Imperial dimensions are illustrated in inches. Metric dimensions are shown in millimeters and rounded to one decimal place.” So the series pages print 41.3, and the p. 24 selection chart rounds the same width to 41. Worked through, as computed here rather than printed anywhere: 1-5/8 in. × 25.4 = 41.275 mm; to one decimal place that is 41.3, and to a whole millimeter it is 41. The 41 mm series is not a separate product line that happens to sit beside the imperial one.

Source: Unistrut® General Engineering Catalog no. 17, p. 21 and 24 · Verified 2026-09-28

Section, steel thickness and hole patterns in one table

Everything a metric inquiry needs to name the section, one row per series: all eighteen, the nine single channels and the nine back-to-back pairs. Lengths and nut threads have their own tables further down: lengths, and the catalog nuts for each series and the metric nuts we supply.

Section mm is the one-decimal figure each series page prints; the whole-millimeter callouts are in the cross-map below. Steel is the catalog specification for the reference series — inches from each series page, millimeters from p. 21 — and never the thickness we supply, which is confirmed at quotation. Hole patterns are the codes the p. 24 selection chart marks for each single series, in the order it prints them; the chart lists no back-to-back pairs. Sizes and spacing for each code are in the suffix table. Source: Unistrut® General Engineering Catalog no. 17, p. 21, 24, and the series pages p. 25–56 · Verified 2026-09-28

Metric ↔ imperial cross-map

Metric callout to imperial series, both directions

Both tables are the same eighteen series — nine singles and nine back-to-back pairs — read the other way round, because a drawing may give either unit and a search may use either. A metric callout is the one-decimal section rounded to a whole millimeter: where the p. 24 chart prints the rounded value, the two agree for every series; for the back-to-back pairs, which that chart does not list, the callout is computed and marked so. Thickness figures are the catalog specification for the reference series; the thickness we supply is quoted on its own line and never merged into this column. Source: Unistrut® General Engineering Catalog no. 17, p. 21, 24, and p. 25–56 · Verified 2026-09-28

41x41, 41 x 41, 41×41 mm square — P1000, P1100, P2000, P4001, and P4101

41x21 and 41x22 (41 x 21, 41 x 22 mm) — P4000, P4100, and P3300

These are a millimeter apart as callouts and different sections in the hand: 41x22 is the 7/8 in. depth (P3300); 41x21 is the 13/16 in. depth (P4000 and P4100).

41x35 (41 x 35 mm) — P3000

P3000 is on its own here because its depth is its own. It is a 1-3/8 in. section, not a 13/16 in. or 7/8 in. one, and a drawing that calls it 41x21 or 41x22 is calling for a different channel.

41x83, 41x62 and every other section deeper than 41 mm — P5000, P5500 and seven back-to-back pairs

Holes, suffixes and lengths

The hole pattern is a separate question

The catalog prints six hole-pattern codes for the 41 mm profile, all dimensioned in inches with millimeters in parentheses: HS and H3 round holes; T, SL, and DS slots; and KO knockouts (p. 24–25). Their sizes and spacing, and the series each one is offered on, are in the suffix table below.

The hole size we can punch is the HS hole size in that table — our supply, not a catalog figure, not read off the catalog. The pattern it is punched in is named on the inquiry and confirmed at quotation.

A metric hole pattern is a different pattern, and we have no source for one. Catalog no. 17 does not cover it, our supply record says nothing about metric punching, and so this page prints no metric hole dimension at all. If your drawing specifies the hole, say so in the inquiry and it is confirmed at quotation — not assumed from the fact that the profile matches.

Hole patterns: Unistrut® General Engineering Catalog no. 17, p. 24–25, and Channel — hole patterns. Our hole size is from our own supply record, which says nothing about metric tooling · Verified 2026-09-27

Suffix rules on a metric order

A channel callout carries a hole-pattern code and a finish code; a stainless pipe clamp carries a third, written after a space. They come from three different systems and do not mix.

3 m or 3.05 m — they are not the same stick

Channel nuts: imperial in the catalog, M6 to M12 from us

What the catalog fits to each series: imperial nuts only. The table below gives, for each single channel, the part numbers and the thread range; it is the list to name if the nut can be imperial.

What we can supply: M6, M8, M10, and M12. The specific size and the channel series it has to suit are confirmed at quotation.

What we can publish: no metric part numbers. Catalog no. 17 prints none — the table below says so thread by thread.

What this page does not publish

What we do not publish, and what we can arrange instead

There is no load figure on this page. The catalog publishes its own under conditions it states itself: “All parts drawings illustrate only one application of each fitting”, and design load data “is based on the ultimate strength of the connection” with a stated safety factor, “unless otherwise noted” (p. 85). The fitting tables on p. 89 are tighter still — they hold only “when used in position shown”, with both ends of the beam supported, and with a P1010 nut and a 1/2 in. bolt.

A figure printed against a reference part in one drawn position is not the capacity of a frame, a trapeze or a rack, and what we quote is a candidate substitute made to order against the catalog number, so those figures are not ours to repeat. If your submittal needs numbers, give us the span and the connection detail and we price the evidence: measured coating thickness, mill certificate, and a third-party load test on the actual parts, arranged per order and confirmed at quotation. The catalog tables we do carry, with the safety factor printed beside each one, are on Channel span versus load and Nuts, labeled as the catalog’s throughout.

Conditions quoted from Unistrut® General Engineering Catalog no. 17, p. 85 and p. 89. The candidate-substitute position and the list of tests not yet run are our own · Verified 2026-09-19

Three things this page leaves unconfirmed

• The metric hole pattern. No source, no supply record. Asked and answered at quotation, not assumed.
• The letters C41. P1001 C41 itself is defined: p. 29 draws it as four 12 ga channels joined in a cross, 3-1/4 x 3-1/4 in. (82.6 x 82.6 mm), with its loading tables and section properties on p. 30–31, a row in the p. 24 strength table and an entry in the p. 22 pictorial index. What the catalog does not do is spell out what the letters stand for, and nothing in it describes the part as a metric P1001.
• Metric fastener hardware beyond the nut. Bolt grades, washers and their finishes are quoted, not published, because we hold no metric hardware table.

Quote

Where to go next

• Strut channel sizes and load chart — every series with gauge and allowable moment, plus the span table.
• Finishes — what we quote, the standard the catalog prints for each finish, and which series come in stainless.
• Pipe support parts — the assembly a metric cross member usually ends up in.
• Cross-reference table — if the drawing carries another brand’s number instead.

Frequently asked questions

Trademarks and who we are

Unistrut, B-Line, Superstrut, Power-Strut and Haydon, and the part numbers published under them, are trademarks or trade names of their respective owners. ChannelStrut is not affiliated with, authorized by, endorsed by or a distributor for any of them. Those brand names and part numbers are used here only to identify the products referred to.

ChannelStrut is run by Alex, a hardware sourcing specialist based in Fujian, China. We do not manufacture these parts — we source them from the mills that produce them. More on how the data is built: About.