Flexible metal conduit sizes: FMC (reduced-wall 'greenfield') and liquid-tight LFMC, 3/8 to 4 in: ID and OD ranges, metric designators — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/flexible-metal-conduit-fmc-lfmc-trade-sizes/ (sheet CC BY 4.0) Basis: Anamet Electrical (Anaconda Sealtite) spec sheets for Type EF and Type MTC liquid-tight conduit and Type RWS flex, and Electri-Flex's Type BR sheet; ranges as the makers print them; numbers only Catalog version: 2026-10-20 Sizes: see table below - Flexible metal conduit comes in electrical trade sizes (3/8, 1/2, 3/4, 1 ... 4 in) with metric designators 12, 16, 21, 27, 35, 41, 53, 63, 78, 91 (as printed by Anamet for 3/8 to 3-1/2 in). The ID and OD are printed as ranges (min–max), not nominal values, so nothing is averaged to a single value; 1/2 in FMC is ID 0.625–0.645 in and OD 0.860–0.920 in; 1/2 in LFMC (Type EF) is ID 0.620–0.640 in and OD 0.820–0.840 in. Ranges are in inches. - FMC (also called greenfield, flex, or 'reduced-wall' flex, RWS) is steel flexible conduit without a jacket (Electri-Flex calls its Type BR 'non-jacketed'). Anamet's Type RWS page (10 of its 28 items shown in the text read, 3/8 to 3-1/2 in) and Electri-Flex's Type BR sheet print the same ID and OD ranges at every size they share; the exceptions are written as the sources print them: at 2 in the upper OD limit is 2.450 (Anamet) or 2.454 (Electri-Flex); at 2-1/2, 3 and 3-1/2 in Anamet prints the ID as a single value (2.500, 3.000, 3.500 in, the metric half of the cell reads 0.000 mm in the text, which is a page error) while Electri-Flex prints 2.500–2.700, 3.000–3.200 and 3.500 (min only). Electri-Flex's text was garbled when read; the pairs were assigned as the smaller = ID, larger = OD, which is how the sizes order. - LFMC (liquid-tight, 'Sealtite'-type) is metal conduit with a PVC jacket. Type EF (general construction) and Type MTC (machine tool) are listed 3/8 to 2 in with ID and OD ranges; the 3/8 in Type HFL page prints the same range as Type EF (ID 0.485–0.505, OD 0.690–0.710 in). Larger LFMC sizes (2-1/2 to 4 in) were not in the sheets read. Bend radius is shown only for Electri-Flex's Type BR (its 'inside radius' column, inches as printed); Anamet's sheets print an 'electrical bend radius' per size that is not copied. - EMT, rigid and IMC steel conduit tables are on emt-conduit and rigid-imc-emt-conduit-sizes-to-4-in; PVC conduit is on pvc-rigid-conduit-sch-40-80-nema-tc-2; knockouts and locknuts on conduit-knockout-diameters-nema-bulletin-71. No files: flexible conduit has no fixed shape. family trade size, in metric designator ID, in (min–max) OD, in (min–max) bend radius, in (Electri-Flex 'inside radius') LFMC Type EF (liquid-tight, general construction) 3/8 12 .485-.505 .690-.710 — LFMC Type EF (liquid-tight, general construction) 1/2 16 .620-.640 .820-.840 — LFMC Type EF (liquid-tight, general construction) 3/4 21 .815-.835 1.030-1.050 — LFMC Type EF (liquid-tight, general construction) 1 27 1.030-1.055 1.290-1.315 — LFMC Type EF (liquid-tight, general construction) 1-1/4 35 1.370-1.395 1.635-1.660 — LFMC Type EF (liquid-tight, general construction) 1-1/2 41 1.575-1.600 1.865-1.900 — LFMC Type EF (liquid-tight, general construction) 2 53 2.020-2.045 2.340-2.375 — LFMC Type MTC (machine tool, liquid-tight) 3/8 12 .485-.505 .679-.704 — LFMC Type MTC (machine tool, liquid-tight) 1/2 16 .620-.640 .818-.843 — LFMC Type MTC (machine tool, liquid-tight) 3/4 21 .815-.835 1.009-1.034 — LFMC Type MTC (machine tool, liquid-tight) 1 27 1.030-1.055 1.228-1.258 — LFMC Type MTC (machine tool, liquid-tight) 1-1/4 35 1.370-1.395 1.565-1.595 — LFMC Type MTC (machine tool, liquid-tight) 1-1/2 41 1.570-1.595 1.830-1.860 — LFMC Type MTC (machine tool, liquid-tight) 2 53 2.010-2.035 2.270-2.300 — FMC Type RWS (reduced-wall steel flex), Anamet 3/8 12 .375-.393 .560-.610 — FMC Type RWS (reduced-wall steel flex), Anamet 1/2 16 .625-.645 .860-.920 — FMC Type RWS (reduced-wall steel flex), Anamet 3/4 21 .812-.835 1.045-1.105 — FMC Type RWS (reduced-wall steel flex), Anamet 1 27 1.000-1.040 1.300-1.380 — FMC Type RWS (reduced-wall steel flex), Anamet 1-1/4 35 1.250-1.300 1.550-1.630 — FMC Type RWS (reduced-wall steel flex), Anamet 1-1/2 41 1.500-1.575 1.850-1.950 — FMC Type RWS (reduced-wall steel flex), Anamet 2 53 2.000-2.080 2.350-2.450 — FMC Type RWS (reduced-wall steel flex), Anamet 2-1/2 63 2.500 2.860-3.060 — FMC Type RWS (reduced-wall steel flex), Anamet 3 78 3.000 3.360-3.560 — FMC Type RWS (reduced-wall steel flex), Anamet 3-1/2 91 3.500 3.860-4.060 — FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 3/8 — .375-.393 .560-.610 2.0 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 1/2 — .625-.645 .860-.920 3.0 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 3/4 — .812-.835 1.045-1.105 4.0 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 1 — 1.000-1.040 1.300-1.380 5.0 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 1-1/4 — 1.250-1.300 1.550-1.630 6.2 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 1-1/2 — 1.500-1.575 1.850-1.950 7.5 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 2 — 2.000-2.080 2.350-2.454 10.0 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 2-1/2 — 2.500-2.700 2.860-3.060 12.5 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 3 — 3.000-3.200 3.360-3.560 15.0 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 3-1/2 — 3.500 3.860-4.060 17.5 FMC Type BR 'Blue Ribbon' reduced-wall steel flex, Electri-Flex 4 — 4.000 4.360-4.560 20.0 Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Anamet Electrical (Anaconda Sealtite): Type RWS reduced-wall steel flexible metal conduit (FMC): ID and OD range, 3/8 to 3-1/2 in (10 of 28 items shown) — web — Maker page; numbers only — https://flexiblewiringconduits.anacondasealtite.com/product/ul-flexible-metallic-conduit/-flexible-steel-conduit-flexible-metal-conduit-fmc - Electri-Flex (hosted by M. E. Campbell): Type BR Blue Ribbon reduced-wall flexible steel conduit: ID, OD, bend radius, 3/8 to 4 in — web — Maker sheet; numbers only. The text read was garbled; the pairs were assigned smaller = ID, larger = OD — https://www.mecampbell.com/media/pdf/CONFLEST.pdf - Anamet Electrical (Anaconda Sealtite): Type EF general construction liquid-tight flexible metal conduit: ID and OD min-max, 3/8 to 2 in — web — Maker spec sheet; numbers only — https://media.iewc.com/SpecificationSheets/39404.pdf - Anamet Electrical (Anaconda Sealtite): Type MTC machine tool conduit (liquid-tight): ID and OD min-max, 3/8 to 2 in — web — Maker spec sheet; numbers only — https://media.iewc.com/SpecificationSheets/38314.pdf - Anamet Electrical (Anaconda Sealtite): Item 37902, 3/8 in Type HFL liquid-tight conduit: ID and OD range — web — Maker page; numbers only — https://flexiblewiringconduits.anacondasealtite.com/printitem/specialty-conduits/liquid-tight-flexible-metal-conduit-lfmc-2/37902 No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=flexible-metal-conduit-fmc-lfmc-trade-sizes