# Flexible metal conduit sizes: FMC (reduced-wall 'greenfield') and liquid-tight LFMC, 3/8 to 4 in: ID and OD ranges, metric designators

> What are the ID and OD of 1/2 inch flexible metal conduit (FMC) and liquid-tight flexible metal conduit (LFMC)?

- Category: Tri-clamp & pipe › Pipe, tube & threads
- Kind: Standard part
- 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
- Page: https://xemstudio.com/objects/flexible-metal-conduit-fmc-lfmc-trade-sizes/ · JSON: https://xemstudio.com/api/geometry?object=flexible-metal-conduit-fmc-lfmc-trade-sizes · Plain text: https://xemstudio.com/objects/flexible-metal-conduit-fmc-lfmc-trade-sizes/sheet.txt
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**Exact dimensions.** True size, with no tolerance added.

## Notes

- 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.

## Sizes

| 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 |

## Where the files are

- 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)](https://flexiblewiringconduits.anacondasealtite.com/product/ul-flexible-metallic-conduit/-flexible-steel-conduit-flexible-metal-conduit-fmc) — web — Maker page; numbers only
- 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](https://www.mecampbell.com/media/pdf/CONFLEST.pdf) — web — Maker sheet; numbers only. The text read was garbled; the pairs were assigned smaller = ID, larger = OD
- Anamet Electrical (Anaconda Sealtite): [Type EF general construction liquid-tight flexible metal conduit: ID and OD min-max, 3/8 to 2 in](https://media.iewc.com/SpecificationSheets/39404.pdf) — web — Maker spec sheet; numbers only
- Anamet Electrical (Anaconda Sealtite): [Type MTC machine tool conduit (liquid-tight): ID and OD min-max, 3/8 to 2 in](https://media.iewc.com/SpecificationSheets/38314.pdf) — web — Maker spec sheet; numbers only
- Anamet Electrical (Anaconda Sealtite): [Item 37902, 3/8 in Type HFL liquid-tight conduit: ID and OD range](https://flexiblewiringconduits.anacondasealtite.com/printitem/specialty-conduits/liquid-tight-flexible-metal-conduit-lfmc-2/37902) — web — Maker page; numbers only

## Questions

**What is the OD of 1/2 inch flexible metal conduit?**

0.860–0.920 in (21.84–23.37 mm) for reduced-wall FMC (Type RWS / Type BR); liquid-tight Type EF is 0.820–0.840 in.

**What is the ID of 3/4 inch liquid-tight conduit?**

0.815–0.835 in (Type EF and Type MTC); OD 1.030–1.050 in (EF) or 1.009–1.034 in (MTC).

**What is the metric designator of 1 inch conduit?**

27 (Anamet's table: 1/2 is 16, 3/4 is 21, 1 is 27, 1-1/4 is 35, 1-1/2 is 41, 2 is 53).

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