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IEC Motor Frame Decoder

Type an IEC frame (112M, 132S, 90L) and read its shaft height, shaft diameter, foot spacing, typical power, and the nearest NEMA frame. Reverse a NEMA frame (213T) back to IEC. Built from IEC 60072-1 and the Baldor/ABB, Nidec/US Motors, and ESR cross-reference charts, with the one rule every cross-reference chart buries: the metric and imperial frames are nearest, not a drop-in.

A code-to-property lookup decoder for IEC metric motor frames. Type any IEC frame designation (56 through 355, including the S/M/L length variants) and the decoder returns the shaft centre height in millimetres (the frame number itself, per IEC 60072-1), the shaft diameter with the smaller 2-pole value called out on frames 225 and larger, the foot mounting dimensions A and B, the typical power band by pole count, the parsed mounting code (B3 foot, B5 flange, B14 face, B35 foot-and-flange), and the nearest NEMA frame from the ESR IEC/NEMA comparison chart. It also runs in reverse: enter a NEMA frame (143T, 213T, 256T, 445T) and it returns the nearest IEC frame. Every cross-reference output carries the mandatory caveat that the nearest NEMA frame is not a drop-in: the shaft diameter, keyway, foot bolt pattern, and bolt-hole diameter all differ between metric and imperial frames, and the decoder quantifies the difference by comparing the two shaft heights in millimetres so you can see exactly how close (or not) the match is.

Pro Tip: Two things get missed on an IEC-to-NEMA swap and both cost a second trip. First, the length letter. IEC 132S and 132M share the same 132 mm shaft height but different foot spacing (B = 140 mm vs 178 mm), so a base drilled for 132S will not bolt up a 132M without slotting the feet. Read the exact letter off the nameplate, not just the number. Second, the 2-pole shaft. On frames 225 and up, the 2-pole (roughly 3000 RPM) build uses a smaller shaft than the 4-pole build (250 frame: 60 mm at 2-pole vs 65 mm at 4-pole). If you size a coupling bore or a taper bushing off the 4-pole dimension and the motor turns out to be 2-pole, the bushing will not grip. The decoder calls both numbers out so you order the right bore the first time.

Read the IEC Motor Frame Guide for the full frame series, the S/M/L length-letter logic, the B3/B5/B14 mounting codes, and why the NEMA cross-reference is approximate

IEC Motor Frame Guide →

Decode the NEMA side: shaft diameter, expected FLA, NEC 430 wire sizing, and the rest of the nameplate

Motor Nameplate Decoder →

Decode a NEMA enclosure Type (4X, 12, 7) that the motor or its junction box may carry

NEMA Enclosure Rating Decoder →

Decode an IP rating on an imported IEC-frame motor nameplate

IP Rating Decoder (IEC 60529) →

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IEC Motor Frame Decoder
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How It Works

  1. Type the IEC frame

    Enter any IEC frame designation. The decoder accepts "112M", "IEC 132S", "90L", "160M B35", and "132" on its own (a bare shaft height). The normalizer strips the "IEC" and "IM" prefixes, drops spaces and dashes, and uppercases the result. A bare height like "132" resolves to the most common length variant (132M) and lists the others (132S) so you can pick the one on the nameplate.

  2. Read the frame properties

    The matched banner shows the frame, its shaft centre height in millimetres (the frame number by definition), and the shaft diameter (with the smaller 2-pole value if the frame is 225 or larger). The Properties card adds the length letter and its meaning, the foot spacing A by B, the parsed mounting code if you entered one, and a confidence label tied to how the value was sourced.

  3. Check the typical power band

    A small table shows the typical power in kW for 2-pole, 4-pole, and 6-pole builds of that frame. IEC, unlike NEMA, does not bind a horsepower to a frame, so these are typical ranges for a standard-efficiency motor. A premium-efficiency (IE3 or IE4) motor of the same rating may sit one frame larger. Confirm the actual power from the nameplate.

  4. Walk the NEMA cross-reference

    The cross-reference card names the nearest NEMA frame from the ESR comparison chart and shows the shaft height of both frames in millimetres, so the gap is explicit. A 1 to 4 mm gap is typical; a larger gap (the IEC 100L to NEMA 145T pairing is about 11 mm) shows the chart is matching on power and mounting overlap, not shaft height alone. The card states plainly that the shaft, keyway, and bolt pattern differ and a swap needs an adapter base or re-drilled feet.

  5. Reverse a NEMA frame

    Enter a NEMA frame (143T, 213T, 256T, 445T) instead and the decoder runs the cross-reference in reverse, returning the nearest IEC frame. NEMA frames not in the chart (and the fractional 42/48/56 frames, which collide with small IEC frame numbers) return a clear no-match rather than a wrong guess.

  6. Export the decode

    PDF export produces a branded report with the frame properties, the typical-power table, the IEC-to-NEMA shaft-height comparison table, the field notes, and the source citation. CSV export packages the same fields for spreadsheet import or order paperwork. The share button puts the exact frame in a coworker browser without retyping.

Built For

  • A maintenance planner holding a failed imported pump motor stamped "132S B35" and needing the shaft height, foot pattern, and the nearest NEMA frame to source a replacement
  • A reliability engineer cross-referencing a metric gearmotor (160L) to a NEMA 256T frame and confirming the swap needs an adapter base, not a bolt-in
  • A buyer reading "112M" off a European nameplate and confirming the typical 4 kW rating and the 184T NEMA equivalent before requesting a quote
  • A millwright sizing a coupling bore for a 250 frame motor and catching that the 2-pole build uses a 60 mm shaft, not the 65 mm 4-pole shaft
  • A panel shop confirming whether a "132" motor on a drawing is 132S or 132M before ordering the slide base, because the foot spacing differs
  • A field tech decoding a B5 flange-mount designation on an IEC motor and confirming it is the large clearance flange (FF), not the small B14 face flange
  • An estimator translating a NEMA 213T spec on a US drawing back to the IEC 132S frame for an overseas-sourced motor
  • A trainer walking an apprentice through why an IEC frame number is the shaft height in millimetres while a NEMA frame number is a coded value

Features & Capabilities

Cited Dimension Data

Every IEC dimension is sourced from the Baldor/ABB and Nidec/US Motors IEC frame charts, which agree cell for cell, and confirmed against the WEG critical-dimensions poster. The shaft height is the frame number by definition (IEC 60072-1:2022). The NEMA cross-reference and the typical power bands come from the ESR IEC/NEMA comparison chart. Each frame carries a confidence label, and the gated IEC 60072-1 standard is cited as the authority even where its paid tables were not read line by line.

Nearest, Not A Drop-In, Quantified

The cross-reference does not just name a NEMA frame; it shows the shaft height of both frames in millimetres and the gap between them, so you see how approximate the match is. The card, a dedicated field note, the warnings, and the export all repeat that the shaft diameter, keyway, foot bolt pattern, and bolt-hole diameter differ and that a physical swap needs an adapter base or re-drilled feet.

2-Pole Shaft Diameter Callout

On frames 225 and larger, a 2-pole (roughly 3000 RPM) motor uses a smaller shaft than the 4-pole and slower builds. The decoder stores both diameters and adds a field note whenever the frame has a 2-pole reduction, so a coupling or bushing bore is sized off the right number.

Bidirectional IEC and NEMA Lookup

The decoder runs both directions. IEC to NEMA returns the nearest NEMA frame; NEMA to IEC returns the nearest IEC frame by inverting the same chart. Fractional NEMA frames (42, 48, 56) that collide with small IEC frame numbers, and NEMA frames not in the chart, return a clear no-match instead of a wrong guess.

Length-Letter And Mounting-Code Parsing

The S/M/L length letter is decoded into its meaning (it changes the foot spacing and rating band, not the shaft height), and the IEC 60034-7 mounting codes (B3 foot, B5 flange, B14 face, B34, B35 foot-and-flange) are parsed orthogonally from the frame so "160M B35" returns both the frame and the mounting.

PDF And CSV Export

PDF export uses the shared ToolGrit programmatic generator: frame properties, the typical-power table, the IEC-to-NEMA shaft-height comparison table, field notes, and the source citation, with a branded header and the standard disclaimer footer. CSV export packages the same fields for spreadsheet import or order paperwork.

Cross-Link To The Motor Nameplate Decoder

When the decoder finds a nearest NEMA frame, it deep-links into the Motor Nameplate Decoder with that NEMA frame pre-loaded, so you can pick up the NEMA-side shaft diameter, expected FLA, and NEC 430 wire sizing in one click. The two tools cover the metric and imperial halves of the same job.

Light And Dark Mode, WCAG AA

Standard ToolGrit light and dark theme with WCAG AA contrast on the confidence labels and the shaft-height-gap callout. The matched banner uses an aria-live region so screen readers announce the decode when the frame changes. The mobile layout at 375 px keeps the power table readable inside a horizontal-scroll container.

Comparison

IEC frame Shaft height (mm) Shaft dia D (mm) Typical 4-pole (kW) Nearest NEMA frame
71 71 14 0.37 NEMA 42
80 80 19 0.75 NEMA 48
90S / 90L 90 24 1.1 / 1.5 NEMA 56
100L 100 28 2.2 to 3.0 145T
112M 112 28 4.0 184T
132S / 132M 132 38 5.5 / 7.5 213T / 215T
160M / 160L 160 42 11 / 15 254T / 256T
180M / 180L 180 48 18.5 / 22 284T / 286T
200L 200 55 30 to 37 326T
225S / 225M 225 60 (55 at 2-pole) 37 / 45 364T / 365T
250M 250 65 (60 at 2-pole) 55 405T
280S / 280M 280 75 (65 at 2-pole) 75 / 90 444T / 445T
315S / 315M 315 80 (65 at 2-pole) 110 / 132 no chart value

References

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Frequently Asked Questions

The number is the shaft centre height in millimetres: the distance from the bottom of the mounting feet to the centre of the shaft. An IEC 112 frame has a 112 mm shaft height. This is direct and unambiguous, set by IEC 60072-1. It is different from a NEMA frame number, which is a coded value (for a NEMA T-frame, the first two digits divided by 4 give the shaft height in inches; for a fractional frame like 56, the number divided by 16 gives inches).
They share the same 132 mm shaft height but a different body length, which changes the foot spacing (the B dimension). 132S has B = 140 mm; 132M has B = 178 mm. The S/M/L letter sets the length and the rating band, not the shaft height. A motor base drilled for 132S will not bolt up a 132M without slotting the feet, so you have to match the exact letter on the nameplate, not just the number.
Not directly. The nearest NEMA frame has a similar shaft height, but the shaft diameter, keyway, foot bolt pattern, and bolt-hole diameter all differ between the metric and imperial systems. A swap needs an adapter base or re-drilled feet and usually a different coupling or bushing for the shaft. The decoder calls this out on every cross-reference and shows the shaft-height gap so you can see how close the two frames actually are.
On frames 225 and larger, the 2-pole (roughly 3000 RPM) build uses a smaller shaft than the 4-pole and slower builds. For example, a 250 frame has a 65 mm shaft at 4-pole but 60 mm at 2-pole. If you size a coupling bore or a taper bushing off the wrong one, it will not fit. The decoder shows both and adds a note so you order the right bore.
It is a typical value, not a fixed rating. IEC does not bind a power to a frame the way NEMA does, so a frame is built across a band of ratings, and a premium-efficiency (IE3 or IE4) motor often sits one frame larger than a standard-efficiency motor of the same power. Use the typical kW to sanity-check, but confirm the actual power from the nameplate.
They are IEC 60034-7 mounting arrangements, parsed separately from the frame size. B3 is foot-mounted with a horizontal shaft, the default. B5 is flange-mounted with a large clearance flange (the FF type) and through-holes, no feet. B14 is face-mounted with a small flange (the C-DIN type) and tapped holes, no feet. B35 is foot-mounted with a B5 flange added, the common foot-and-flange combination. The decoder recognises these whether you write "160M B35" or "160M B-35".
Because the ESR cross-reference chart matches on a combination of power and mounting overlap, not on shaft height alone. IEC 100 is 100 mm; NEMA 145T is 3.5 inches, about 88.9 mm. The chart still pairs them because their power ratings and bolt patterns line up better than the next NEMA frame up. The decoder shows the gap so you know the pairing is a practical equivalence, not a dimensional match, which is exactly why it is nearest and not a drop-in.

Learn More

Shops & Outbuildings

IEC Motor Frame Guide: Frame Number Is Shaft Height, S/M/L Length, B3/B5/B14 Mounting, and the NEMA Cross-Reference

Plain-language IEC motor frame reference. The frame number is the shaft centre height in millimetres (IEC 60072-1); the S/M/L letter sets the body length and foot spacing, not the shaft height; the B3/B5/B14/B35 mounting codes; the 2-pole shaft-diameter reduction on frames 225 and larger; and why the IEC-to-NEMA cross-reference is nearest, not a drop-in. Companion to the IEC Motor Frame Decoder.

Read Guide →
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Hazardous Area Code Guide: NEC Class/Division vs IEC/IECEx Zone vs ATEX, and the Reversed Gas Groups

Plain-language hazardous-area marking reference. How the NEC Class/Division system, the IEC/IECEx Zone system, and the ATEX marking line up; why the gas groups run backwards (NEC Group A is IEC IIC); why a Division is not a single Zone; the temperature classes; and how to read an Ex string position by position. Companion to the Hazardous Area Code Translator.

Read Guide →
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Wire & Cable Type Guide: What the Letters Mean, the "-2" Wet Rating, and the 110.14(C) Termination Trap

Plain-language wire and cable marking reference. The T/H/HH/W/N/X letter system; why the "-2" suffix is a 90 C wet rating, not a version number; the NEC 110.14(C) rule that a 90 C conductor is still sized from the 60 or 75 C termination column; NM-B and UF-B taken from the 60 C column; the flexible-cord letters; and AC versus MC grounding. Companion to the Wire & Cable Type Decoder.

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