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Where can I locate the EMC Number on my Mac? Are EMC Numbers unique? What are the limitations identifying a specific Mac using EMC Numbers?
EMC stands for "Electromagnetic Compatibility" and is further defined in electrical engineering as the "ability of electronic equipment to be a 'good electromagnetic neighbor': It neither causes, nor is susceptible to, electromagnetic interference (within the limits of applicable standards)."
For identification purposes, the advantages of EMC Numbers are that they are sometimes on the hardware itself and often are significantly more precise than Model Numbers. The disadvantages of EMC Numbers are that they are not available in the "About This Mac" section of Mac OS X, often are placed in inconvenient locations in small type, and are not externally present at all on some models. EMC Numbers on Macs commonly are not completely unique either.
However, because EMC Numbers can be more precise than Model Numbers, and are externally available on some models, they can be quite useful to track down a particular Mac or at least get "close enough" to an exact match to be worthwhile. If the Mac will not boot, in particular, EMC Numbers can be of great help.
The below image -- courtesy of KP's Surplus (a wholesaler that does an excellent job documenting exactly which Macs it has available for sale) -- provides an essentially perfect example of the strengths and weaknesses of using EMC Numbers for Mac identification.
Photo Credit: KP's Surplus
The two above Power Mac G5 models cannot be differentiated by Model Number, but they can be differentiated by EMC Number (both Model Number and EMC Number are located inconveniently on the bottom of the tower case). When combined with additional details on the inside of the computer (remove the access panel), it is possible to identify the exact Mac.
Photo Credit: Flickr User Boltron
The above iMac -- which has the Serial Number, EMC Number, and Model Number all inconveniently located on the bottom of the "foot" supporting the computer -- could most easily be identified by the W8745HB1X85 Serial Number with EveryMac.com's Ultimate Mac Lookup feature.
However, if the Serial Number had been removed or otherwise obscured (or not yet documented by EveryMac.com), the A1224 Model Number only would have been enough to narrow the field of potential matches to six (which could be narrowed to two based on processor speed and finally to one based on hard drive capacity). The 2133 EMC Number, on the other hand, only is applicable to two models, which already is close enough to be useful for many purposes -- such as determining the actual maximum RAM capacity -- and can be more quickly matched precisely by processor speed alone.
Photo Credit: EveryMac.com
The above MacBook -- from EveryMac.com's own collection -- cannot be identified by its external A1181 Model Number, as the Model Number is shared by 16 other MacBook models. By removing the battery, however, one can find the Serial Number, 2121 EMC Number, and a bit more about the MacBook as well (processor speed, original RAM, original hard drive, and original optical drive) in the lower left hand corner of the battery bay. In this case, one also could retrieve an exact match with the Serial Number, but the EMC Number, processor speed, and color also are enough to precisely identify the MacBook.
When looking for an EMC Number inside the battery bay of an applicable notebook Mac, be sure to check all the side walls of the compartment as well as the bottom as identifying information often is listed on a side wall. Also be sure to use the information on the computer, rather than on the battery, for identification of the computer.
Photo Credit: EveryMac.com (Courtesy of Reader Alius Panfilovas)
MacBook and MacBook Pro models with batteries that are not designed to be removed by the end user -- like the 13-Inch "Early 2011" MacBook Pro model above -- as well as pre-Late 2010 MacBook Air models have EMC Numbers internally listed and assigned in government compliance documents.
Unfortunately, however, EMC Numbers are not externally listed on these models themselves and consequently are not convenient for identification or differentiation. Nevertheless, EveryMac.com has documented the relevant EMC Numbers so they are available as an option for identification in situations where no other identifier is available readily.
To know where to look for the EMC Number on particular Macs, this also can help:
|Mac Series||EMC Number Location|
|Power Mac G3||Unavailable†|
|Power Mac G4||Back|
|Power Mac G5||Bottom|
|iMac||Bottom or Under "Foot"|
|Mac mini||Bottom or Inside**|
|PowerBook G4||Inside Battery Bay|
|MacBook||Inside Battery Bay, Inside, or Bottom*|
|MacBook Pro||Inside Battery Bay, Inside, or Bottom*|
|MacBook Air||Unavailable or Bottom††|
* Some MacBook and MacBook Pro models with batteries that are not designed to be removed by the end user have EMC Numbers internally listed and assigned in government compliance documents. Unfortunately, EMC Numbers are not externally listed on these models themselves and consequently are not convenient for identification or differentiation. Nevertheless, EveryMac.com has documented the relevant EMC Numbers.
** The aluminum "Unibody" Mac mini models have the EMC Number listed on the righthand side of the interior (with the ports facing you). It is visble upon removing the "spin off" bottom cover for internal access.
†† "Late 2010" MacBook Air models have the EMC Number listed on the bottom. Earlier MacBook Air models do not have the EMC Number externally listed, although they do have numbers internally listed nad assigned in government compliance documents.
A complete list of EMC Numbers from the By Identifier section of the site additionally may be useful. Please be particularly mindful of asterisks as this indicates an EMC Number is not listed externally on the hardware.
If EveryMac.com does not return a list of applicable Macs for a given EMC Number (or your Mac is not included), but you are able to track down your Mac using another identifier, please share any missing information. The Ultimate Mac Lookup feature is quite comprehensive, but it will become even more so with your additions. Thank you.