Apple Tweaks Serial Number Format With New MacBook Pro

Information Removed at Request of Apple Legal

113124 apple serial numbers

With the release of refreshed MacBook Pro models earlier this week, Apple has apparently tweaked the format it uses for serial numbers on its devices, moving from an 11-character serial number to a 12-character sequence. For the time being, the change appears to be limited to the 17" MacBook Pro models, and it is unclear why the 13" and 15" models have not seen the same switch.

Apple's 11-character serial number system has utilized an alphanumeric format of PPYWWSSSCCC, comprising two digits "PP" denoting a plant code where the product was produced, a single digit "Y" denoting the year of manufacturing, two digits "WW" signifying the week of the year in which the machine was produced, a three-digit unique identifier "SSS" to distinguish between machines that would otherwise have the same serial numbers, and a final three digits "CCC" specifying the model.

The new 12-digit serial number format makes a few minor tweaks to the format, which we have been able to decipher. The increase in length for the new format, which takes on the sequence PPPYWSSSCCCC, can be attributed to changes to the length of the "P", "W", and "C" portions of the code.

The addition of a third "P" digit to assist in identifying the manufacturing location is a fairly straightforward change, although it remains to be seen whether existing plant codes will simply have a character such as a "0" appended to them or if the system is being entirely reworked. The difference in the "W" component is more significant, however, including a shift to alphanumeric codes that will make it a bit more difficult to decipher a machine's manufacturing at a simple glance. The "W" change is also related to a difference in how the "Y" component is used.

Under the previous format, the "Y" component of the serial number was simply the last digit of the year of manufacture, meaning that a machine produced this year would carry a "0" in that position. The number in that position would obviously recycle every ten years, but it should be relatively clear from Apple's product release history whether a given machine was produced in 2000 or 2010.

While leaving the length the same at one character, Apple has modified the "Y" component to include a letter code instead of a number, and the new system will reflect in that code not only the year of manufacture, but also whether it was manufactured in the first or second half of the year. Apple has elected to use 20 different letters in this position, omitting vowels A, E, I, O, and U, as well as B. As with the previous system, letters in this position will recycle every ten years. For 2010, machines with a "C" in this position will have been manufactured in weeks 1-26, while machines with a "D" will have been manufactured in weeks 27-52 or 53. Next year will see the use of codes "F" and "G", and so on.

With the reduction of the "W" component of the serial number to a single alphanumeric digit, Apple has had to roll out a new system for identifying the week in which a given machine was produced. Previously, the two-digit code simply reflected the week of the year, beginning with "01" and moving on through "52" or "53".

The new format utilizes one of 27 alphanumeric characters to denote the week of manufacture, beginning with 1-9 and moving on to letters, omitting 0, vowels A, E, I, O, and U, as well as B, S, and Z. Because the 27 possible characters can not account for all of the weeks in the year, the "W" component must be paired with the "Y" component to determine whether the machine was manufactured in the first or second half of the year, with the "W" codes recycling every six months.

The three-character alphanumeric "S" code for unique product identification remains the same under the new system, while the alphanumeric "C" code for identifying model numbers has been expanded from three characters to four.

The ability to decipher Apple's serial number code to ascertain when a given machine was produced has been used by many customers wishing to learn more about the age of their machines, particularly when it comes to production issues. Understanding whether production date makes a difference in whether machines do or do not suffer from a given issue can help pinpoint when fixes might have been deployed and either alert or reassure customers attempting to determine whether their machines might be affected.

Popular Stories

apple wallet drivers license feature iPhone 15 pro

iPhone Driver's Licenses: These 17 U.S. States Offer Them or Will Later

Thursday June 19, 2025 11:28 am PDT by
In select U.S. states, residents can add their driver's license or state ID to the Wallet app on the iPhone and Apple Watch, providing a convenient and contactless way to display proof of identity or age at select airports and businesses, and in select apps. Unfortunately, this feature continues to roll out very slowly since it was announced in 2021, with only nine U.S. states and Puerto...
iPhone 16 Battery Life Feature

iOS 26's New Battery Life Mode Available Only on These iPhone Models

Saturday June 21, 2025 9:02 am PDT by
Last week, we reported that iOS 26 introduces an opt-in Adaptive Power Mode on the iPhone, alongside the existing Low Power Mode. Apple says that Adaptive Power Mode can make "small performance adjustments" when necessary to extend an iPhone's battery life, including slightly lowering the display brightness or allowing some activities to "take a little longer." The full description of...
ios 26 call holding

iOS 26 Beta is Hiding a New Ringtone — Here's What It Sounds Like

Thursday June 19, 2025 7:25 pm PDT by
Apple is hiding a new ringtone within iOS 26. The new ringtone is an alternative version of the existing Reflection ringtone, which has been the default ringtone since the iPhone X was released in 2017. It was discovered within the code for the first developer beta of iOS 26, but it remains hidden, so you will not find it in the list of ringtones available in the Settings app for now. It...
iPhone 17 Pro Blue Feature Tighter Crop

iPhone 17 Pro Launching in Three Months With These 12 New Features

Saturday June 14, 2025 5:45 pm PDT by
The iPhone 17 Pro and iPhone 17 Pro Max are three months away, and there are plenty of rumors about the devices. Below, we recap key changes rumored for the iPhone 17 Pro models as of June 2025:Aluminum frame: iPhone 17 Pro models are rumored to have an aluminum frame, whereas the iPhone 15 Pro and iPhone 16 Pro models have a titanium frame, and the iPhone X through iPhone 14 Pro have a...
apple watch ultra 2 new black

Apple Watch Ultra 3 Finally Coming After Two-Year Hiatus

Monday June 16, 2025 8:45 am PDT by
Apple will finally deliver the Apple Watch Ultra 3 sometime this year, according to analyst Jeff Pu of GF Securities Hong Kong (via @jukanlosreve). The analyst expects both the Apple Watch Series 11 and Apple Watch Ultra 3 to arrive this year (likely alongside the new iPhone 17 lineup, if previous launches are anything to go by), according to his latest product roadmap shared with...
iOS 18

Apple Releases iOS 18.6 Public Beta

Wednesday June 18, 2025 10:24 am PDT by
Apple today seeded the first betas of upcoming iOS 18.6 and iPadOS 18.6 updates to public beta testers, with the betas coming just a few days after Apple provided the betas to developers. Testers who have signed up for beta updates through Apple's beta site can download iOS 18.6 and iPadOS 18.6 from the Settings app on a compatible device by going to General > Software Update. When the...
General Spotify Feature

Spotify Preparing to Launch Long-Awaited Lossless Audio Tier on iPhone

Thursday June 19, 2025 1:46 pm PDT by
Spotify appears to be gearing up to launch its long-awaited lossless music tier. Chris Messina (via TechCrunch) and Spicetify (via The Verge) spotted new lossless references within the code for Spotify's desktop app and web player. With assistance from Aaron Perris, MacRumors has confirmed that the latest beta of the Spotify app for the iPhone also contains new lossless-related code....
Craig Federighi No

John Gruber Reacts to Apple Declining His Interview After His Criticism

Wednesday June 18, 2025 8:10 pm PDT by
Every year between 2015 and 2024, at least one Apple executive agreed to be interviewed by Daring Fireball's John Gruber for a special WWDC episode of his podcast, The Talk Show. Last year, for example, Apple's software engineering chief Craig Federighi, marketing chief Greg Joswiak, and top AI researcher John Giannandrea joined Gruber on stage at the California Theatre in San Jose to discuss...
airpods 4 blue

Apple Offering Free AirPods — Here's How to Get Them

Tuesday June 17, 2025 6:33 am PDT by
Apple is running a new promotion that offers free AirPods to qualifying customers. Now through September 30, college and university students in the U.S., Canada, Mexico, and Singapore can receive free AirPods 4 when they purchase an eligible new Mac or iPad from Apple. AirPods Pro 2 are also available at a discount. If you do not want AirPods, the promotion also offers various other...