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 oct 2024 mac tease

Apple Expected to Announce These Two to Three Products 'This Week'

Sunday October 12, 2025 7:05 am PDT by
Apple plans to announce new products "this week," according to Bloomberg's Mark Gurman. Apple's "Mac Your Calendars" teaser last October In his Power On newsletter today, Gurman said the products set to be updated this week include the iPad Pro, Vision Pro, and "likely" the base 14-inch MacBook Pro, with all three likely to receive a spec bump with Apple's next-generation M5 chip. Gurman...
iOS 26 Feature

Apple Preparing iOS 26.0.2 Update for iPhones

Saturday October 11, 2025 6:59 pm PDT by
Apple's software engineers are internally testing iOS 26.0.2, according to MacRumors logs, which have been a reliable indicator of upcoming iOS versions. iOS 26.0.2 will likely be a minor update that addresses bugs and/or security vulnerabilities, but we do not know any specific details yet. The update will likely be released within the next few weeks. Last month, Apple released iOS...
Apple TV Plus Feature 2 Magenta and Blue

Apple TV+ Being Rebranded as Apple TV

Monday October 13, 2025 8:25 am PDT by
Buried in its announcement about "F1: The Movie" making its streaming debut on December 12, Apple has also announced that Apple TV+ is being rebranded as simply Apple TV. A single line near the end of the press release states "Apple TV+ is now simply Apple TV, with a vibrant new identity," though Apple's website has yet to be updated with any changes, so we're unsure on the details of the...
iPhone 17 Pro Colors

iPhone 18 Pro Already Rumored to Have These 6 New Features

Saturday October 11, 2025 10:10 am PDT by
While the iPhone 18 Pro and iPhone 18 Pro Max are still nearly a year away, a handful of new features and changes have already been rumored for the devices. Below, we have recapped some of the early iPhone 18 Pro rumors so far. Smaller Dynamic Island The standard iPhone 18, iPhone 18 Pro, and iPhone 18 Pro Max will be equipped with a slightly smaller Dynamic Island, but the devices will...
10

Apple to Launch New Products Starting Next Week, Claims Dubious Leak [Updated]

Friday October 10, 2025 5:57 am PDT by
Update: the Naver account appears to be referencing a speculative post on X by Vadim Yuryev, dated October 6. The original article follows. Apple will announce new products through a series of press releases beginning as soon as next week, according to a dubious claim posted on the Korean blog Naver. The Naver blog account yeux1122, which aggregates rather than originates Apple...
All AirPods 2025

Apple Reportedly Working on New AirPods Pro, AirPods 5, and H3 Chip

Sunday October 12, 2025 9:24 am PDT by
After releasing AirPods Pro 3 last month, Apple is already working on the next AirPods Pro, according to Bloomberg's Mark Gurman. It is unclear if the new AirPods Pro would be branded as AirPods Pro 4, or if they would be considered an updated version of AirPods Pro 3. Gurman did not take a position, opting to describe them as a "new version" of the "high-end in-ear buds." AirPods Pro 2...
Meta Ray Ban Glasses

Apple's Smart Glasses With In-Lens Display May Feature Two Modes

Sunday October 12, 2025 9:43 am PDT by
Apple's second-generation smart glasses with an in-lens display may have two modes, depending on which device they are connected to. Meta Ray-Bans without an in-lens display In his Power On newsletter today, Bloomberg's Mark Gurman said he was told a future version of Apple's smart glasses may be able to run a full version of the visionOS operating system when they are paired with a Mac, and...
clips app hands on thumb

Apple's Clips App Discontinued

Saturday October 11, 2025 9:06 am PDT by
Apple has essentially discontinued Clips, its video-editing app designed to allow users to combine video clips, images, and photos with voice-based titles, music, filters, and graphics to create enhanced videos that can be shared on social media sites. The app has been removed from the App Store, and a support document on Apple's site says that the app is no longer being updated and would no ...
apple vision pro orange

Vision Pro Future Uncertain as All Headset Development Is Seemingly Paused

Saturday October 11, 2025 1:00 am PDT by
Recent reports suggest that there are now no redesigned Apple Vision headsets in active development, with the company's focus pivoting decisively to smart glasses. When Apple announced the Vision Pro in mid-2023, it described the device as the dawn of "spatial computing," a new paradigm that would eventually rival the iPhone in importance. With a $3,499 starting price, intricate design and...