Last Updated: May 5th, 2014


This handy tool will calculate the build date for a given Android build number. Just input the build number and press Date It! The rules, as per Android developer docs are as follows:

Starting with Cupcake, individual builds are identified with a short build code, e.g. FRF85B.

The first letter is the code name of the release family, e.g. F is Froyo.

The second letter is a branch code that allows Google to identify the exact code branch that the build was made from, and R is by convention the primary release branch.

The next letter and two digits are a date code. The letter counts quarters, with A being Q1 2009. Therefore, F is Q2 2010. The two digits count days within the quarter, so F85 is June 24 2010.

Finally, the last letter identifies individual versions related to the same date code, sequentially starting with A; A is actually implicit and usually omitted for brevity.

The date code is not guaranteed to be the exact date at which a build was made, and it is common that minor variations added to an existing build re-use the same date code as that existing build.

Input the build number here:  
  • http://www.androidpolice.com/ Artem Russakovskii

    Thoughts, suggestions, bugs? Throw them in here.

    • http://google.com/+derekross Derek Ross

      Best. Tool. Ever. Whenever a new build leaks or becomes available it's always a pain in the ass to figure it out manually. Then I always have to double check to make sure I didn't miss a quarter or something. Thanks Artem.

  • Scott Warner

    A border on the text box would be nice, its not entirely clear without it

    • http://www.androidpolice.com/ Artem Russakovskii

      Yeah, we'll style it a bit as soon as the designer gets to it. And add some spiffy graphics.

      • Scott Warner

        I expect fireworks. Or

        • Arthur Dent

          or GTFO

          • denisu

            searching or on google is too good to pass up ;)

  • Fatal1ty_93_RUS

    Aw, doesn't really work with 4.4.3 though :P

    The approx date has already expired lol

    • http://www.androidpolice.com/ Artem Russakovskii

      Why, the build date has to be in the past, and that's when KTU84F was built?

  • http://www.androidpolice.com/ Shawn De Cesari

    The guy that wrote this must be super duper smart and stuff.

    • http://www.androidpolice.com/ Artem Russakovskii

      I hear he's got a PhD from XDA University.

      • http://google.com/+derekross Derek Ross


        Click here to buy me a beer!

        • http://www.androidpolice.com/ Shawn De Cesari

          Screw beer. Click here to buy me vodka!

      • SuyashSrijan

        If AP can provide me the script source, I can turn it into an Android app :-) I am an experienced developer!

  • http://techdissected.com/ Nick Schiwy

    That can't be right:

    • http://www.androidpolice.com/ Artem Russakovskii

      The Moto G builds are weird, I think Motorola uses their own build number system for Moto G/X.

      • http://techdissected.com/ Nick Schiwy

        That makes sense. I was wondering if it was an AOSP thing. Still a very cool tool. Good idea, guys!

    • Venkatesh Subramanyam

      WTF... 2009 in Kitkat... :P

  • Steve Secor

    But it's more fun to do it manually!

  • Michael J Carroll

    They better think of some new build codes if they want to make builds beyond July 8, 2015.

  • darkdude1


    1) Hopefully this is parsing a text file of some description and not a database (imho using a database would be wasteful)

    2) Perhaps provide a table instead? Then you can use the input to filter the table on the fly, would seem more useful perhaps?

    Other than that, it could be quite useful.

    • http://ignaciozippy.com/ Ignacio Zippy

      It's a parser. Try something like "CRZ99"

      • darkdude1

        Yeah, that makes more sense actually :)

        • http://ignaciozippy.com/ Ignacio Zippy

          It ignores the second letter. It will spit "Jelly Bean 4.1/4.2/4.3" for any "Jxxnn" combination, for example.

          (JR and JZ are 4.1.1 and 4.1.2; JO and JD are 4.2.1 and 4.2.2; JW, JL and JS are 4.3.)

  • Brandon Giesing

    Do I spy a new Android police logo?

  • hp420

    So what will happen to the quarter code when they pass Z in Q2 next year?

  • Jasper Guerrero

    Christmas and it's still Kitkat. Disappointed.

  • Thomas Cai Jinzhan

    KOT49H/Kit Kat...

  • RonD45

    Where's the app?

  • jeremy green

    JZO54K. 4.1.2----JELLYBEAN