minSdk, targetSdk, compileSdk

Three numbers, three different jobs

Open app/build.gradle.kts in any Android project and you find this:

1compileSdk = 35
2minSdk = 26
3targetSdk = 35

Three settings. Two of them are the same number. All three contain the letters "sdk". They are almost universally misunderstood, and getting them muddled produces errors that seem to have nothing to do with the thing you changed.

Here is the whole lesson in three lines. Everything else is elaboration.

Where they live

API levels

Before going further: Android versions have names and numbers, and code always uses the number. An API level is just a counter that goes up with each release.

So minSdk = 26 means "Android 8.0 Oreo and up", and compileSdk = 35 means "the Android 15 library".

compileSdk — what you may type

compileSdk picks which version of the Android code library the compiler checks your code against. That is its entire job.

It is a build-time setting. It is not written into the APK. It does not appear in the manifest. No phone ever sees it.

Two consequences that beginners find surprising:

• Compiling against 35 does not mean your app needs Android 15. It only means you were allowed to type function names that exist in Android 15.
• Raising it never breaks old phones. It can, however, produce new warnings, because a newer library knows about more things that are deprecated.

The rule of thumb is simple: use the newest compileSdk your build tools support. For AGP 8.7.3 that is 35, which is what this course uses. Libraries increasingly demand it — if you use a library built against 35 while you are on 34, the build stops before it starts.

minSdk — who may install

minSdk is a gate. Google Play will not offer your app to a phone below it, and a direct install is refused outright with INSTALL_FAILED_OLDER_SDK.

The trade-off is real and goes both ways.

Lower minSdk reaches more phones — but every function newer than that level becomes a problem you have to handle by hand. Type one and the build tools stop you:

Field requires API level 33 (current min is 26)

The fix is a version check at run time:

1val v = Build.VERSION.SDK_INT
2if (v >= Build.VERSION_CODES.TIRAMISU) {
3  // Only runs on Android 13 and newer.
4  askForNotificationPermission()
5}

Inside that if, the tools relax, because they can prove the code cannot run on an older phone.

Higher minSdk means fewer of those checks, at the cost of leaving people behind.

Why this course uses 26

minSdk = 26 covers roughly 95% of Android phones in use, and it buys three specific things:

• Java's modern date and time classes work without desugaring — an extra build step that would slow every build on your phone.
• Adaptive icons are supported, so Lesson 6.1 can draw a proper modern icon.
• Notification channels exist, which Focus Flow needs in Lesson 5.17.

Every one of those would otherwise be an if and a fallback. Choosing 26 removes them all.

targetSdk — the promise

This is the one that genuinely confuses people, because it does nothing at build time. It is read by Android itself, at run time, on the user's phone.

Each Android release changes some behaviour in a way that could break existing apps. Rather than breaking them, Android checks your targetSdk and asks: does this app claim to know about this change?

• If your targetSdk is at or above that release, you get the new behaviour.
• If it is lower, Android quietly keeps the old behaviour for you.

That is why targetSdk is a promise rather than a request. You are saying: I have tested on this version and I accept its rules.

Three concrete examples, all real:

That last one catches people out badly. Raise targetSdk to 35, and a title that used to sit neatly below the clock is suddenly behind it. Nothing failed; you simply took on a new responsibility.

The rule that ties them together

minSdk  <=  targetSdk  <=  compileSdk

You cannot promise to behave on a version you were not allowed to compile against. You cannot target something older than your own minimum. In practice almost every app sets targetSdk and compileSdk to the same, newest number, and minSdk as low as it can bear.