Heap size that can be used in android: largeHeap = "true"

increase heap memory in application

You can increase heap memory in application from API Level11.
Be written as follows in the android developer site.

Return the approximate per-application memory class of the current device when an application is running with a large heap. This is the space available for memory-intensive applications; most applications should not need this amount of memory, and should instead stay with the getMemoryClass() limit. The returned value is in megabytes. This may be the same size as getMemoryClass() on memory constrained devices, or it may be significantly larger on devices with a large amount of available RAM.
The is the size of the application's Dalvik heap if it has specified android:largeHeap="true" in its manifest.

If you want to use large heap, you should write in AndroidManifest.xml.

android:largeHeap="true"

If you want to check heap size on your device, call ActivityManager.getLargeMemoryClass().

ActivityManager am = ((ActivityManager)getSystemService(Activity.ACTIVITY_SERVICE));
int largeMemory = am.getLargeMemoryClass();