Android heap size on different phones/devices and OS versions

Does anyone know if the heap size on Android phones is a constant value according to what is set in the OS version or if this is a setting which the phone producers can decide on?

Is the heap size proportional to the amount of RAM on the phone?

I've only found articles where people say that the heap size of an application is 16M. However, these articles are a bit old. From what I see, as an example, heap sizes vary from around 20M up to 24M on one specific model. This phone has 768M of RAM.

Some more device info extracted from build.prop files (adb -d pull /system/build.prop):

Phones (Android Version):

• HTC Wildfire (2.2.1) = 16MB
• HTC Wildfire S (2.3.5) = 20MB
• HTC Salsa (2.3.3) = 20MB
• HTC Desire (2.3.3) = 32MB
• HTC Desire S (2.3.5) = 32MB
• Sprd - Richview - S111 (2.3.5) = 32MB
• Samsung Galaxy S GT-I9000 (2.2) = 48MB
• Samsung Galaxy R GT-I9103 (2.3.5) = 64MB
• Samsung Galaxy Y GT-S5360 (2.3.5) = 64MB
• Samsung Galaxy Note N7000 (4.1.2) = heapstartsize=8m, heapgrowthlimit=64m, heapsize=256m
• Samsung Galaxy S3 GT-I9300 (4.3, xhpdi) = 8/64/256MB
• Samsung Galaxy S4 GT-I9505 (4.4, xxhpdi) = 8/128/512MB
• Google Galaxy Nexus (4.3) = 8/96/256MB
• Google Nexus 4 (4.4, xhdpi) = 8/192/512MB
• Google Nexus 5 (4.4, xxhdpi) = 8/192/512MB
• Samsung Galaxy S6 SM-G920W8 (7.0) = 8/256/512MB

Tablets (Android Version):

• Samsung Galaxy Tab GT-P1000 (2.2) = 48MB
• Samsung Galaxy Tab 8.9 GT-P7300 (3.2) = 5/64/288MB
• Samsung Galaxy Tab 10.1 GT-P7500 (3.2) = 5/64/288MB
• Samsung Galaxy Tab 3 10.1 GT-P5200 (4.2, mdpi) = 8/96/256MB
• Acer Iconia A500 (3.2.1) = 5/48/256MB
• Kindle Fire HD 7" (4.0.3) = 5/48/256MB
• Asus Transformer Prime TF201 (4.1.1) = 5/48/256MB
• Nexus 10 (4.4.3) 16/192/512 MB

> Does anyone know if the heap size on Android phones is a constant value according to what is set in the OS version or if this is a setting which the phone producers can decide on?

Technically, it is a setting which the phone producers can decide on. Android is open source. I do not recall the Compatibility Definition Document spelling out heap size requirements, though I haven't looked recently.

> Is the heap size proportional to the amount of RAM on the phone?

No, it tends to be based more on screen resolution, as higher-resolution screens tend to want to manipulate larger bitmaps, so Google makes heap size recommendations that, hopefully, device manufacturers will abide by.

> I've only found articles where people say that the heap size of an application is 16M.

Searching StackOverflow on [android] "heap size" turns up this answer.

Not only phone producers, but anyone who creates a version of the Android OS, can specify the maximum allowed heap size, based upon the specific requirements of their devices. Some Android roots, such as CyanogenMod, even allow the user to select the heap size herself as a setting.

You can detect the maximum allowed heap size using the method

Runtime.getRuntime().maxMemory();

Additional information on this topic is available here.

If your app normally needs more than 16MB of heap, a suggested approach would be to set a minimum OS version level in your manifest that ensures that the overwhelming majority of those downloading your app will have at least the amount that you need, and then find a way to degrade your functionality gracefully in a way that reduces your heap requirements as needed, down to a base level of 16MB, for the small number of users with less than your optimal amount of heap who fall through that sieve.

Here are some figures showing the association of phone RAM with OS version (based on current, not original, OS). I believe that a phone having at least 1GB of RAM will almost always have more than 16MB of heap. Note that the percentages here are for the number of phone models supporting the indicated memory, not total phones in use, which may be quite skewed toward certain models. These numbers were obtained by plugging inputs into the following phone finder (which includes 1500 Android phone models) and so are only ballpark figures: http://www.gsmarena.com/search.php3

Percentage of phone models having at least 1GB of RAM, by current OS version (not version at launch):

Phones running         Percent of models having at least 1GB of RAM   Percentage of all models
4.4 and up             100 percent                                    1.5
4.3 and up             100 percent                                    2.9
4.2.x and up           74 percent                                     18.7
4.1.x and up           71 percent                                     37
4.0 and up             62 percent                                     60
2.3.x and up           57 percent                                     71
2.2 and up             44 percent                                     93
2.1 and up             44 percent                                     97
ALL OS VERSIONS:       41.5 percent                                   100

You should be able to check the max vm heapsize using:

getprop dalvik.vm.heapsize

at Android terminal (connectbot or adb shell etc). It is possible to remount read-write and set the heap size in the build.prop file as well. (Make sure you have recovery installed so you can re-set it if you accidentally make it too small, it won't boot up).

The "VM Budget" that an application is allowed to use varies from device to device. Tablets typically permit a larger budget than phones.

Here are some VM budget sizes I've found for various devices.

• G1 = 16 Mb
• Droid = 24 Mb
• Nexus One = 32 Mb
• Xoom = 48 Mb
• GalaxyTab = 64 Mb.

(Note: if you've found differently, let me know)

There is actually a defined minimum application memory that depends on the screen size and density:

> Mobile devices typically have constrained system resources. Android > devices can have as little as 16MB of memory available to a single > application. The Android Compatibility Definition Document (CDD), > Section 3.7. Virtual Machine Compatibility gives the required minimum > application memory for various screen sizes and densities. > Applications should be optimized to perform under this minimum memory > limit. However, keep in mind many devices are configured with higher > limits.

Quoted from: http://developer.android.com/training/displaying-bitmaps/index.html

But as others have stated, each device manufacturer decide the actual value for the device, so it could be greater than this (but not smaller).

The mentioned Compatibility Definition Document (CDD) listing the minimum requirements for each version of android: https://source.android.com/compatibility/cdd.html

For the latest version of Android there is a html verison available, and we can directly link to the runtime memory section there: https://source.android.com/compatibility/android-cdd.html#3_7_runtime_compatibility

For Android 2.3:

> Device implementations with screens classified as medium- or > low-density MUST configure Dalvik to allocate at least 16MB of memory > to each application. Device implementations with screens classified as > high-density or extra-high-density MUST configure Dalvik to allocate > at least 24MB of memory to each application. Note that device > implementations MAY allocate more memory than these figures.

For the modern versions, there is instead a table where it depends on screen density etc:

For Android 4.2, example row from that table: > small / normal / large size and xhdpi density: 64MB

For Android 6, extract: > small/normal xhdpi: 80MB > > small/normal xxhdpi: 128MB > > small/normal xxxhdpi: 256MB

There is a table for the other Android 2.x, 4.x, 5.x and 6 versions too in those documents (see CDD link above).

Refer to this google link to easily find screen densities etc for specific devices: https://design.google.com/devices/

This data is working for me. Select Emulator Tablet Android TV RAM 1536MB VM HEAP 16MB Internal Storage 800MB Studio -managed 100