How to specify the size of the icon on the Marker in Google Maps V2 Android

The accepted answer is outdated (Resources::getDrawable has been deprecated since API level 22). Here's an updated version:

int height = 100;
int width = 100;
Bitmap b = BitmapFactory.decodeResource(getResources(), R.drawable. marker);
Bitmap smallMarker = Bitmap.createScaledBitmap(b, width, height, false);
BitmapDescriptor smallMarkerIcon = BitmapDescriptorFactory.fromBitmap(smallMarker);

and then apply it in MarkerOption

.icon(smallMarkerIcon)

Currently it's not possible to specify a marker size using MarkerOptions, so your only option is to rescale your Bitmap before setting it as your marker icon.

Creating the scaled Bitmap:

int height = 100;
int width = 100;
BitmapDrawable bitmapdraw = (BitmapDrawable)getResources().getDrawable(R.mipmap.marker);
Bitmap b = bitmapdraw.getBitmap();
Bitmap smallMarker = Bitmap.createScaledBitmap(b, width, height, false);

Using smallMarker as the marker icon:

map.addMarker(new MarkerOptions()
        .position(POSITION)
        .title("Your title")
        .icon(BitmapDescriptorFactory.fromBitmap(smallMarker))
);

Kotlin version I used 0- 9 answer and used it with kotlin

fun generateHomeMarker(context: Context): MarkerOptions {
    return MarkerOptions()
        .icon(BitmapDescriptorFactory.fromBitmap(generateSmallIcon(context)))
}

fun generateSmallIcon(context: Context): Bitmap {
    val height = 100
    val width = 100
    val bitmap = BitmapFactory.decodeResource(context.resources, R.drawable.logo)
    return Bitmap.createScaledBitmap(bitmap, width, height, false)
}