I downloaded Android Studio and installed it. The installer said:-
Android Studio => ( 500 MB )
Android SDK => ( 2.3 GB )
Android Studio installer is actually an "Android SDK Installer" along with a sometimes useful tool called "Android Studio".
Most importantly:- Android Studio Installer will not just install the SDK. It will also:-
Things which you will have to do manually if you install the SDK from its zip file.
Just take it easy. Install the Android Studio.
****************************** Edit ******************************
So, being inspired by the responses in the comments I would like to update my answer.
The update is that only (and only) if 500MB of hard disk space does not matter much to you than you should go for Android Studio otherwise other answers would be better for you.
Android Studio worked for me as I had a 1TB hard disk which is 2000 times 500MB.
Also, note: that RAM sizse should not a restriction for you as you would not even be running Android Studio.
I came to this solution as I was myself stuck in this problem. I tried other answers but for some reason (maybe my in-competencies) they did not work for me. I decided to go for Android Studio and realized that it was merely 18% of the total installation and SDK was 82% of it. While I used to think otherwise. I am not deleting the answers inspite of negative rating as the answer worked for me. I might work for someone elese with a 1 TB hard disk (which is pretty common these days).