Step 1: Select your song
Right click and select Get info
In iTunes, find the song you want to use for your fancy new ringtone. Right-click and select ‘Get Info’.
Step 2: Set a Start and Stop time
Navigate to Options
Once you’re in the info view, navigate along the top to Options and from there you must select both a start and a stop time. After some fiddling around with the track to find where exactly you want it to start, you can trim it down, and then click OK – remember it can’t be longer than 40 seconds.
Tip:You may need to check the Start and Stop time boxes first if they are unchecked.
Step 3: Creating an AAC Version
Convert to AAC Version
Next, right-click again on the track and click on Create AAC Version. This will automatically duplicate the track, and will create the file you will be working with from now on. You’ll notice a difference in the time of the track compared to the original. You’ll probably want to go back to the original file and remove the start and stop times of the song if you want it to return to normal.
Step 4: Converting to a Ringtone
Right-click and choose “Show in Finder”
You next need to locate to file of the track, and to do that you should right-click on the new version, and chose Show in Finder.
The new AAC Version and the original track
Click Use .m4r
Tip: Don’t close this Finder window, you’ll need it again in a few minutes.
Step 5: Deleting the AAC Version
Delete Song
Make sure to keep the file
Go back into iTunes once more, right-click and delete the AAC Version (the shorter duplicate of the original). Click Delete Song and Keep File on the popups.
Step 6: Adding to Tones
Finally, you should go back to Finder and double-click on your ringtone file (.m4r), which should automatically copy it to the Tones section of your iTunes library.
Your ringtone should now show up in the Tones section
Done ;-)