A:
Hello,
the Exterior Dimensions are (WxHxD) 29 7/8" x 17 3/4" x 15 7/8"
Since you only have 30.5" between your cooking surface and your cabinets, it seems that you don't have enough space for an Over-the-Range Microwave. The minimum distance between cook top and cabinet or microwave should be 30".
Since the installation manual is not online please feel free to contact LG Customer Service at (800) 243-0000 or visit the support section of our website at www.LG.com/us/support/ for assistance.
Thank you for your question!