User blog comment:- Darkchylde/Dragon Battle 4: Smaug vs. King Ghidorah/@comment-71.29.185.104-20131226024444/@comment-68.224.90.67-20140321192110

In my analisis of both these dragons, I estimate the length of Smaug to be anywhere from 90 meters to 100 meters based on screenshots from the movie. In comparison, Ghidorah from the original series is 150 meters, which means that by comparison, Ghidorah is bigger than Smaug.