Cigars 101: Cigar Sizes & Ring Gauge Chart
The size of a cigar, in name, is a nearly meaningless designation, the reason being that the size of a cigar, when determined by a name such as corona or robusto, is not a universal standard. In other words, one company's corona is another company's churchill even though both measure the exact same length and ring gauge. Once you understand this, most of the confusion regarding cigar size disappears.
There are, however, "classic" measurements for cigars that most cigar makers attempt to follow, But remember, just because a cigar is 7 inches in length with a 48 ring gauge doesn't necessarily mean that the manufacturer will designate that cigar as a churchill. All you really have to know is that cigars are categorized by length and ring gauge which is a fraction of an inch measured in 64ths. A cigar with a 52 ring gauge, for example, measures 52/64ths of an inch in diameter.