There is no more basic piece of gym equipment than the barbell, which is (need it be said?) a long metal rod, usually with weights attached to each end. Simple as it may be, the barbell is the cornerstone of many primary upper body exercises, including biceps curls, military presses and bench presses.
As you may have noticed, barbells do come in different sizes, with the two main versions being the the full-sized regulation Olympic bar and the so-called mid-width bar.
The two biggest differences: Olympic bars in commercial gyms can usually bear as much as 500 pounds (competition-grade bars may bear up to 1,000 pounds). On the other hand, the typical mid-width bar's capacity is usually 200 pounds. Also, full-length bars' greater length allows for a wider grip than mid-width bars.
The Olympic Barbell
As its name suggests, the Olympic barbell is the version used in Olympic weightlifting competition. It's made according to the specifications the International Weightlifting Federation (IFA) and is longer and heavier than mid-width barbells or those made for home use.
The specifications are somewhat different for men and women, though most Olympic barbells found in gyms are most likely to be made to men's specifications.
According to the IFA, the men's barbell is 2,200 millimeters or just over 7 feet long and weighs 20 kilograms, or about 45 pounds. The center of the bar is 1,310 mm long (about 55 inches) and the end sleeves at each end where the weights fit are about 415 millimeters or about 16 inches and a bit thicker in diameter than the center of the bar, which is about an inch in diameter.
The women's version is slightly lighter and smaller, weighing in at about 15 kilograms or 33 pounds, and is 2,010 millimeters, or 79 inches in length. The center of the bar is 1,310 millimeters or 51 inches in length and the sleeves are 320 millimeters or 12.5 inches.
The women's bar is a tad smaller than an inch in diameter. Most gyms usually provide standard Olympic bars in bench press and squat racks.
Because mid-width bars are designed mainly for home gyms, their specifications aren't standardized the way Olympic bars are. They're usually 6 feet long but may be as short as 5 feet, and their weight can vary from one manufacturer to the next.
Their considerably lighter weight probably won't contribute much to the load you press, but their significantly lower price won't bear down on your wallet so much either.
For a basic fitness-driven workout, quality mid-width barbells may be easier to manage for the beginner and less-ambitious lifter. Group classes including RIP and BodyPump use these mid-width -- sometimes called "standard" barbells.