This type of question gets posted on online forums constantly. How much does an olympic bar weigh? Are they all the same weight? How can I tell the difference?
First of all, one reliable way of determining the weight is with a bathroom scale. Just weigh it, and there’s your answer. But sometimes that isn’t practical, such as if you’re at a commercial gym or somewhere else that you would have to go to some serious trouble to get a bathroom scale and the bar in the same room together.
Knowing how much your olympic bar weighs is important so that you know how much you’re actually lifting. If you’re always using the same bar and always will, it doesn’t matter much, because you can record it the same every time. But if you use more than one bar, or work out at different locations, or might at some point in the future, it’s valuable to know the weight of your olympic bar.
The strictest weight specification for an olympic bar is 20kg. This is the international standard for the purpose of competitions. 20kg is the men’s bar and corresponds to 44 lbs. A women’s bar is exactly 15kg or 33lb. There is a tiny amount of room for variability in weight, but it isn’t much, because competitors depend on the bar being the stated weight, when grams/ounces make the difference between winning and losing, or making a new PR.
IPF and IWF specifications for powerlifting and weightlifting bars, respectively, both require 2.5kg collars to be used. So a pair of collars plus a 20kg bar is 25kg. The reason for this again is consistency. If you have lighter collars at home and like them, there’s nothing wrong with that, as long as you know what they weigh. What they want to avoid is competitors having to guess or assume what the collars weigh. What they “usually” weigh isn’t good enough. It has to be guaranteed.
For lower grade equipment, such as economy bars, which are typically included in 300lb weight sets or sold for under $150 individually, the weight is often 45 lbs. Sometimes they will actually be 44 lbs to keep with the 20kg standard. But people have reported such bars weighing less than 40 lbs in some cases. If it’s a cheaper bar and is less than 7ft long, all bets are off. There’s no standard for that.
Specialty bars like curl bars, tricep bars, hex deadlift bars, and others, can also weigh anything conceivable and are usually not calibrated to any particular weight by means of precise machining. They make the bar, figure out what it weighs, and make that model (hopefully) the same every time so it comes out to the same weight. This is in constrast to calibrated bars, which are precisely machined by cutting the length of part of the bar to ensure the weight comes out the same even if the length is a couple millimeters off. This of course requires an extra step and adds to the price of the bar, so calibrating is only done to higher end bars.
Standard bars, or bars with 1″ diameter ends, might weigh anything. They aren’t used in competitions, so nobody really cares about consistency, and no organization has gone to the pointless trouble of creating any kind of specification for them. We’re just lucky they’re all pretty much the same size and fit the same plates.