How much does a barbell weigh? If you had asked me that question 10 years ago I would have had to guess. If you asked me three or four years ago I might have said “45 lbs, duh.”
If you asked me today, I would say “It depends.”
Typically, an Olympic barbell with rotating sleeves will weigh 45 lbs. But even at this standard there can be small discrepancies. The gym where I used to teach had a very sensitive scale.
One day, on a whim, I weighed a few of the barbells. A couple were exactly at 45 lbs. Others differed by fractions of a pound, and one was actually 44.1.
Is this a huge difference? It depends. If you don’t care, then no. If you’re competing at an elite level and the distance you can place between you and your competitor might be a pound, then yes, it would matter. Train how you will compete, right?
This same gym also had barbells for women that weighed anywhere from 14.5 lbs to 15.7. They looked just like the heavier O bars, and if you were not an experienced weight lifter you might have gotten them confused if in a hurry–until the bar snapped in half once you started deadlifting.
There are also thick barbells and axles that have diameters from 2-3″. They can weight anywhere from 30 lbs to 75. Of course, they could weigh as much as someone wanted them to, if they were willing to scour the earth for heavier metals and insane fabricators.
When most people ask, they seem to be thinking in terms of an O bar that they would find at the local Gold’s Gym. But be aware that there are differences. If you really want to know for yourself, I recommend weighing your bar.