Some office furniture comes equipped with caster wheels, which attach to the bottom to allow for ease of movement. Most modern caster wheels are able to turn and roll independently in any direction, making them very convenient for office chairs. If a caster wheel breaks, it may be replaced, without having to buy a new chair. Most caster wheels come in standard sizes and are available at many office supply and hardware stores. Chair casters have easy-to-remove stems for replacement.
Flip the chair on its side and remove the old broken caster wheel. This will require unscrewing it from the bracket, if it has a threaded stem, or popping it out with a screwdriver, if it is a quick release type.
Measure the stem size of the old caster wheel with a caliper and measuring tape, or look to see if the size is printed on the stem. There will be a diameter size, such as 7/16 inch, as well as a stem length, such as 1 inch.
Buy a replacement wheel of the same size. If you are unable to locate the one that you need at an office supply or hardware store, order one from the manufacturer, if possible.
Place the new caster wheel into the old bracket or opening in the chair with the same method that you used to remove the old one. If it has a threaded stem, screw the new one into the threads. If you had to pop it out with a screwdriver, you should be able to push the new one in with just your hand.
If you are unsure of the size of your caster wheel, remove the old one and take it with you to the store to compare with other wheels. Caster wheels come in a variety of options, which allows you to replace all four with a different look, if you choose.
If removing the old caster wheel with a screwdriver, pull it up away from your face to avoid hitting yourself in the eye. As you push in the new caster wheel, keep your fingers and skin clear of the opening or you could get pinched.