These sizes come standard 24″ high, however; when a cushion is applied to the seat, it is generally 26″ high which is also a standard height for a 36″ high counter.
It's important to have 10-12 inches between seat and counter top. When sitting in these, your feet generally touch the floor. For shorter persons, the ring or foot rest can be a support.
These are usually used for bars or high counters: 41-42″ high. The height of stool should be approximately 30″ (from seat to floor). The foot rest is usually the same distance from the floor as the counter height stools. The foot rest is the main support for the feet. The legs or base for this height is taller than the counter height.
32″ height is also a comfortable height for a stool to put with a 41-42″ high counter.
A 34″ stool is generally used around pool tables for a better view of the game. It is also used when a bar is higher than standard height 44″ and higher. This stool is a bit harder getting into because of its height, but the footrest or arms can be used for support when climbing in.
An adjustable height stool usually has a lever beneath the seat and can be adjusted by moving the lever up or down. When the stool is at a 30″ height, you must usually be seated to adjust your height to counter height (24″). To bring the stool back up, exit the stool and then pull the lever up.
Adjustable height stools work well if you have two different height counters and want to switch the stools from one counter to the other.
Usually these type of stools come in contemporary design and in pedestal-based design.
Vanity stools are usually used in front of a vanity sink in a bathroom or a vanity in a bedroom which is generally a little higher than a table (approximately 31-32″ high).
Vanity chairs generally run (from floor to seat) at 17″ to 18″ in height. Some come swivel, some come stationary and are used when a chair is just too low.
18″ high stools, which are usually backless, are great for smaller counters.
This will give you an idea of how many chairs/stools you can fit across. This measurement can help you when deciding if you want stools with arms or no arms.
Measure the area between the counter and any obstructing walls, appliances, or walkways that could hinder the moving in and out motion of your chair.