Standard bar height for a bar built in the United States is 42 inches. That is the standard heigh regardless of whether you live in Texas or Vermont. 42 inches converts to 106.68 cm for our Metric friends. If you are making furniture in Italy or China and you plan to ship to the United States, you should be aware of our standard heights.
This is the perfect height for a bar stool is 30 inches tall. The back can be taller and ofter you see the back height going anywhere from 42to48 inches. Be aware of back height if you plan to push your bar stools under something. You want 12 inches of clearance between the top of the bar stool and the top of the bar. If you are much taller than the average person and you really prefer taller bar stools, you could consider making your home bar taller but for public spaces, there really is no reason to break the standard. If you are incorporating high boy tables, you will need table bases around 40.5 inches so that it is 42 inches when you add the table.
For homes that are building a counter, you may want to do 42 inches but that will be kind of high and may block your view of the rest of the room from the kitchen. Most kitchens use 36 inch counters and those pair well with 24 inch counter stools. There are also counters at diners and grills that have 36 inch counters. They will typically use a 24 inch stool.
The last standard height is 30 inches which is the standard height of a table and pairs well with a standard chair that has an 18 inch seat height. You can also used bold down seating and make your bolt down chair with an 18 inch seat height.
The only thing smaller would be a children's table where there is no standard and there is also no longer a need for 12 inches of clearance for legs.
Using a 30 inch bar stool is safer than using a taller bar stool, With the standard being 30 inches, people are used to 30 inches and when they get off a bar stool they about know where the ground is going to be. If you use a 34 inch bar stool, you may have a few extra people stumble when trying to get off the stool.