How long is used when you need to ask someone about the time they are gonna need. Eg. How long does it take you to get ready in the morning?

If you’re talking about people, use tall

it usually helps to finish the sentence. how long ....is your belt sounds good, but how high is your belt, not so much lol. some more examples: how long is the road? how high is the building? how tall is your friend?

Hi Sara, I'll try to explain you the differences between those three questions. 1)"How long" is used for asking about the length of something it can be concrete or abstract things. Example: -How long anaconda's body in cm? (Concrete) -How long this relationship would be lasted? (Abstract) 2)"How high" is used for asking about the height, but this is not for human body. It is more for building, mountain, hill, or plane (or bird) altitude. Example: -How high the elevation of Mount Everest in meter? -How high the average plane altitude? 3)"How tall" is used for asking about someone's height (means this question is exclusively used for human only). Example: How tall is Michael Jordan? I hope this helps :)

"Tall" is a measurement of a thing or person or any other entity, or even of an idea. To say a person is "tall" means he has a measurement (in the vertical direction) that is significant. To call a story a "tall tale" means that it measures large on the scale of imagination. (By being not believable). To say a person is "tall" means their vertical measure is large, but even if the person is lying down (horizonally) you would still say the person is tall because their tallness is a property of the person himself, not a description of where he is compared to other things. "High", on the other hand is a relative measure. A thing cannot be "high" in and of itself. A person lying on the ground cannot be high. A bird is high if it is flying but it is not high if it is on the ground. "Highness" is not a property of the bird itself, but rather how it is located relative to other things. If you order me to jump, I can reply "How high do you want me to jump?" I cannot ask "how tall do you want me to jump?" It would make no sense because it is not clear what thing would be tall. Tallness needs to describe something. But it makes sense to talk about high I can jump because it makes a relative comparison between this particular jump and all possible jumps.