How to Calculate Seat Height

Use the chair height guidelines in Resources if you're building a chair for kids. The age of the child dictates the height of the seat. Most adult seats are built at 18 inches as a common furniture industry practice. In most cases, 18 inches will be too high for most kids younger than 13.

Measure the height of the table or furniture where you want the table to slide into. Use the tape measure to measure the distance from the floor to the bottom of the table. If you want the seat to slide in, you must make the chair smaller than the distance between the floor and the table.

Ask the preference of the person for whom you're building the chair. If building a chair for someone else, ask her for her seat height preference. If she's tall, she might prefer a seat that's taller than the standard 18 inches. Have her sit in taller chairs by possibly taking her to a furniture store and have her sit on different-size seats. Once she chooses her preferred height, measure the distance from the floor to the seat with the tape measure.

Consider all of the requirements for the seat you're building. If the seat must fit under a table and also needs to be taller than normal, make sure you use the smallest of two numbers. For example, if a seat can be no taller than 24 inches to fit under the table and the maximum comfort for the person on the custom seat is at 26 inches; you must still only build the seat 24 inches. If you build this seat taller than 24 inches, it won't be able to fit inside the table.