Not everyone is the same size, but furniture typically is.
For example, the height and width of the seat of a kitchen or dining chair is usually around 18 inches, and the back ranges from 30 to 48 inches high. A kitchen or dining table is about 30 inches high.
Of course, there are plenty of variances in sizes of what you may find in your home or in furniture stores, but these figures are good basic guideline dimensions that can get you started when planning to build a set of chairs and table.
However, if you are looking to build a table and chair set for children of specific ages, you might want to consider this list of sizes for chairs and tables for various age ranges.
Age 5-6
Chair
Seat height: 10 1/2 inches
Seat width: 11 inches
Back height: 20 1/2 inches
Table
Height: 17 1/2 inches
Age 7-8
Chair
Seat height: 11 1/2 inches
Seat width: 12 inches
Back height: 21 3/4 inches
Table
Height: 19 inches
Age 9-11
Chair
Seat height: 13 inches
Seat width: 14 inches
Back height: 24 inches
Table
Height: 20 3/4 inches
Age 12-15
Chair
Seat height: 16 inches
Seat width: 15 inches
Back height: 29 inches
Table
Height: 25 1/2 inches
We all know that not every 9 year old is the same size, and of course, kids grow quickly. So if you make furniture for your children or grandchildren, it’d be best to size the pieces to last through a broad range of ages.
And certainly, if you’re building furniture for a setting that will have a consistent age range year in and year out, such as a playroom at a church, size them for specific ages.
