Basics

• The basic interior door slab is 80 inches high. Widths vary greatly, depending on usage. The most common interior door width is 32 inches. Closet doors may be as narrow as 20 inches or as wide as 48 inches.
  
  

Requirements

• The Americans With Disability Act, passed into law by the U.S. Congress in 1990, dictates certain standard architectural requirements to serve disabled individuals. To accommodate wheelchairs, doors must be minimum 32 inches clear with an access route of 36 inches.
  
  

Sizing

• Interior door slabs require a rough opening larger than the door itself. Prehung door kits, with the slab preinstalled onto a doorjamb system, are the easiest to install. Most 32-by-80-inch doors require a rough opening of 34 inches by 82 inches.