Sofa/Couch/Easy Chair. Look at the seat height versus your sitting needs. Consider Your Family's Height. People above 6'2" may find it uncomfortable to sit on couches narrower than 23 inches deep, while petite individuals will likely have to deal with dangling feet and poor back support from a couch any deeper than 22 inches. How to Choose the Right Sofa Depth. Meanwhile, a shallow seat usually has a depth between 31” and 40”, which offers an upright seated position that puts your feet on the floor and supports your back. F Slant the back up to 5° for a formal chair and up to 15° for a casual chair. Maybe you're designing something a little loungier, like a sofa or easy chair. A feature story in Futon Life (wow, there really is a magazine for everything) provides some basic figures for both level-bottom and tilted-bottom reclining. This stops people sliding forwards when they lean back and maintains the ideal 100 degree angle for lounging... Michaels last point is extremely good advice. This allows someone on the sofa to lean back or to lay down comfortably across it. I … Find the Sofa Best for You. If the sofa height is not appropriate for a person’s … Now, the back . E To give lower-back support without interfering with the shoulders, plan for a back height of 12–16" above the seat for a casual chair and 20" (typical) for a formal chair. Couch depth is among the primary reasons why a one size couch doesn't fit all. 15 degrees is good for the back angle, BUT you should also slope the seat base down towards the back 5 degrees also.