You don’t really need the chair but it would be nice to have that and I find my guests never use the dresser in my guest room so we took it out and put a small desk and chair in , it gets used all the time. So I would say 11 x11 is a good size.

In my last house, the guest room was 10.5 by 11 feet and inches, with a very small (four foot) closet. Like Patricia, I removed the unused chest of drawers, and replaced it with a desk and small chair. A queen bed, bookshelf, night table and lamp fit nicely, along with a folding luggage stand.

Are you designing a home? Door and window placement make a difference, too. Try laying out the furniture you'd like to have in the room to make sure you have ample circulation space, and a decent bit of uninterrupted space for the bed wall/headboard.

As a code perspective, the International Residential Code (US) states:

R304.2 Other rooms.

Other habitable rooms shall have a floor area of not less than 70 square feet (6.5 m2).

Exception: Kitchens.

R304.3 Minimum dimensions.

Habitable rooms shall not be less than 7 feet (2134 mm) in any horizontal dimension.

Exception: Kitchens

If it's truly a guest bedroom that won't be used that much, anywhere from 11x11-11x13 would be ok...depending on the size bed you want to use.

How long do you want the guest to stay?

Thank you so much for your input. It is much appreciated. My husband and I are building. Home and the width for the guest room can only be 10 feet, but the length can be 13 to 15 feet. I was nervous that would be too small. Unfortunately, I cannot increase the width.

10 x 13 is plenty. Use the extra 2 feet of that 15 feet available for storage.

The smallest bedroom we have is a 13 x12. I wouldn't go smaller than that. It fits a queen bed and two nightstands, a small tv cabinet. The room has a walk-in closet