I suggest 20x20 or about the size of a garage. Depends on if you get a long arm, maybe a smaller sit down machine like the Babylock Tiara will work for you. Think about the future and things you might want to try like machine embroidery, they take up a lot of space and so does all the stuff you need to embroider. Also, how old you are, how long do you think you can continue to sew and quilt. How is your health and do you have any physical limitations like arthritic hands, mobility issues etc.