For your dining space, start with an 8' x 10' or an 8' x 11' rug as a baseline. It easily fits a standard table and six chairs, ensuring chairs stay on the rug when pulled out and preserving a spacious look.
In living areas with hard floors, the 8' x 10' and 8'X10' dimension are favorite, nestling under a sofa's front legs and accommodating chair legs for a cozy setup. For more expansive spaces, especially those with higher ceilings, think 9x12 or 10x14.