I like rugs large enough to slip under the front 1/3 of the seats and extend past the ends of the pieces by a foot or more. Painter's tape on the floor will help you visualize it. If your taped "rug" is not a standard size, then go up one size.

A rug is best sized to the ROOM, not a sectional . Draw the room on paper, measure with a 25 ' tape measure, every wall, window and opening, and note those dimensions. Post it here.

https://www.wikihow.com/Draw-a-Floor-Plan-to-Scale

Since you didn't show us the entire room, I assumed you were interested in a rug to anchor the sectional you showed us. If that is not the case, please be specific.

A rug sized to a sectional is not USUALLY the best rug for the room. That's why you draw the room. Maybe it is.........and maybe not. More info gets you the best answer .

Area rugs, for the most part, come in standard sizes. So as a general rule, you want the largest rug that still allows some of the flooring to show around it between the walls of the space. If you follow that rule, then most likely you should be fine. Most people make the mistake of buying a rug that is too small.

Yes as above............BUT. You can select a broadloom you like, pattern or solid, and very easily have it bound to a perfect size. Broadloom is available in both 12 and fifteen foot widths, making the size and all else virtually limltless options. You aren't restrained to standard selections of 6 x9 , 8 x 10 9 x12 etc.

Just one more reason to measure the room : )