Oh, waaaay too small. I'd refold that sheet to 8x10 and then also try 9x11 or 9x12 just to see what that looks like. Tell your DH that 'sufficient' is not a word in my vocabulary!

I would say 9 x 12 anyway. The front legs of seating pieces should be on the rug.

I'd say at least a 9 by 12 which is what we have in our Gentleman's Parlor and it's only 18 ft square.

Dear Danielle's husband,

Not only is a 5-8 rug too small for this room, but it will also look pretty silly. It will be barely visible once you put a coffee table on it. I am sure you are very talented at many things, but it seems that interior design isn't one of them! Please listen to your wife ...

What Pal said.

10 by 14 or larger, even a 9 by 12 will be too small.

I believe you're right about that- 10x14 at least to get all the front legs on it.

I was going to say 9 x 12 but measure and mark with painters tape. I personally like having at least 1-2 feet under the furniture (if not more). I have a loveseat, sofa, and recliner so I measured to make sure that our feet are on the rug when sitting. I really, really dislike a rug that "ends" directly in front of a seating.

Our family room is 18x24 and we also have large furniture, but a sectional rather than individual pieces. I wanted to be sure to avoid the tiny island of rug surrounded by furniture you see when you have a rug too small for a space. I started out thinking a 8x10 would work, but it would have been lost. 9x12 was the bare minimum, but then it would have been completely under the sectional with only 12" showing along the front. I ended up having a remnant custom cut and bound to 10x14.
The larger rug creates a cozy grouping in the room without crowding. The entire sectional and end table fit. I could have gone a little larger, but there wasn't enough remnant. I will eventually add a long console table behind the side facing the kitchen. There is a a chair and ottoman set which aren't on the rug at all. That can be ok too. Not every piece of furniture needs to be on the rug.