Thank you for your inquiry to Allen Construction. I am assuming your question refers to the bar at the end of the island (with the two stools). The width of the bar section is 48 inches. The area for knees under the counter top is approximately 15 - 16 inches (difficult to tell from the on-line plans as that dimension is not given and I had to guesstimate based on other measurements.)
I hope that provides you the information you were looking for.
Allen Construction