Jpeg dimensions do not fit A4?

Hi everyone,

I draw a rectangle of 297 mm length and 210 mm width( dimensions of an A4) as seen in the figure below.

And I save this as a Jpeg choosing A4 ( landscape) as the page format. However the saved image is as shown below.

As you can see, the rectangle although being the size of an A4 paper covers a small area in the image. The problem is that I want this rectangle to coincide with the edges of the image. Is there anyone who can help me with this?

SolidworksSketching