Yep, what MGM said is right the chart looks like it was designed for knitting in stockinette stitch. That has a lower height to width than does crochet. You might try a lighter weight yarn with a smaller hook combined with two SC stitches per block on the chart.
Another option would be to run the image through a chart maker web site. I know I've seen some listed here in the forum but I didn't book mark them or the threads in which they were mentioned.