Dimensions of Columns

Hello, I have several pages - both blog articles and static pages - on my site and to make sure that my images are cleanly flush with the text I would like to find out what the width in pixels is of the columns that host my content. I am using both the two column with the copy on the left and no sidebar layouts throughout the site. Also, is there anyway to edit the width of the columns, either sidebar or content column?   Thanks, Abbott