You don't really need a chart. You can use it or the exact formula, or you can just use the shortcut formula which is...
Heart Girth X 10 - 200 = weight in lbs.
This will give you the estimate within 2 lbs of the precise formula up to something like 300 lbs.
However, a chart is found here along with the exact formula...http://www.thepigsite.com/articles/1106/use-heart-girth-to-estimate-the-weight-of-finishing-pigs
So according to them, 48" gives you 282 lbs, but the shortcut says 280. Given that it is just an estimate, it is pretty darned close without the extra calculations.
Where folks seems to get into trouble using the method is by NOT getting the actual minimal circumference directly behind the front lets. They get A circumference, but not the minimal circumference.