That's a fantastic chart! Thanks for posting it. Another thing to remember is that each bird will (roughly) eat 2 pounds of food for each pound that it gains in mass. Using that chart, you see that by week eight, the males will be 7.5 # and the females 5.6 #.
Assuming you've got a straight run and you have roughly half males and half females, you'd expect 12 males and 12 females.
Males total expected weight = 12males x 7.5# per bird = 90 # of bird mass
Females total expected weight= 12 FM x 5.6# per bird = 67.2 # of bird mass
Total poundage of bird mass for you entire flock would be 90 + 67.2= 157.2#
So if the birds eat 2 lbs for each lb they gain, you'd have fed them roughly 314.4 pounds of food during their life. That would mean you're on your 7th 50# bag of food.
How much food have you gone through?
What is the percentage of protein in your food?
Dan
Edit:
I just found this growth chart on Cornish Crosses from Welp Hatchery. It's very informative:
I've heard that Welp Cornish Crosses are another step above the "average" hatchery cornish cross. That said this chart is still a good guide for you. Check out the 63 (9 weeks old) day old chicken's daily intake of feed on the chart. Both Male and female are eating half of pound of food per day! That's 12 pounds of food per day for you're flock, so you'd be going through a 50# bag every 2.5 days roughly.
Mine just turned 7 weeks old today and they take 3 days for a 50# bag so they're right on track according to this chart.