I don't know for sure how accurate it is. I had a yorkie that accoring to the chart should be between 3 1/2 and 4 lbs. She tragically died at 5 mos. so I do not know how accurate the chart is. She was following the chart pretty close though. I do have a pup that I am keeping out of my litter and I have been following her weight on the chart so I will see if it holds true..