A blue whale can weigh as much as 200 short tons (400,000 lbs). An adult blue whale can weigh up to around 180 metric tons (400,000lbs). A blue whale can weigh as much as 200 short tons (400,000 lbs).An adult blue whale can weigh up to around 180 metric tons (400,000lbs). A blue whale calve can weigh up to 2.7 metric tons (almost 6000lbs)