How much should a 14 year old boy weigh at 70 inches?

There is on old saying. 5 feet = 100 pounds. and add 5 pounds for every inch after that. so you are 5'10. 5x10 = 50. 5 feet = 100. so around 150. but it depends on your body structure so dont worry, eat healthy and exercise and you will be perfectly fine :D
Based on the height to weight ratio chart, which is not 100 percent accurate, for boys ranging in age from 14 to 15, the average height is from 63 inches to 66 inches or 5 feet 3 inches to 5 feet 6 inches with a weight of approximately 105 pounds to 125 pounds. On average, a sixteen to 17 year old boy's height range from 67 inches to 70 inches or 5 feet 7 inches to 5 feet 10 inches with a weight of approximately 130 pounds to 150 pounds. The average weight for a 14-year-old boy who is 5 feet 10 inches would be approximately 115 pounds to 150 pounds.