If you weigh 105lbs and are 5 foot 1 how old should you be?

Your age doesn't matter. Your age doesn't tell you what weight you should be unless your a toddler or younger. You are actually at your proper weight :)

Here is the chart:

5.00 ft = 100 lbs

5.01 ft = 105 lbs

5.02 ft = 110 lbs

5.03 ft = 115 lbs

5.04 ft = 120 lbs

5.05 ft = 125 lbs

5.06 ft = 130 lbs

5.07 ft = 135 lbs

5.08 ft = 140 lbs

5.09 ft = 145 lbs

5.08 ft = 150 lbs

5.07 ft = 155 lbs

5.08 ft = 160 lbs

5.09 ft = 165 lbs

5.10 ft = 170 lbs

5.11 ft = 175 lbs

5.12 ft = 180 lbs

... and so on and so forth.