1 ton = 2000 lbs. 1 lb. = 2.204kg Do the math!
First take the weight in pounds and multiply by 453.59. The resulting number is the weight in grams. To convert grams to kilograms, simply divide by 1000. Or, an easier option is to take the weight...
15 stone = 95.25 kg
90 short tons = 81,646.6266 kilograms