There are approximately 48.988 kilograms in 7 stone 9 pounds.

1 stone is equal to 14 pounds. So, 7 stone is equal to 7 x 14 = 98 pounds. 98 pounds plus 9 pounds is 107 pounds. 1 pound is equal to approximately 0.45359 kilograms. So, 107 pounds is equal to 107 x 0.45359 = 48.988 kilograms (approximately).