Dimensions of 100 kilogram gold box?

Gold has a density of 19.3 so 100 kg has a volume of:

about 100 / 19.3 = 5.18 (dm3)

So a cube weighing 100 kg will have a side the third root of 5.18 ( in decimeters) or 1.73 which is 173 millimeters or about 6.8 inches

(So those movies where they grab bags of gold coins or briefcases full of gold bullion - you know its not real gold!)