|Inputs (868,000)||Outputs (1,447,600)|
1,400 × Wool (868,000)
1,400 × Ball of wool (1,447,600)
The best possible method is to use the spinning wheel on the 1st floor[UK]2nd floor[US] of Lumbridge Castle, and to bank on the 2nd floor[UK]3rd floor[US]. A full load of 28 wool takes approximately 50 seconds to convert into ball of wool. Travel and banking time is ~20 seconds in between loads. You should use a preset with wool in your inventory to speed up the process.
This money making method can be combined with another method involving shearing sheep for wool. You can find that method by clicking here.