Not as risqué as it might sound, the stripping ratio does NOT refer to the propensity of Jakarta’s nightclub dancers to throw off their clothes but instead to the relative amount of overburden (waste) required to be moved to access coal seams.
The definition is:
Total overburden (waste) removed / coal mined
Hence if a coalminer has a stripping ratio of 8x, this means that eight times more overburden (waste) is removed in relation to the amount of coal mined.
When coal prices are low, coalminers will typically seek to achieve a low stripping ratio – as removing waste is a costly business. If the stripping ratio is very high, above say 12x, it may mean that the coal is uneconomic to mine.