mtho gang

མཐོ་གང
span from thumb to middle finger extended [IW]

span, span in length [JV]

one finger span; The span from the tip of the thumb (mthe bong gi rtse) to the tip of the middle finger (gung mo'i rtse) is called one finger span (mtho gang). Twelve fingers (sor bcu gnyis) are one finger span (mtho gang) [RY]

span from thumb to middle finger extended [mtheb rtse nas gong mdzub kyi rtse'i bar tshad de dang sor bcu gnyis gzhal ba gnyis don gcig] [IW]