• Original Length: 9 reels, 4189 m = 183:44 min (20 frames per second/fps); 167:02 min (22 fps); 153:06 min (24 fps); 146:59 min (25 fps)
• 1927 cut version: 3241 m = 142:09 min (20 fps); 129:14 min (22 fps); 118:27 min (24 fps); 113:43 min (25 fps)
• 1987 restored version: 3150 m = 138:09 min (20 fps); 125:36 min (22 fps); 110:32 min (24 fps); 110:32 min (25 fps)
• 2001 restored version: 7 reels, 3370,5 m = 147:50 min (20 fps); 134:23 min (22 fps); 123:11 min (24 fps); 118:16 min (25 fps)
I don't know what most of that jibberish means, but I think that different parts of the movie are recorded at different speeds (animation vs live action,) and then the resulting film had to be played back at one contstant speed, so you end up with running times all over the place.
You might want to peruse that site.. click on DVD comparisons on the left. There are three different metropolis DVD reviews on there, comparing quite a few releases this public domain movie has seen.
--bdev