This varies a lot depending on body shape and grip width, since a "standard bench width" has quite a range, and "close-grip" width also has quite a range.
For me, I believe the ratio is about 80-90%, though I've never tested close-grip bench maxes, nor do I intend to. Standard bench width is with pinkies just inside the ring, and close-grip is with index fingers on the smooth part between the knurling. That would put close-grip at 12-16" and standard at 24-28". I may be completely off on the inch measurement, since I don't have a bar or ruler on me, but the bar-relative measurements should be accurate.
|