Been out and measured a few this morning. The baler we used was a fabulous old piece of kit, the only baler we've ever found that we could fit in our field, but its quaintness seems to extend to inconsistency of bale size. Average size seems to be 31 inches X 18 inches X 15 inches ( for those of you born after 1970 that is 79cms X 46cms X 38cms) ( smallest are about an inch smaller each way and some bigger ones a couple of inches bigger. I've never measured a "normal" small bale but my best guess is that ours are approx. 3/4 size