[USMA:28094] Phonographic records

[Chimpsarecute]

A discussion came up recently about LPs.  The other person insisted that a 12 inch LP actually measures 12 inches.  So I got out a few of my old ones and measured them with calipers.  I found that the American ones I have all measure in at 302 mm.  Not the almost 305 mm need to be 12 inches.   I also have some German records and they measure exactly 300 mm.  When I place a German one on top of an American one, I can see the German one is slightly smaller and if I run my finger around the edge of the two I can feel the difference.   I also measured some old 78s and found them to be 250 mm and the old 45s to be 173 mm.   I doubt there ever was an ISO or similar standard for records.   I tried researching it on the net, but nothing came up.  I saw constant references to the 12 inches used as a trade name, but no standard defining the 12 inches to be written in stone.   Can anyone here who has old records do a quick check on theirs to see if my measurements agree with yours?  Does anyone have an actual 305 mm record?  Are all of your records consistant in diameter?   It would be real nice if someone from the UK, Canada, Australia, the EU etc would measure theirs and see if they are a real 12 inches or not.   The same for the 45s and 78s too.   And please don't tell me that records are obsolete and it doesn't matter what size they were.   Thanks,   Euric