Be aware that Magnums, since their introduction in the ’80s, have always tapered down to a “normal” size girth towards the bottom of the shaft — this was true before they were even sold to Trojan’s parent company. Most men can wear “Magnums” without any issue — that’s how they were designed from the get-go — namely to prevent slippage for folks who chose them as an ‘ego boost’.
For actual condom dimensions, here’s a nice quick reference size chart/info (note: it’s sponsored by Undercovercondoms — condom reseller) for major condoms brands. I seem remember there was another online store which gave measurements for base, mid-condom, and “head” area as well as the length but I just can’t remember what it was for the life of me though. If I find it I’ll post a link here..
Additionally, this site gives some great condom size/stretching info, which we could even use as more argument in the whole “average size” debate..
In fact, it’s very interesting how using the information in the above link the IDEAL tension of the condom against the erect penis can be used to extrapolate what the typical penis circumference is.. The results being 4.73” to 4.92” inches.
It just so happens that coincides nicely with the popular LifeStyles Cancun study, which is used here on Mr. Average’s site for building out a nice table of stats (http://www.mraverage.com/stats.htm). Considering that the US condom market alone is worth in excess of $500million I trust that the manufacturers have the size issue pretty dialed in (girth-wise, anyway) — if they didn’t we’d be seeing a much higher failure rate of condoms, complaints about fit, etc. And their condoms would be be leaking market share aside from, well.. You know.
It looks like the studies referenced for condom fit are here, if anyone wants extra credit reading.
http://sti.bmj.com/content/85/2/127.abstract — Penile dimensions and men’s perceptions of condom fit and feel
http://std.sagepub.com/content/9/8/444.abstract — Does penis size influence condom slippage and breakage?