When men become too aroused, their organ will bulge and condom will stretch a little to accommodate the increase in size of the organ. It is estimated that an average condom will stretch upto 14% from its normal size to accommodate bulging male organ. Upto 20% condom stretch is considered normal and within safe limit. Needless to say that condom will break if it is stretched beyond that.
The stretchability of a condom is dependent upon its thickness of the material, type of material, freshness of the product, amount of lubrication and type of lubrication used. Ideally, one should choose a condom size with a girth size that is slightly smaller than the organ size.
Example: If the circumference of a penis is4.2 inches, you should choose a condom with4 inches circumference.