Studies of penis size show the 'average' erect penis ranges from 5 to 7 inches (13 to 16 cms) with a girth of about 4 inches (10 cms).
An average non-erect penis ranges between 2 to 4 inches (5 to 10 cms). Very few men have longer than average penises when erect.
Research shows soft (flaccid) penises vary in size much more than erect ones do - and it isn't possible to predict from a soft cock what It'll look like when It's hard.
Some guys don't change much between flaccid and erect, others do. Sometimes this is referred to as guys being 'showers' - they're big when soft and don't get much bigger; or 'growers' - they're smaller when soft but then grow a fair bit as they get hard.
You may have seen larger measurements or averages online, but these are either based on flawed or outdated research, or are being used by people who want to make you feel anxious about your body so you'll buy products from them.
Hang on a second though...
Before you reach for the tape measure, it's worth knowing that most sex researchers and therapists don't trust these figures.
The reason? They're based on measurements from laboratory studies where men knew they were participating in research to see how their knobs measured up.
This means guys who were worried about size were less likely to participate, whilst guys who thought they had big schlongs were more than happy to waggle them under researchers noses.
So most researchers, therapists and doctors suspect the 'average' penis size figures obtained in research (and widely quoted) are at least an inch larger than they should be. This is because research on penis size is skewed in favour of men who are happy to be measured.
That's partly why you sometimes see a range of penis sizes given (as I did at the start of this answer) rather than the mean size, which is unreliable. If you really want a mean measurement then probably 5 inches when erect is more likely than 6 or 7 inches.
Modern sexologists argue that we should look at what counts as 'too small' rather than being hung up about average sizes. Anything under 7 cms when erect is considered clinically small for a penis - which means most men measure up just fine.
