Help please! i don't know when my penis is hard it is about 6in and sometimes its more or less. why is this?

It varies: You're a little above average for a guy, and length will vary depending on how excited you are -- it's not just "on" or "off". You'd be doing yourself a favor to stop measuring it, stop comparing yourself to other guys, reassure yourself you've got what it takes in this department to be a good lover, and work on the rest -- job, social skills, studies, personality, hands, mouth, hygiene. Cheers.

Here are some ...: Have you measure your penis in the same way at the same degree of penile rigidity? Nonetheless, a 6-in penis is a good length for a men. If there has been no functional concern, I would not spend time to figure "such" out. Technically, I'm sure the "different" length results from the variables as mentioned above.