Why do I compare myself to others around me?

It's a combination of everything below. It's society's fault, you're insecure to some degree and it is normal. I do it a lot myself. I've actually changed myself because of this. Willingly too though. The way I dress, my hair, attitude, etc.

everyone does that weather or not they realise it. they look at others and their personality or looks and say I would never do that, or I wish I could do that. or damn I wish I looked that hot or ewww they are fat!

its life we all compare what we are what we have and what we don't have. doesn't mean your a bad person. and your one of the lucky few that actually have noticed that you do it. most other people are ignorant of the fact that they compare them self's with others.

but your fine with what your doing. as long as you don't get envious of others and try to either take or destroy what others have, its all good.

Because that is how we are. We compete against girls. It isn't fun, but meh, as long as it isn't interfering with your life ce la ve!

It's how humanity is. We are constantly watching every move others make to try to improve ourselves. It's very normal. We always want what we can't have so it's the never ending road of looking at others in comparison. If it's done in an appropiate way, we can learn a lot from others. That's why this is most common when we are in our teenage years. Apart from all the insecurities that come with this period, we try to upgrade ourselves even more, to the point where we can call ourselves pretty much perfect, in our own eyes of course. But, however, if it's done in a negative way, it may affect our self esteem and lead some to depression because they can't have what they saw in another person. It's all a matter of growing up and figuring we are all unique in different ways.

It's completely normal. Especially in our childhood to teenage years, the only foundation we have for developing our psyches are our peers, family and the media.
Think about it...almost everything about you is acquired through interacting with the world and people around you. You learn from an early age that saying mean things repels others, so we learn how to appeal and draw others in by taking tips on how to be courteous and kind. Girls learn from their girlfriends how to dress and do our makeup. We learn what is appropriate for ladies our age to wear, listen to, look and act like. It's all psychological and sociological. It's quite interesting, actually. Take no shame in it. We all do it. That's life. But if you find yourself comparing, judging, or scrutinizing yourself to the point where it's affecting your life negatively, you may need to re-evaluate HOW you see yourself and others. In the end you can't be anyone but you. No matter how hard you try. And why would you?

You're competitive. You just haven't realized it... yet.

Not to be mean or anything but it could be that your insecure. You should try not looking at how someone looks but look at how they act and their personality.