Why am I so shy around big crowds, but when I'm with one friend than I'm fine?

Have no fear, you are sooooo not alone in this. When I'm with my friends, I can be super confident and laugh a lot and be generally merry, but put in a room full of strangers, and bam. I've turned into a sad little muffin who avoids eye contact at all costs. For me, at least, I feel like it's because I trust my friends not to judge me. I know they're not going to look at me and say "Eew, you have acne," or "She is such a loser." I feel safe with them, like nothing can touch me, because I know they have my back. Lots of people, however, even people I'm acquainted with, can cause me to freak out that they're all silently judging me, or only pretending to like me. I feel like a lot of people have this issue, but try not to worry about it. Chances are, people are not trying to pick out your every flaw.

It sounds like you might have social anxiety, which is when you feel really nervous and shy around social situations when there are lots of people to interact with. Try reading this wikipedia for more information: https://en.wikipedia.org/wiki/Social_anxiety

Could be that you are, even though unknown to you, an empath. Empaths usually communicate better with one or two people because they can tune into the energy. However, get us around more than about 6 people and we will slowly get to a level of empathic overload, causing us to just shut down in an effort to keep ourselves sorted.

I'm the exact same! I have 3 really close friends, and they're the only people (apart from my family) who know what I'm really like. When I'm with them, I'm happier and I smile way more and talk sometimes too! But when I'm placed into a classroom full of people, you would find it hard to get a peep out of me unless you ask me a question (even then, it's very quiet!) I just don't like so many eyes being focused on me and judging me, and I feel so out of place because I know in my mind that nobody understands what I have to go through!

I don't know about you, but I feel like people are actually listening to what I'm saying when I'm only with one person, and when I'm with a crowd, I more often feel excluded.

Big crowds can be daunting, and you can feel like the whole world is silently judging your every move. You may find you then put a lot of pressure on yourself because of this. This is mostly why it's easier to talk with one friend, you get recognition, instant feedback from body language etc, feed off their responses and you know what they are generally thinking. You feel less pressure, and less judgment, Nonetheless, there will be times when you have to present/talk to big crowds. From my times as a presenter, I learned that things are never as bad as you think they are. It is very nerve racking, everyone gets a bit nervous - even Frank Sinatra admitted he has nerves before a show! So take a breath, a deep breath... relax, and have faith in yourself :)

I wouldn't say I'm 'shy' around big crowds, I feel my own personal social anxiety makes it stressful to not only hang out in a crowded setting, but even anticipate socializing with a group of people. It's something I'm working on through self therapy and different medications, so far nothing has helped - but I stay optimistic! Just gotta find the right method for me :)

You are probably an introvert and this is normal. Many people (introverts) are not inclined to deal with big and noisy crowds. They go for quiet places or certain people, and they even need some time alone every now and then.

big crowds can be filled with strangers, and strangers can be scary to talk to, especially when you have any type of anxiety

In a smaller group it is easier to be heard without putting in a whole lot of effort to be seen. In a group there is more pressure to get people to notice you and really hear you.