Why do my iPhone pictures take up so much gigabytes?

I have a 32GB iPhone 5, and I'm trying to free up space on my phone, I only have 379 pictures (31 videos but they aren't long, longest video is 5 minutes) and it's used up 6.4 GB! My friends have somewhere near 800 pictures and they only use up around 1 or 2 GB. Any reason why my pictures use up so much GB? And any way I can make them use less?

The videos…

Well, go into "General --> Usage" and see. I just checked mine and found 2 vids using up 2GB+ total (one was 8 mins, the other 13 mins). I'll bet the total usage of those 31 vids is eating up the majority of that 6.4gb.

You can change the setting. The picture use much GB, as it is clear and big in size.

It's about those videos which eat up your memory on the device. Even if they are not so long and lengthy ones still they would be occupying more space. Try deleting them, it would free up the space for sure.

The games for exemple

You should check the videos in particular. The iPhone 5 records in 1080p HD. So videos even if you feel they are short actually are quite big in size.

As far as the pictures the photos are on average 2.5MB per pic, so again look into that & see where you could shave off some space.

Try using some online storage options. Flickr, Google+, Facebook, Dropbox, Box, etc there are many of them that do that, but the 1st 3 in particular concern media (pics/vids). Also you could use an app for the computer called PhoneClean that would help further regain some space. Free.