Text index limit

I’m guessing I can suggest stuff here so. I am surprised there is no option for this where you can choose how many characters can only show up on the index of your blog. Because I would like to limit the characters. It over extends my index and causes the theme to mess up a bit. So I would like to see a plugin or this added as a default option to wordpress. So we can limit how many characters are shown in posts on the index of our blogs.