Maximum height of a post

I would like all new post to have the same height.

By this i mean if a long post have like 500 words, i want it to show up in a summary at the homepage.

I know there is the more tag and the excerpt but thats not what i mean.

I just want a fixed size for every post, with a read more tag behind it, so that my layout has more symmatry.

Is there a way to do this, or maybe a plugin?

I’ve seen plugins like post-teaser and everymore, and they only show the first paragraph automaticly, but if one paragraph is short, and the next is long, the posts still have different heights.

please help me