im 16 i like to break horses,and im in the middle of remodeling my round pen , im hauling in sand and im getting me some new panels , how big do most of you have your round pens? how many feet around? thanks

I like the 50 foot best. 40 feet is just too small to lope comfortably in. In a 60 footer it seems I do a lot more running than I should have to. Course, I'm kinda old too.
Something to think about too is drainage. A freind of mine built a beautiful round pen and filled it with sand. When it rained the roundpen became a swimming pool for several days. We had to do a lot of digging to install some drainpipe.
Just something to think about.

I agree with Blondie - 50 feet seems to be a good size.

Here is a suggestion: Think about a square pen - I know, everybody uses round pens. But I picked that up from a friend long time ago. Specially if you start working with untrained horses there is a great advantage - you got a corner to run them in and stop them.

I do a lot of long lining and if a horse deciedes this is just to much fun, I can point them into a corner and stop them.

Just an idea - works fine for me.

I like the 50 or 60 diameter best. 80 is just way too big (unless you are only riding in the roundpen, then you've got some extra space) and 40 pushes into the horses "space bubble" way too much. A young untrained horse will feel too cramped in one, and feel like he/she has nowhere to go to be in a comfortable spot if you are standing in the middle. Of course the point is to get them to where You are the comfort zone, but until then, they need their space zone to learn it.
Some of my pastures are square but I don't do alot of training to stop in the corners. I have always had trouble, they can panick when pushed into a corner, or try to jump the roundpen. I train mine to stop or slow on command, so they don't need herding or forcing into a corner, rather from obedience and submission they slow or stop and come to me when I ask them.

Are you getting panels or building from wood or (?). Mine is the panels. I can move it wherever I need (though I do like the beautiful wood arenas). I leveled the area on a tractor with a Box blade, and made the sides bevel slightly off to drain the water. Yep, no fun if a round pen is a swimming pool!