URGENT ADVICE NEEDED-Putting in riding ring *now*-what size?

Hey guys...immediate advice on this would be great as I'm going to buy the wood in a little while (sometime today) for a riding ring. I need to know if there's a standard size that's appropiate for the space we have. Outdoor pen. Round or square? We have 150x50 feet available. Should we use all of it, or a regulation size? Also, what surface should it be? Thanks so much!

BTW, we can make it wider, but it would be on a hill that way. I think it's best to stay smaller but on level ground, agreed?

Personally, I would use all 150x50. You can do so much more in a bigger arena than you can in a smaller one, even if it is "regulation sized." :)

Okay, I'll do that. Or.... I can even go a lottt longer (like 250ft) if I make it narrower on the last 100ft.....so like this:

Red is the 150x50 area. Purple is the hill I could go partially up, but don't think it's a good idea. Blue is the area I could also use but if I added that to the red, the arena wouldn't be rectangular.

I wouldn't go bigger than the red for a single arena. If you want a smaller area (say a round pen) you could fit that in part of the blue area. And I agree that building a sloped area into your arena would be a bad idea. You'll want flat, uniform footing.

You might could like build it into the hill, if that makes sense. Like chop that part of the hill off but I don't know how it would look or whatever, and you might have drainage issues. But I would definitely want it to be flat.

I think I would have drainage issues if I did that....

What kind of base/footing should I have? I've heard sand is too dusty and stone dust was good, also I've heard that rubber was good (and is probably expencive....) which I've never seen. Any ideas on that? I think just grass with the natural ground is bad because of rivets in the ground when I ride in wet weather. Plus the distraction of grass to a working horse is probably not good

If you get beach sand, it packs in real well and is not as dusty as natural sand. Similar to the footing in dressage arenas

How much does it cost to cover a 150x50?