How many panels to buy for round pen

I am going to by round panels soon .So my question is how many panels should I buy?I think 12 all I going to use it for is breaking and riding in .

Depends on what length the panels are going to be but I personally don't like working in anything less then a 50' pen.

Usually, I see 11 10 foot panels and a gate.

I was just researching this earlier today on google. What I found was: Decide the diameter of your pen--50ft, 60ft whatever. Multiply by 3.14 for the circumference and divide by the length of your panels. Then you have the option of rounding up or down. Hope that helps.

I like about 60ft at least. I looked into buying panels, kind of expensive. I might end up making my own.