how big for a brew pot if going all grain, 5 gallon batches....

how big for a brew pot if going all grain, 5 gallon batches. I understand my mash tun should be bigger to accomodate all the grains, but will a 6 gallon brew pot work for boiling? or do i need bigger

You need bigger. I have a 50 litre keg which is only just big enough for 25 litre batches without the boil frothing over (which it can do regardless of boil intensity). So I would recommend you go minimum 10 gallons

You will be boiling 6.5 gal of wort for 5 gal of beer.And I see OZ says 10 gal after I started typing and thats what I was goiing to say and for same reason. Even bigger is better if your going all-grain start thinking double batches now and get or make the bigger pot.