Bearded questions?

What is the correct enclosure size for an bearded dragon? what about a pair?

i have have found all kinds of sites with info....i have gotten these similar sizes for most of them......do they sound ok?....36''x18''x18''...and 48''x12.5''x20''

for a single 36-18-18 is good but for a pair 48-18-18 will work, bigger is always better with BDs