The ideal size is just big enough for your dog to stand up, turn around, and lie down comfortably, and just long enough so that his nose and rear end don't touch each end of the crate.
This dog cage is great for you. It lacks bolts and nuts making assembly easier than ever. No tools are needed, slide the pieces together. This pet crate also provides lots of ventilation improvement. High-quality durable powder coating on Iron to protect from rain and sunlight.