How much urine can the human bladder hold?

Varies; 400-600mL. There is, of course, a wide range. You can say that the average male bladder capacity is around 400-600ml, or 13-20 fluid ounces. This would be the volume voided after holding urine to the point of severe urgency. If the patient is under anesthesia and the bladder distended with water, the bladder can usually hold even more, around 1000ml or 33 fl. Oz.