Well "normal" urine output is somewhere around mL/day - depending on intake (especially types of fluids), environmental factors, physical status (kidney function, cardiac function, infection, etc.), medications, age, etc., etc., etc. What is the average urine output for adults - What's the average amount of urine output per day? to 2 liters/day. to 2 liters/day is optimal to prevent stones. The urine hour volume test measures the amount of urine your body The normal range of urine output is to 2, milliliters per day if you have a normal.