What is the minimum or obligatory urine output in a day for healthy kidneys?

The minimum urine output necessary / day = the amount of urine required to excrete "the solute load" consumed each day.

In an average individual the minimum Solute load excreted daily by kidney is 600-800 mOsm/day. As we know in healthy person, the Maximum urine-concentrating capacity of kidneys is 1200 mOsm/L.

We can calculate the Obligatory urine output in healthy individuals.

for 1200 mOsm solute excretion, the min. amount of urine output required is 1 Liter.

for 600 mOsm solute excretion, the min. amount of urine output will be 0.5 Liter.

Therefore, we require a minimum 500ml of obligatory urine output to excrete daily solute load from our body.