Use your dipstick, check it at the levels according to each temperature.
Ie. Cold & warm. The dipstick has the grooves that correspond to these temps.
My drain & fill [with the car on the hoist for an hour, pan dropped] required MORE than the manual stated. I used an extra 1.5 bottles the day i was at the shop and it was still 'low' so i had to add another 1.5 bottles the next day/ So all-in-all 3 extra bottles on top of the manual recommendation.
<2001 ES300, OEM T-IV toyota fluid>