2 year old toddlers usually go through around 4 to 6 diapers per day and usually need their diapers changed every 2 to 3 hours during the day.
My 2 year old son has his diaper changed every 3 hours during the day but if he poops he gets his diaper changed as soon as I notice it.
You can tell whether your 2 year old needs his/her diaper changed by feeling how soggy it is.
If it's squishy between your hands then the diaper is ready to be changed.
2 year olds tend to hold their pee in and then pee in the diaper all at once during a set schedule so they don't always pee throughout the day as much as they did when they were a year old or or under a year old.
As a toddler gets older they tend to need diaper changes less often.
Check the toddlers diaper every 2 to 3 hours for wetness or you can also find diapers that have wetness indicators on them that alert you when the child's diaper is wet and needs changed.