When a baby is hydrated enough they should be soaking the diaper or at least getting the diaper nearly soaked.
The diaper should be pretty full and squishy when you change their diaper unless you change the diaper before it gets too full.
A newborn might have 8 to 10 wet diapers per day while an older baby such as 1 year and above may only have 5 to 6 wet diapers per day.
If the diaper is barely wet after a few hours then the baby or toddler may be dehydrated and need more fluids.
But if the diaper is at least partially wet or soaked then the baby or toddler is hydrated enough.
Diapers are really absorbent today and can hold around 3 or 4 wetting from the toddler or baby and they hold the wetness away from the babies skin.
Babies older than 6 weeks of age usually wet at least 4 to 6 diapers per day and they are usually pretty wet and may weight 1/2 lb or even a lb depending on the diaper and the amount of urine.
I never weighed a wet diaper before to see the exact weight but when my babies were in diapers they had soaking wet diapers whenever I changed them.
I changed them every 2 to 3 hours and they wet quite a bit which meant they were getting hydrated enough.