4 year olds are supposed to be in diapers if they need them.
Although 4 year olds are usually potty trained and are no longer in diapers in the day it's perfectly okay and normal for 4 year olds to be in diapers even during the daytime.
Also some kids may have incontinence and may need diapers or they have a disability that requires them to be in diapers.
And in some cases a 4 year old or even older kid may need diapers at night.
It is very normal for a 3 year old to not be potty trained.
While some kids are potty trained before their 3rd birthday it's perfectly normal and fine for a 3 year old and even a 4 year old to wear diapers and not be potty trained.
Some kids will potty train around 3 years and 6 months of age and some not until age 4 and in some rare cases a child may not potty train until age 5 or close to age 5.
Most kids potty train and stop wearing diapers between the ages of 18 months to 2 years old.
However every kid is different and it's normal for even a 3 year old and 4 year old to not be potty trained.
Eventually a kid will potty train even if you don't try to potty train them yourself.
The oldest age for potty training is 5 years old.
I have a 5 year old son who is not fully potty trained but I'm sure he will be potty trained soon.
He wears diapers full time because he does not always get to the toilet so I keep my 5 year old in diapers full time until he goes to the toilet every time.
If he does not get potty trained by age 6 then I'm gonna force the issue but for now I'm letting him decide.
Most kids are potty trained before age 4 years old and some kids potty train as early as age 18 months to 2 years old.
Don't rush the kid to grow up and enjoy their diaper years because eventually they will be grown up and you'll wish you could change their diaper again.
So that is why I'm in no rush to potty train my 5 year old
He goes through 3 diapers per day and 5 packs of the Gentle Steps Size 7 diapers per month is more than enough for him and I spend $25.00 per month to diaper him and it's worth it.
He seems to enjoy his diapers and that's okay too.
The age at when most babies stop wearing diapers is between the ages of 18 months to 3 years old.
However some babies and toddlers may wear diapers still until they are 4 years old.
The age at which babies or toddlers potty train varies from child to child and there's no right age for a child to potty train.
You can try potty training your child by age 18 months but if they won't potty train then just keep them in diapers and try again when they are 2 years old or 3 years old.
Some children are not ready to potty train and stop wearing diapers until 3 years old and even 4 years old.