I'm 13 years and 8 months

Most adults tell their age in years, not years and months.

EnglishmavenMost adults tell their age in years, not years and months.

Ok, but suppose the situations in which the exact age is needed to be said. I mean how do you say someone's age then?
for example ...
A: How old is your liitle daughter?
B: ----------------------------------------------------------------------------.
?

It's unusual (but not incorrect) to include months when giving our age. Parents will use months for babies, maybe up to about 2 years old.

So usually the reply would be "I'm 13" or "I'm almost 14" or "I'll be 14 in October."

Once you include the word "years" you use "old."
I'm 13 years old.
I'm 13 years and 8 months old.

Edit: Sorry - I got interrupted and ended

BarbaraPAIt's unusual (but not incorrect) to include months when giving our age. Parents will use months for babies, maybe up to about 2 years old.So usually the reply would be "I'm 13" or "I'm almost 14" or "I'll be 14 in October."Once you include the word "years" you use "old."I'm 13 years old.I'm 13 years and 8 months old. Edi

up to 2 years old = from zero (birth) to two years (24 months), (up means increasing or going up)
about = approximately,
maybe = I guess.