How old was Ishmael when Abraham sent him away?

[TonyChanYT]

Genesis 16:

15 "And Hagar bare Abram a son: and Abram called his son’s name, which Hagar bare, Ishmael.” Abram was 86 years old.

Genesis 21:

5 Abraham was a hundred years old when his son Isaac was born to him.

Ishmael was about 14 (100 − 86) years old at this point.

8 And the child grew and was weaned. And Abraham made a great feast on the day that Isaac was weaned.

In accordance with rabbinical traditions:

weaning can take place during a relatively long period, from 18 months up to five years of age.

Now, Ishmael was between 15 and 19 years old.

9 But Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, laughing. 10 So she said to Abraham, “Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac.” 11 And the thing was very displeasing to Abraham on account of his son. 12 But God said to Abraham, “Be not displeased because of the boy [H5288] and because of your slave woman.

Strong's Hebrew: 5288. נַ֫עַר (naar) — 240 Occurrences

Strong's Exhaustive Concordance
babe, boy, child, damsel, lad, servant, young man
From na'ar; (concretely) a boy (as active), from the age of infancy to adolescence;

Whatever Sarah says to you, do as she tells you, for through Isaac shall your offspring be named. 13 And I will make a nation of the son of the slave woman also, because he is your offspring.”

There does not seem to be much time elapsed between the above and the next event:

14 So Abraham rose early in the morning and took bread and a skin of water and gave it to Hagar, putting it on her shoulder, along with the child [H3206], and sent her away. And she departed and wandered in the wilderness of Beersheba.

Strong's Hebrew: 3206. יָ֫לֶד (yeled) — 89 Occurrences

Strong's Exhaustive Concordance
boy, child, fruit, son, young man

How old was Ishmael when Abraham sent him away?

He was 16.