How old was Dinah when Shechem forced himself on her?

[tonychanyt]

Gen 30:

19 And Leah conceived again, and she bore Jacob a sixth son. 20 Then Leah said, “God has endowed me with a good endowment; now my husband will honor me, because I have borne him six sons.” So she called his name Zebulun. 21Afterward she bore a daughter and called her name Dinah.

Dinah was born before Joseph:

22 Then God remembered Rachel, and God listened to her and opened her womb. 23 She conceived and bore a son and said, “God has taken away my reproach.” 24 And she called his name Joseph, saying, “May the LORD add to me another son!”

Dinah was probably some months older than Joseph.

Jacob took his family, leaving Laban and Paddan-aram in Gen 31. He wrestled with God in Gen 32. He met Esau in and financially arrived at Canaan in the city of Shechem in Gen 33.

Genesis 34:

1 Now Dinah the daughter of Leah, whom she had borne to Jacob, went out to see the women of the land.

How old was Dinah?

She was old enough to have some social independence.

2 And when Shechem the son of Hamor the Hivite, the prince of the land, saw her, he seized her and lay with her and humiliated her. 3 And his soul was drawn to Dinah the daughter of Jacob. He loved the young woman and spoke tenderly to her. 4So Shechem spoke to his father Hamor, saying, “Get me this girl for my wife.”

She was old enough to get married.

Strong's Hebrew: 5291. נַעֲרָה (naarah) — 63 Occurrences

In terms of age, the word was ambiguous. Brown-Driver-Briggs:

1 girl, damsel; … especially as marriageable; … young widow

Keil and Delitzsch:

Dinah was probably between 13 and 15 at the time. … According to Genesis 37:2, Joseph was sold by his brethren when he was 17 years old, i.e., in the 11th year after Jacob's return from Mesopotamia, as he was born in the 14th year of Jacob's service with Laban.
(Note: This view is generally supported by the earlier writers, such as Demetrius, Petavius (Hengst. Diss.), etc.; only they reckon Dinah's age at 16, placing her birth in the 14th year of Jacob's service.)

How old was Dinah when Shechem forced himself on her?

I'll guess 13.