Mahrul Mithl in Islam

1. Family mahr or mahrul mithl is determined in the following way: look at any woman in the girl's father's family who is similar or equal to this girl. That is, if the girl is young, the woman must also be young at the time of marriage. If the woman is beautiful, this girl must also be beautiful. If the woman's marriage had taken place when she was a virgin, this girl's marriage must also take place while she is a virgin. The wealth that this girl possesses at the time of her nikah, that woman also had possessed the same at the time of her nikah. The place or locality from which this girl is, that woman must also be from the same place. If this girl is religious-minded, intelligent, well-mannered and educated, that woman must also be the same. In short, this girl whose nikah is being performed now, must also possess the qualities that that woman possessed at the time of her nikah,. If they share the same qualities, then the mahr that was stipulated for that woman will be the mahrul mithl for this girl.

2. Women of the girl's father's family refer to the girl's sisters, paternal aunts, cousins (children of paternal uncles), etc. In other words, girls or women who are connected to her paternal grandmother. When determining the mahrul mithl, the mahr of the mother is not considered. However, if her mother is also of the same family as that of her father's, e.g. if her father marries his cousin (paternal uncle's daughter), then the mother's mahr will also be regarded as mahrul mithl.

Reference: Nikah (Marriage) In Islam Written By Maulana Ashraf Ali Thanvi Rahmatullah Alaihi