There is no exact limit to what extent a woman can shorten her hair. A woman can shorten her hair provided that she takes into consideration the following two points:
1. She avoids a hairstyle that is peculiar to males.
2. She takes the husband’s permission in case she is married.
3. She must cover her head and not to expose it except to her husband or her mahram (non-marriageable relative).
Elaborating on the ruling of shortening their hair, we’d like to quote the following fatwa issued by Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
“A woman can shorten her hair provided she avoids a hairstyle peculiar to men. The Prophet (peace and blessings be on him) has cursed men who copy women and women who copy men. This applies to hairstyle and appearance. So long as she avoids this, she is permitted to cut her hair. There is no prohibition in the sources. We should remember that originally the rule is permission; prohibition is only an exception.
however, we must add a word of caution. A Muslim woman is required to cover her head and not expose it except to her husband or her mahram (non-marriageable relative).
Shedding more light on this issue, we’d cite the following Fatwa:
Islamic Law differentiates between ‘shaving’ and ‘shortening’ one’s hair. Shaving hair (i.e., cutting it by a sharp object such as a razor blade or skin-close clippers, etc.) is forbidden for women unless there is a justifiable reason such as when the woman needs an operation on her head or has to undergo special treatment on her scalp. But shortening her hair is allowed if she desires to do so. The only thing is that when women shorten their hair, they should not be doing this to imitate men. Therefore, the intention is important behind the act.