Key points
- The minimum purity (tuhr) between two periods is 15 days. There is no maximum.
- A clean gap of less than 15 days between two bleedings does not count as purity; it is treated as continuous bleeding.
- Blood that starts before 15 days of purity have passed cannot begin a new haiz.
The rule
In the Hanafi school the shortest valid purity between two periods is 15 days. This number is the companion of the 10-day maximum for haiz: together they keep a healthy cycle distinct from irregular bleeding.
Short clean gaps are not purity
Bleeding is not always continuous. Many women see blood, then a day or two of nothing, then blood again. In the relied-upon Hanafi position (following Imam Abu Yusuf), a clean gap shorter than 15 days that falls between two bleedings is treated as if blood had flowed throughout. It is called an invalid purity (tuhr fasid).
Example: 3 days of blood, 4 clean days, 2 days of blood. The whole 9 days count as one bleeding, so all of it is haiz. You should still pray on the clean days because you cannot know the outcome yet; once it is clear, the prayers prayed in those days were not owed, and any obligatory fast kept then is made up.
When blood comes back too early
If blood starts before 15 days of purity have passed since your last haiz, that blood cannot be the start of a new period. It is istihaza until 15 days of purity are complete. If it continues after that, the rest is judged by the normal haiz rules.
Istihaza days count towards purity
Days of istihaza count as purity for this rule. If a long bleeding ends with some days of istihaza and then you are clean for 15 days, the istihaza days and the clean days together make up the purity before the next haiz.
Using the calculator
If you do not yet have a fixed habit, the Taharat & Dam Calculator lets you enter your days of blood and clean days in order. It joins short gaps, applies the 3, 10 and 15-day limits, and shows each day on a timeline.
This guide is educational and follows mainstream Hanafi positions. For your own situation, please consult a qualified scholar. See the disclaimer, the glossary and how rulings are worked out.