Short answer
Your fast for that day ends, even if the period starts a minute before Maghrib, and you make up that day later. In the Hanafi school you may eat and drink, but discreetly, not in front of fasting people. If your period ends during the day, you abstain for the rest of the day and still make it up.
The start of hayd or nifas at any moment before sunset invalidates the fast; it is made up with one day and no kaffarah. She is not required to keep abstaining, but should not eat openly. If her period ends during a Ramadan day, imsak (holding back from food) for the rest of that day is wajib, and the day is still made up.
Other madhhabs
- Shafi'i
- If the period ends during the day, holding back for the rest of the day is recommended, not required.
- Maliki
- If the period ends during the day, she does not have to hold back for the rest of the day.
Explanation
A fast is valid only if you are free of menstruation for the whole day from Fajr to Maghrib. So if bleeding starts at 3 pm or at sunset minus five minutes, that day does not count. This is not your fault and there is no sin and no kaffarah. You simply make up one day after Ramadan. The four schools agree on this part.
What to do for the rest of the day:
- When it starts: you may eat and drink. The Hanafi scholars advise doing so privately, out of respect for the month and for those fasting around you.
- When it ends during the day (for example you become pure at 11 am): in the Hanafi school you must hold back from food, drink and intercourse until Maghrib, out of respect for Ramadan. That day is still made up.
- When it ends before Fajr: fast that day. See can I fast without ghusl.
- Not sure if it started before Maghrib: if you only noticed it after Maghrib and have no sign it came earlier, your fast is valid.
Some women take tablets to delay their period in Ramadan. Scholars say it is allowed if a doctor confirms it is safe, but not encouraged; the natural course is a mercy from Allah. Fasts must be made up before the next Ramadan if possible. See Ramadan fasting rules and what breaks your fast.
The evidence
Quran, Surah Al-Baqara 2:185
شَهْرُ رَمَضَانَ ٱلَّذِىٓ أُنزِلَ فِيهِ ٱلْقُرْءَانُ هُدًۭى لِّلنَّاسِ وَبَيِّنَٰتٍۢ مِّنَ ٱلْهُدَىٰ وَٱلْفُرْقَانِ ۚ فَمَن شَهِدَ مِنكُمُ ٱلشَّهْرَ فَلْيَصُمْهُ ۖ وَمَن كَانَ مَرِيضًا أَوْ عَلَىٰ سَفَرٍۢ فَعِدَّةٌۭ مِّنْ أَيَّامٍ أُخَرَ ۗ يُرِيدُ ٱللَّهُ بِكُمُ ٱلْيُسْرَ وَلَا يُرِيدُ بِكُمُ ٱلْعُسْرَ وَلِتُكْمِلُوا۟ ٱلْعِدَّةَ وَلِتُكَبِّرُوا۟ ٱللَّهَ عَلَىٰ مَا هَدَىٰكُمْ وَلَعَلَّكُمْ تَشْكُرُونَ ﴿١٨٥﴾
The month of Ramadhan [is that] in which was revealed the Qur'an, a guidance for the people and clear proofs of guidance and criterion. So whoever sights [the new moon of] the month, let him fast it; and whoever is ill or on a journey - then an equal number of other days. Allah intends for you ease and does not intend for you hardship and [wants] for you to complete the period and to glorify Allah for that [to] which He has guided you; and perhaps you will be grateful.
Fasts left for a valid reason are made up on other days.
Sahih al-Bukhari 304
Sahih... أليس إذا حاضت لم تصل ولم تصم ...
"Is it not so that when she menstruates she neither prays nor fasts?"
A menstruating woman does not fast.
Sahih Muslim 335
Sahih... فنؤمر بقضاء الصوم ولا نؤمر بقضاء الصلاة ...
"We were commanded to make up the fast and were not commanded to make up the prayer."
Missed fasts are made up.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Sawm, chapter on what breaks the fast and what does not. A woman whose period ends during the day holds back for the rest of it; one whose period starts eats discreetly.
- al-Fatawa al-Hindiyya, Kitab al-Sawm, chapter on the excuses that permit not fasting. The fast is broken by the arrival of hayd at any time of the day.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.