Iddah Calculator
Calculate the waiting period (iddah) duration for divorced or widowed Muslim women. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculateFormula
The iddah duration depends on the reason for marriage dissolution (divorce, death, khula), whether the woman menstruates, and whether she is pregnant. Pregnant women wait until delivery. Divorced menstruating women wait 3 cycles. Widows wait 4 months and 10 days.
Last reviewed: December 2025
Worked Examples
Example 1: Iddah After Divorce for Menstruating Woman
Example 2: Iddah for a Widow
Background & Theory
The Iddah Calculator applies the following established principles and formulas. Islamic financial and religious calculations operate within a framework that integrates theological principles with precise mathematical methodology. Zakat, one of the five pillars of Islam, requires payment of 2.5% of qualifying wealth held above the nisab threshold for a complete lunar year. The nisab is pegged to the value of 85 grams of gold or 595 grams of silver, whichever provides the lower threshold, and must be recalculated against current market prices. Qualifying wealth includes cash, savings, business inventory, and investment assets, but excludes primary residence, personal-use items, and tools of trade. Hijri calendar conversion is essential for determining Ramadan dates, Zakat anniversaries, and contract terms expressed in lunar months. The Hijri calendar contains 12 lunar months totalling approximately 354.37 days, making it roughly 11 days shorter than the Gregorian year. Converting between calendars requires accounting for the accumulated drift: since the Hijri epoch of 622 CE (the Prophet's migration from Mecca to Medina), the difference compounds annually. Qibla direction calculation employs spherical trigonometry to determine the great-circle bearing from any point on Earth toward the Kaaba in Mecca (coordinates 21.4225°N, 39.8262°E). The formula accounts for the curvature of the Earth, meaning the bearing from New York to Mecca is approximately northeast rather than the intuitive eastward direction seen on flat maps. Prayer times are determined by solar angles: Fajr begins when the sun is 15-18 degrees below the horizon before dawn; Dhuhr at solar noon; Asr when shadow length equals object height plus its shadow at noon; Maghrib at sunset; and Isha when twilight disappears. These calculations vary by latitude and season, requiring location-specific algorithms. Islamic finance prohibits riba (interest), requiring profit-sharing structures such as Mudarabah (capital provider and entrepreneur share profits at a pre-agreed ratio) and Musharakah (joint venture with proportional profit and loss sharing).
History
The history behind the Iddah Calculator traces back through the following developments. Islamic civilisation made foundational contributions to mathematics and astronomy that underpin many of the calculation methods still used today. Muhammad ibn Musa al-Khwarizmi, working at the House of Wisdom in Baghdad in the 9th century, authored Al-Kitab al-mukhtasar fi hisab al-jabr wal-muqabala, the work from whose title the word algebra derives. His systematic approach to equation solving provided tools directly applicable to financial and calendar calculations. Al-Biruni in the 11th century developed sophisticated methods for calculating geographic coordinates and direction, including early formulations of what became the qibla calculation. The Hijri calendar was formally established by Caliph Umar ibn al-Khattab in 638 CE, fixing the Prophet Muhammad's migration (Hijra) from Mecca to Medina in 622 CE as the epoch. This calendar standardised religious observances across the expanding Muslim world. Islamic inheritance law (Faraid) was codified from Quranic verses and Hadith during the early Islamic period, establishing precise fractional shares for defined classes of heirs. The complexity of multi-heir scenarios drove development of sophisticated fraction arithmetic among early Islamic jurists and mathematicians. The Ottoman Empire administered Zakat as a state function for centuries, integrating it with broader fiscal policy until the empire's dissolution after World War I. The 20th century saw Islamic finance principles largely dormant in formal banking until the resurgence of Islamic banking in Egypt (Mit Ghamr Savings Bank, 1963) and the Gulf states following the 1973 oil boom provided capital for institution-building. The Accounting and Auditing Organization for Islamic Financial Institutions (AAOIFI), established in Bahrain in 1991, and the Islamic Financial Services Board (IFSB), established in Kuala Lumpur in 2002, created the standards infrastructure for modern Islamic finance. The global Islamic finance industry has grown to approximately three trillion US dollars in assets, spanning banking, takaful insurance, sukuk bonds, and Islamic funds across over 80 countries.
Frequently Asked Questions
Formula
Iddah = f(reason, menstruation, pregnancy)
The iddah duration depends on the reason for marriage dissolution (divorce, death, khula), whether the woman menstruates, and whether she is pregnant. Pregnant women wait until delivery. Divorced menstruating women wait 3 cycles. Widows wait 4 months and 10 days.
Worked Examples
Example 1: Iddah After Divorce for Menstruating Woman
Problem: A woman is divorced on March 21, 2026. She has regular menstrual cycles. Calculate her iddah period.
Solution: Type: Divorce with menstruation\nIddah duration: 3 complete menstrual cycles\nApproximate duration: 3 x 30 days = 90 days\nStart date: March 21, 2026\nEnd date: March 21 + 90 = June 19, 2026\nNote: Actual end depends on completion of 3 full cycles, not calendar days.
Result: Iddah ends approximately June 19, 2026 (90 days from divorce date)
Example 2: Iddah for a Widow
Problem: A woman's husband passes away on January 15, 2026. She is not pregnant. Calculate her iddah period.
Solution: Type: Death of husband, not pregnant\nIddah duration: 4 months and 10 days = 130 days\nStart date: January 15, 2026\nEnd date: January 15 + 130 = May 25, 2026\nDuring this time she observes hidad (mourning)\nShe should remain primarily in the marital home
Result: Iddah ends approximately May 25, 2026 (130 days from date of death)
Frequently Asked Questions
What is iddah and why is it prescribed in Islam?
Iddah (also spelled iddat or iddat) is the mandatory waiting period that a Muslim woman must observe after the dissolution of her marriage through divorce or the death of her husband. The primary purposes of iddah include establishing whether the woman is pregnant to clarify lineage and parentage, providing a cooling-off period during which reconciliation may occur in the case of revocable divorce, showing respect for the marital bond and the deceased husband, and protecting the rights of both parties. Iddah is established through multiple verses in the Quran, including Surah Al-Baqarah (2:228, 2:234) and Surah At-Talaq (65:4). During iddah, the woman generally remains in her marital home and observes certain restrictions.
What are the different types and durations of iddah?
The duration of iddah varies based on the circumstances. For a divorced woman who menstruates, the iddah is three complete menstrual cycles (three quru), typically around 90 days. For a divorced woman who does not menstruate (post-menopausal), the iddah is three lunar months, approximately 89 days. For a widow who is not pregnant, the iddah is four months and ten days (approximately 130 days). For a pregnant woman, regardless of divorce or widowhood, the iddah extends until delivery of the child. For khula (wife-initiated dissolution), scholars differ between one menstrual cycle and three cycles. The iddah begins from the date of divorce pronouncement or the husband's death.
What are the rules and restrictions during the iddah period?
During iddah, Islamic jurisprudence prescribes several guidelines. In revocable divorce (talaq raj'i), the woman should remain in the marital home, and the husband has the right to take her back. She should not leave the house unnecessarily, though scholars permit leaving for genuine needs like medical appointments, work, or essential errands. A widow observing iddah should avoid adornment, perfume, and wearing bright or festive clothing. She should not accept marriage proposals, though indirect expressions of interest to a widow are permissible. After iddah ends, the woman is free to remarry. These rules may vary between different schools of Islamic jurisprudence (Hanafi, Maliki, Shafi'i, Hanbali).
How does pregnancy affect the iddah period in Islamic law?
Pregnancy has a unique effect on the iddah calculation. Regardless of whether the marriage ended through divorce or the death of the husband, if the woman is pregnant, her iddah continues until she gives birth. This ruling is based on Quran 65:4 which states 'And for those who are pregnant, their term is until they give birth.' This means the iddah could be shorter or longer than the standard period. If a woman gives birth one day after divorce, her iddah is effectively one day. If she is in early pregnancy at the time of divorce, her iddah could extend to nine months. After delivery, she is immediately free to remarry if she chooses, though scholars recommend a brief recovery period.
What is the difference between iddah for divorce and iddah for the death of a husband?
The key differences between iddah for divorce and widowhood are significant. For divorce, the iddah is three menstrual cycles (or three lunar months for non-menstruating women), while for widowhood it is four months and ten days. During divorce iddah, the husband is financially responsible for the wife's maintenance including housing, food, and clothing. During widow's iddah, the maintenance obligation falls on the deceased's estate or her own resources. In revocable divorce, the husband can take his wife back during iddah, but this is obviously not possible in widowhood. The mourning obligations differ as well. A widow must observe hidad (mourning), which includes avoiding adornment and staying primarily at home, while a divorced woman has fewer mourning restrictions.
How accurate are the results from Iddah Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy