How Mizaanly Calculates Islamic Inheritance
This page sets out how the Mizaanly calculation engine works: which rules it applies, which position it takes where the madhabs differ, how results are checked, and what the calculator does not currently do. It is written so that a scholar, a solicitor or a careful user can see the basis of a result rather than having to take it on trust.
For the underlying references, see our sources page. For how content is reviewed and corrected, see our editorial policy.
Our approach
Mizaanly is designed to help users understand and calculate Islamic inheritance according to established Faraid principles, while recognising that inheritance involves genuine differences between the Sunni schools of Islamic jurisprudence.
The engine is built around the four Sunni madhabs — Hanafi, Shafi’i, Maliki and Hanbali. Where a recognised difference exists between them, Mizaanly applies the position of the school the user has selected rather than presenting one view as universally applicable.
Mizaanly follows the classical/formal position of each madhab. Where later or modern application within a school reaches a different result, the calculator stays with the classical methodology, and says so. Applying one consistent standard across all four schools matters more than following whichever position is most common in contemporary practice.
The aim is to make the calculation transparent, structured and understandable, while directing users to appropriate professional or scholarly support for matters that require individual judgement.
What the calculation covers
The engine models the main categories and rules required for a Faraid distribution:
- Dhul-Furud — heirs with a prescribed Qur'anic share
- Asabah — residuary heirs, taken in order of priority
- Hajb — exclusion, where a nearer heir blocks a more distant one entirely or reduces their share
- Awl — proportional adjustment where the prescribed shares exceed the estate
- Radd — treatment of a surplus where the prescribed shares fall short and no Asabah is present
- Spouse-related rules, including the treatment of a surviving spouse where a surplus arises
- Madhab-specific differences, applied according to the school selected
- Special classical cases recognised by the engine, such as al-‘Umariyyatan, al-musharrakah and grandfather-with-siblings scenarios
The prior claims on an estate — funeral expenses, debts and a wasiyyah of up to one third — are deducted before any Faraid distribution is calculated.
Heirs the calculator supports
The engine holds definitions for 18 heir types. 14 of these are currently selectable in the calculator interface, across five groups:
- Spouse — husband or wife
- Children — son, daughter
- Parents — father, mother
- Grandparents — grandfather, grandmother
- Siblings — full brother, full sister, paternal half-brother, paternal half-sister, maternal half-brother, maternal half-sister
Four heir definitions exist within the underlying rules but are not currently selectable through the interface: the son’s son and son’s daughter, and the full and half paternal uncle. An estate involving those relatives needs case-specific scholarly analysis rather than this calculator.
Users should check the limitations below before relying on a result for a complex family structure.
Dhawu al-Arham
Dhawu al-Arham are outside the current calculator’s scope. They are not a supported category and cannot be selected.
The term refers to relatives connected to the deceased through a female link who are neither Dhul-Furud nor Asabah — a daughter’s son, a maternal uncle, a sister’s children. Classically they inherit only where no Dhul-Furud and no Asabah heir survives, and the schools differ on how they are then ranked among themselves.
This is explained here for understanding, not as a description of what the calculator does. An estate that turns on Dhawu al-Arham requires a qualified scholar. The concept is covered further in what Faraid is.
One point of vocabulary, because it causes confusion: maternal half-siblings are sometimes called “uterine” relatives. They are not Dhawu al-Arham. They hold a prescribed share under An-Nisa 4:12 and are fully supported by the calculator.
The four madhabs
Mizaanly supports calculation according to the Hanafi, Shafi’i, Maliki and Hanbali schools. Each is implemented as its own rule set within the engine, covering that school’s treatment of Radd, the grandfather alongside siblings, and the special cases it recognises.
For most family compositions all four produce the same distribution. Where they diverge, the school selected determines the result. The differences, worked through the same family, are set out in our guide to how the four madhabs differ on Faraid.
The Radd position Mizaanly applies
Radd arises where the prescribed shares do not exhaust the estate and no Asabah heir is present to take the balance. Because the schools differ here, and because the difference affects real money, the position Mizaanly applies is stated explicitly.
On the classical position of all four madhabs, the surviving spouse receives only their fixed Qur'anic share and does not share in the surplus. The schools differ in what happens to that surplus:
| Madhab | Spouse shares in the surplus? | Treatment of the surplus |
|---|---|---|
| Hanafi | No | Radd — returned proportionally to the remaining Dhul-Furud heirs |
| Shafi’i | No | No Radd mechanism; classical bayt al-mal treatment |
| Maliki (classical) | No | Classical bayt al-mal treatment |
| Hanbali | No | Radd — returned proportionally to the remaining Dhul-Furud heirs |
The reasoning approved for Mizaanly is that classical jurists treat Radd as a corrective distribution among the relevant blood-related sharers, while the spouse retains their fixed Qur'anic share and is treated differently from those sharers.
Where later practice differs. Some later Maliki application in jurisdictions without a functioning bayt al-mal reaches a different result. Mizaanly follows the classical position stated above, consistently across all four schools.
How this works in the UK. There is no bayt al-mal in the United Kingdom. Where a school directs the surplus there, the engine returns it to the remaining blood relatives who hold a prescribed share, and labels the result as such rather than applying it silently. The spouse remains limited to their fixed Qur'anic share. Where a surviving spouse is the only Dhul-Furud heir, there is no one else to receive the surplus and the spouse takes the estate.
This position was confirmed by the Mizaanly scholarly reviewers in September 2026 and is implemented in engine version 7.4.0. The supporting references are listed on our sources page.
Disputed rules
Islamic inheritance contains areas where the Sunni schools differ in their reasoning and conclusions. Mizaanly does not hide those differences. The engine holds 12 documented disputed rules, each recording the position of the relevant schools together with its source references, and applies the rule associated with the selected madhab.
Areas where differences arise include:
- The grandfather alongside full or paternal siblings
- Treatment of a surplus, and the position of the spouse within it
- Al-musharrakah (al-Ḥimariyyah)
- Al-‘Umariyyatan — the mother’s share alongside a spouse and the father
- Multiple grandmothers sharing the one sixth
- Kalalah and whether the grandfather blocks siblings
Where a calculation triggers one of these rules, the result explains which position has been applied and notes that another school would reach a different answer.
Qur'an and hadith evidence
The prescribed shares rest on three passages of Surah An-Nisa, each held in the engine with its Arabic text, translation and reference:
- An-Nisa 4:11 — the shares of children and parents
- An-Nisa 4:12 — the shares of spouses and maternal half-siblings
- An-Nisa 4:176 — full and paternal siblings in the kalalah case
Alongside these the engine holds three hadith narrations supporting particular rules, including the grandmother’s one sixth and the son’s daughter’s share. The full list, with the collections they come from, is on our sources page.
Calculation sequence
At a high level the engine works in this order. Nothing later runs until the earlier steps are complete.
- Take the estate figures and the surviving heirs entered by the user.
- Deduct funeral expenses, debts and any wasiyyah, capped at one third. A bequest to an heir does not take effect without the other heirs’ consent after the testator’s death.
- Determine which heirs are eligible under the rules of the selected madhab.
- Apply Hajb, recording which heir has been excluded and by whom.
- Identify the Dhul-Furud heirs and assign their prescribed shares.
- Apply Awl where the prescribed shares exceed the estate.
- Distribute the residue to the Asabah where one is present.
- Where no Asabah is present and a surplus remains, apply the selected school’s treatment of that surplus.
- Apply the selected madhab’s position on any disputed rule the case triggers.
- Produce the distribution with its supporting explanation and references.
The exact result depends on the family structure and on the rules applicable to the selected madhab.
Validation and testing
The calculation system includes several independent layers intended to reduce errors and surface inconsistent inputs or rule interactions:
- Input validation — checks the heirs and figures entered before any calculation runs
- Fiqh rule validation — checks the rules applied against the heir definitions and madhab rule sets
- Calculation hardening — a post-processing layer that re-checks the produced distribution
- Governance checks — further checks on the result before it is shown
The engine is also covered by an automated test suite run against known Faraid outcomes, currently 566 assertions spanning family structures and madhab-specific results, including cases for Awl, Radd, Hajb, the grandfather scenarios and the special classical cases. A separate suite checks that every heir definition carries a correct display label, so that no heir can be shown under a wrong or generic name.
Automated tests confirm that the engine behaves as configured. They do not by themselves establish that a fiqh position is correct; that is the role of scholarly review.
Scholarly review
Mizaanly’s Islamic inheritance methodology is associated with:
- Mufti Maruf Al Hasan — MA Fiqh, Markazul Quran
- Mufti Azizur Rahman — MA Fiqh & Islamic Economics
The scholarly team selects and reviews the Islamic subject matter covered by Mizaanly, and reviews relevant material and calculation results. Where content or references require verification, they are checked as part of the review process before publication.
Scholarly review is ongoing rather than a one-off sign-off. The team continues to examine calculation results and identify possible edge cases or implementation issues so the system can be improved over time. The Radd position described above is an example: it was raised as a question, ruled on, and the engine and the affected pages were then changed to match.
Limitations
Mizaanly is a calculation and educational tool. It is not a replacement for a qualified Mufti, a solicitor, or another appropriate professional adviser where an estate requires individual legal or scholarly judgement.
- A result depends on the information entered and on the cases the system currently supports.
- Four heir definitions are not selectable, and Dhawu al-Arham are outside scope entirely.
- The four supported schools are Sunni. Ja‘fari inheritance is not implemented.
- Complex or contested situations — a missing heir, an unborn child, simultaneous deaths, disputed paternity, an heir who is not Muslim — may require case-specific scholarly analysis, legal advice, or both.
- The calculator does not value an estate and does not calculate Inheritance Tax.
- For UK estates, Islamic inheritance rules and UK law are separate bodies of rules. A Faraid calculation does not itself determine the legal administration of an estate.
What the calculator covers and does not cover is set out alongside the tool itself on the calculator page.
Keeping this under review
The methodology and calculation system are subject to ongoing review rather than a fixed schedule. Material issues, unusual results, suspected calculation errors, changes to the rules implemented by the engine and other significant concerns may each trigger further review and testing.
The aim is not to publish a calculator and leave it unchanged. The system is examined on a continuing basis so that problems can be identified and corrected as they arise. Our editorial policy sets out how that works in practice.
Report a possible error
We welcome corrections and constructive feedback. If you believe a calculation, explanation, source reference or any other part of Mizaanly may be incorrect, please contact us.
Please include as much detail as possible, including the relevant page, calculation or rule. We appreciate users bringing potential issues to our attention, and will investigate and correct confirmed errors as soon as reasonably possible.
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