The rules of inheritance

This is the reference behind the calculator — the principles it applies, in plain language. You can read the same material in the app at qurangallery.com/mirath/rules.

Order of distribution

Before any heir inherits, four claims are met from the estate. Classical fiqh lists them in this order:

1. Funeral expenses — a dignified burial.
2. Debts — everything owed to people and to God.
3. Bequest (waṣiyya) — up to one third of what remains, to non-heirs.
4. The fixed shares (farāʾiḍ) — the rest is divided among the heirs by the rules below.

The calculator treats funeral expenses and debts as a combined first deduction — both are settled before anything else — then caps the bequest at one third of what remains. Its “Debts, funeral & bequest” section nets the estate down to the amount that is actually divided.

The fixed shares (al-furūḍ)

Allah names the shares of close relatives in the Qurʾan — chiefly verses 4:11, 4:12, and 4:176. Each fraction is conditional on who else survives. There are six of them.

Fraction	Who can receive it
½	Husband (with no child) · a sole daughter · a sole son’s daughter · a sole full sister · a sole paternal sister
¼	Husband (with a child) · wife or wives, shared (with no child)
⅛	Wife or wives, shared (with a child)
⅔	Two or more daughters · two or more son’s daughters · two or more full sisters · two or more paternal sisters
⅓	Mother (no child and fewer than two siblings) · two or more maternal siblings, shared equally
⅙	Father (with a child) · mother (with a child or two or more siblings) · grandfather (with a child) · grandmother · a sole maternal sibling · a son’s daughter completing a daughter’s ⅔ · a paternal sister completing a full sister’s ⅔

Residuary heirs (al-ʿaṣaba)

After the fixed shares are paid, whatever remains goes to the residuary heirs (ʿaṣaba) — the agnatic relatives, nearest first: the son, then the son’s son, the father, the grandfather, then the brothers and their lines.

Where a male and female of the same rank inherit together — a son and a daughter, a brother and a sister — the male takes the share of two females (a two-to-one split). A daughter or a sister normally takes a fixed share, but becomes a residuary when she inherits alongside her brother, or — for a full or paternal sister — alongside a daughter.

Blocking (al-ḥajb)

A nearer heir can exclude a more distant one, either completely (ḥajb ḥirmān) or by reducing their share (ḥajb nuqṣān). For example: a son blocks the son’s son and all the siblings; the father blocks the brothers; the mother is reduced from ⅓ to ⅙ when a child, or two or more siblings, survive.

The calculator shows blocked heirs greyed out with the reason they were excluded, so nothing is hidden.

ʿAwl and radd

ʿAwl (over-subscription): sometimes the fixed shares add up to more than the whole estate — for example a husband (½) with two full sisters (⅔). The base of the problem is raised so the shares fit, and everyone is reduced in proportion.

Radd (return of surplus): the opposite — the fixed shares fall short and there is no residuary heir to take the remainder. The surplus is returned to the fixed-share heirs in proportion, with one exception: the spouse never shares in the radd.

The four schools (al-madhāhib)

For the overwhelming majority of families, the four Sunni schools — Ḥanafī, Mālikī, Shāfiʿī, and Ḥanbalī — give exactly the same result. The fixed shares, blocking, ʿawl, and radd are common ground. They diverge mainly in one situation: when a grandfather inherits alongside full or paternal siblings, with no father in between (the classical books call this al-Jadd wa al-Ikhwa).

School	The grandfather alongside siblings
Ḥanafī	Treats the grandfather as a father, so he excludes the siblings entirely.
Mālikī	The grandfather shares with the siblings (muqāsama); also applies al-Mushtaraka.
Shāfiʿī	The grandfather shares with the siblings (muqāsama); also applies al-Mushtaraka.
Ḥanbalī	The grandfather shares with the siblings (muqāsama).

Where the grandfather shares (muqāsama), he is given whichever of three outcomes is best for him: a share alongside the siblings as though he were one of them, one third of what remains after the fixed shares, or one sixth of the whole estate. The Mālikī and Shāfiʿī schools additionally apply al-Mushtaraka, letting full brothers share the maternal siblings’ third.

The calculator computes all four schools and tells you, for the family you entered, whether they agree or differ — and if they differ, you can switch schools to see exactly which heir’s share changes. For a small number of rare compositions (such as a grandfather competing with both full and paternal siblings, al-muʿādda), it defers all four schools to a scholar’s review rather than show a result it is not certain of.

See it in practice

• The calculator — try a family of your own.
• Test cases — every rule above, worked through with real numbers.