Islamic Inheritance, From the Ground Up

1. Why inheritance is fixed by revelation

In most legal systems, a person decides who receives their wealth after death, and the state fills the gap when they leave no will. Islam takes a different starting point. The bulk of a Muslim's estate is distributed according to fixed shares that Allah Himself laid down — the owner cannot simply give it all to one child, disinherit another, or favour a friend over a parent. A limited window for personal choice exists (the bequest, or waṣiyya), but it is capped at one-third and cannot go to those who already inherit.

This system, called ʿilm al-mawārīth or ʿilm al-farāʾiḍ (the science of the ordained shares), protects the vulnerable. Daughters, widows, mothers and young children are guaranteed a portion that no grieving relative's preference can erase. The Prophet ﷺ urged its study directly:

"Learn the laws of inheritance and teach them, for they are half of knowledge."— reported in Sunan Ibn Mājah

Three verses of Sūrat al-Nisāʾ (4:11, 4:12, and 4:176) carry most of the numerical detail, supplemented by the Sunnah and the consensus of the Companions. From these sources the scholars built a precise, self-consistent system — the one this guide explains and the one our calculator implements.

2. The four rights before inheritance

Not a single dirham is divided among heirs until four claims on the estate are settled, strictly in this order:

1. Funeral and burial costs. Washing, shrouding, and burial are paid first, without extravagance.
2. Debts. All outstanding debts are cleared — both debts to people (loans, unpaid wages, dowry owed) and debts to Allah that carry a financial dimension, such as unpaid zakāh or an unperformed obligatory Hajj that was funded.
3. The bequest (waṣiyya). Any valid bequest is then honoured, up to a maximum of one-third of what remains, and only to recipients who are not already Qurʾānic heirs.
4. Inheritance (mīrāth). Whatever is left — the net estate — is divided among the heirs by the rules below.

3. Who inherits: the three categories of heir

Every potential heir falls into one of three groups, and the system processes them in this order:

• Aṣḥāb al-furūḍ — the fixed-share heirs. Relatives the Qurʾān assigns a specific fraction: the spouse, parents, grandparents, daughters, and certain sisters and siblings. They are paid first.
• al-ʿaṣaba — the residuaries. Relatives, mostly through the male line, who take whatever remains after the fixed shares: sons, the father, brothers, paternal uncles and their lines. If a residuary is the only heir, they take everything.
• dhawū al-arḥām — the distant kindred. Relatives such as a daughter's children or maternal uncles, who inherit only when there are no fixed-share heirs (other than a spouse) and no residuaries.

A single person can occupy more than one category — the father, for example, may take a fixed 1/6 and the residue. Three conditions must hold for anyone to inherit: the deceased's death is established, the heir is alive at that moment, and no barrier exists. The barriers are: a difference of religion (a non-Muslim does not inherit from a Muslim and vice versa), and homicide (one who unlawfully causes the death is excluded). Slavery, historically a barrier, no longer applies.

4. The six fixed shares (furūḍ)

The Qurʾān uses just six fractions. Each is tied to particular heirs under particular conditions. The single most important condition throughout is whether the deceased left a descendant (a child or a son's child), because their presence shrinks the shares of the spouse and parents and unlocks the share of the father.

Heir	Share	Condition
Husband	1/2	No descendant
Husband	1/4	With a descendant
Wife (one or more, shared)	1/4	No descendant
Wife (one or more, shared)	1/8	With a descendant
Mother	1/3	No descendant and fewer than two siblings
Mother	1/6	With a descendant, or two or more siblings
Father	1/6	With a male descendant (plus residue if only female descendants)
One daughter	1/2	No son
Two+ daughters	2/3	No son (shared equally)
Grandmother(s)	1/6	No mother (paternal grandmother also needs no father)
One maternal sibling	1/6	No descendant, no father or grandfather
Two+ maternal siblings	1/3	Shared equally, male and female alike
Full / paternal sisters	1/2 or 2/3	As for daughters, when no blocking heir is present

Two features surprise newcomers. First, a son's daughter ("granddaughter") can take 1/6 specifically to "complete the two-thirds" alongside a single daughter — so the two together reach the 2/3 a pair of daughters would have had. Second, maternal half-siblings are the one place where male and female inherit equally; the "double share for the male" rule does not apply to them, because they inherit purely through the mother.

5. Residuary heirs (ʿaṣaba)

After the fixed shares are paid, the remainder passes to the nearest residuary. Residuaries are ranked by closeness to the deceased, and only the nearest class present takes the residue:

1. Sons (and with them, daughters, at a 2:1 ratio)
2. Grandsons through a son (and granddaughters with them)
3. The father
4. The paternal grandfather
5. Full brothers (and full sisters with them)
6. Paternal half-brothers (and their sisters)
7. Nephews, then paternal uncles, then their sons — and so on down the male line

The famous rule "for the male, the share of two females" (Qurʾān 4:11) applies within a class of residuaries — a son takes twice a daughter; a full brother twice a full sister. It is not a blanket statement that men always receive double: a mother and father can take the same 1/6; maternal half-siblings, male and female, take equal shares; and in several configurations a daughter inherits while a brother of the deceased gets nothing at all.

6. Blocking and exclusion (ḥajb)

Ḥajb is the rule that a nearer relative can reduce or entirely remove a more distant one. There are two kinds. Ḥajb al-nuqṣān (partial) reduces a share — a child's presence drops the husband from 1/2 to 1/4. Ḥajb al-ḥirmān (total) removes an heir completely. The key total-exclusion rules:

• A son blocks: the deceased's grandchildren through a son, all brothers and sisters, and (with the father) the grandfather's collateral inheritance.
• The father blocks: the grandfather, and all full and paternal siblings.
• The grandfather (when no father) blocks the maternal siblings, and — in the simpler view this site follows — the full and paternal siblings too.
• The mother blocks all grandmothers.
• A full brother blocks the paternal half-siblings.
• Any descendant (son, daughter, grandson, granddaughter) blocks the maternal half-siblings.
• Two or more daughters block a son's daughters — unless a grandson is present to make them residuaries.

This is why simply listing relatives is not enough; the order in which you remove the blocked ones determines the entire result. The calculator handles this automatically.

7. When the shares overflow: ʿawl

Occasionally the fixed shares add up to more than the whole estate. The classic example: a husband (1/2) with two full sisters (2/3). One-half plus two-thirds is seven-sixths — there is not enough estate to pay everyone in full.

The solution, established by the Companions under ʿUmar ibn al-Khaṭṭāb, is ʿawl: every heir is reduced proportionally by raising the common denominator to match the total of the shares. The half and two-thirds become 3/6 and 4/6 over a new base of 7 — so the husband takes 3/7 and the sisters 4/7. Everyone shrinks by the same proportion; no one is singled out. Our engine performs exactly this adjustment and flags it.

8. When the shares fall short: radd

The opposite can also happen: the fixed shares add up to less than the estate, and there is no residuary to absorb the surplus. For instance, a mother (1/6) and one daughter (1/2) together claim only two-thirds, leaving a third unassigned.

Here the doctrine of radd ("return") applies: the surplus is returned to the fixed-share heirs in proportion to their shares — with one exception, the spouse, who does not share in the return under the position of the majority. So the mother and daughter divide the whole estate in the ratio 1:3, giving the mother 1/4 and the daughter 3/4. If the only heir is a spouse, the classical majority does not return the surplus to them; it passes to the public treasury (bayt al-māl).

9. Worked examples

Three short cases show the machinery in motion. You can reproduce each in the calculator.

Example A — a balanced family

The deceased leaves a wife, one son, and one daughter. The wife takes 1/8 (a descendant exists). The remaining 7/8 goes to the children as residuaries, split 2:1: the son gets two parts, the daughter one. So the son receives 7/12, the daughter 7/24, the wife 3/24. Everything is accounted for.

Example B — the ʿUmariyya case

The deceased leaves a husband, father, and mother only. The husband takes 1/2. The mother takes one-third of the remainder after the husband (a special rule for this exact configuration), which is 1/6 of the estate. The father, as residuary, takes the rest — 1/3. Notice the father ends up with twice the mother, preserving the 2:1 relationship between them.

Example C — ʿawl in action

The deceased leaves a husband, two full daughters, a father, and a mother. The fixed shares are 1/4 + 2/3 + 1/6 + 1/6 = fifteen-twelfths — an overflow. After ʿawl, the common base rises from 12 to 15: the husband takes 3/15 (1/5), the two daughters 8/15 between them, and the father and mother 2/15 each. On a $240,000 estate that is $48,000, $128,000, and $32,000 each to the parents.

10. Disputed cases & a final word

The framework above commands broad agreement. A handful of configurations, however, have divided scholars since the age of the Companions:

• The grandfather with siblings (al-jadd wa-l-ikhwa) — does the grandfather block the brothers as a father would, or share with them? Abū Ḥanīfa held he blocks them; the majority let them share. This site follows the simpler blocking view and flags the case.
• al-Mushtaraka (al-Ḥimāriyya) — a husband, mother, two maternal siblings, and full brothers, where the residue is zero. ʿUmar's later ruling let the full brothers share the maternal siblings' third; others left them with nothing.
• al-Akdariyya — a specific spouse-grandfather-sister combination requiring a special recombination of shares.

No calculator should pretend these are settled. Where your situation touches them, Mawarith Pro tells you so and directs you to a qualified scholar. And for any real estate — with its debts, contested facts, and human complexity — the final word belongs to a knowledgeable person, not a piece of software. Use this guide and the tool to understand and to prepare; use a scholar to decide.