Using the calculator

The calculator is built around two steps: say who passed away, then tap the relatives who survive them. The shares update instantly as you go — there is no “calculate” button to press and nothing to submit.

Step 1 — Who passed away?

Choose A man or A woman. This single choice does one thing only: it decides whether the surviving spouse is a wife (widow) or a husband (widower). It does not change any other share.

Enter the estate

Below that, set the Estate to divide. Type a currency symbol in the small box (up to three characters — $, £, Rs, and so on) and the total amount beside it. If you would rather not work in money at all, you can leave the default value and switch the results to show fractions only later.

Debts, funeral & bequest (waṣiyya)

An estate is not divided immediately. Open the Debts, funeral & bequest (waṣiyya) section to enter what must be settled first:

Field	What it covers
Debts owed	Everything owed to people and to God.
Funeral costs	The cost of a dignified burial.
Bequest (waṣiyya)	A gift the deceased left to someone who is not already an heir.

These are settled in order: funeral and debts first, then the bequest. A bequest is capped at one third of what remains after debts — the calculator enforces that limit automatically, so you can type any figure and it will never exceed the third. The “Net to divide” line shows you exactly how much is left to share among the heirs.

Adopted children, step-children, and unmarried partners are not heirs under the fixed-share system. A person can still provide for them through the bequest (waṣiyya), within its one-third limit.

Step 2 — Who survives them?

Tap each family member who is alive, using the small plus and minus controls to set how many of each there are. The shares recalculate the moment you change anything. Use Clear to start the family over.

The spouse and the most common relatives — children and parents — are shown first. Grandparents and siblings sit behind an Add grandparents & siblings toggle to keep the form calm; open it when you need them.

The spouse

Heir	Rule
Husband	½ with no children, ¼ with children.
Wife (up to four)	¼ with no children, ⅛ with children — shared among the wives.

If the deceased was a man you enter a Wife (and may enter up to four). If a woman, you enter a Husband.

Children

Heir	Rule
Son	Takes the residue and blocks the siblings. With daughters, a son takes the share of two.
Daughter	½ alone, ⅔ if two or more — becomes residuary alongside a son.
Son’s son (grandson)	Stands in for a son when none survives; blocked by a son.
Son’s daughter (granddaughter)	Like a daughter when there is no nearer child; blocked by a son, or by two or more daughters.

Parents

Heir	Rule
Father	⅙ with children; otherwise takes the residue.
Mother	⅓ — reduced to ⅙ with children or two or more siblings.

Grandparents

Heir	Rule
Father’s father (paternal grandfather)	Stands in for the father; with siblings the schools differ.
Father’s mother (paternal grandmother)	⅙; excluded by the mother or the father.
Mother’s mother (maternal grandmother)	⅙; excluded by the mother.

Siblings

Siblings are split into three lines, because each follows entirely different rules.

Heir	Rule
Full brother (same parents)	Takes the residue; blocked by a son, son’s son, the father, or the grandfather.
Full sister (same parents)	½ alone / ⅔ if two or more; residuary with daughters or a brother.
Paternal brother (same father)	Like a full brother, but blocked by full siblings.
Paternal sister (same father)	Like a full sister, but blocked by full siblings.
Maternal brother (same mother)	⅙ alone / ⅓ shared equally; blocked by any child, the father, or grandfather.
Maternal sister (same mother)	Shares equally with the maternal brothers — no two-to-one split.

Choosing a school of law

Beside the results sits the School of law (madhab) selector — Ḥanafī, Mālikī, Shāfiʿī, or Ḥanbalī. For almost every family the four schools give the same answer, and the calculator tells you so: “All four Sunni schools agree on this family.” When they genuinely differ — which happens mainly when a grandfather inherits alongside siblings — it flags this and invites you to switch schools to compare. (More on this in The four schools.)

Starting from an example

If you would rather see the calculator in action first, use Start from an example (the sparkle button near the top, also offered in the empty results panel). It loads a ready-made family — a wife with two sons and a daughter, a husband with three daughters, and several classic teaching cases — so you can see a full result immediately and then adjust it.

Tip: examples are the fastest way to learn the tool. Load one, watch the shares appear, then change a relative or two and see how the numbers respond.