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Family tree calculator for any two relatives
This family tree calculator names how two people are related. Choose them on the Ashworth family below, or open the chart you drew in our editor, and it gives the term in plain English, such as first cousin once removed, great-aunt, half-brother or sister-in-law, with the shared ancestor and the path drawn on the tree.
Or press two people on the chart. The next press sets person A.
Owen Lowe is the third cousin of Ruby Hart.
Ruby Hart is the third cousin of Owen Lowe.
- Degree
- 8 (civil count, 4 up and 4 down)
- Nearest shared ancestors
- Walter Ashworth and Edith Ashworth
- The path
- Ruby Hart’s mother’s father’s father’s sister’s son’s son’s son
Owen Lowe is the third cousin of Ruby Hart.
Twenty-three invented people in five generations. The family tree calculator draws the path between person A and person B in green, and a gold ring marks their nearest shared ancestor.
Four steps with the family tree calculator
The family tree calculator reads the parent, child and partner lines of a chart, so it needs no typing of generations. It works on the sample family at the top of this page or on a tree of your own.
Choose a chart
The Ashworth family is open when the page loads. To use your own tree, press Use the chart saved in this browser, or open a JSON project exported from the editor.
Pick person A
Choose a name in the first list, or press a person on the chart. Person A is the one the answer is measured from.
Pick person B
Choose the second name, or press a second person. The answer changes at once, and the swap button reverses the pair.
Read the answer
The result names person B as a relative of person A, then the reverse term, the degree, the nearest shared ancestor and the path from one to the other.
Counting up to the shared ancestor and down again
Every blood relationship runs through a shared ancestor. The family tree calculator counts the generations from person A up to the nearest ancestor both people descend from, then down to person B. Ruby Hart and Owen Lowe on the sample tree are four generations below Walter and Edith Ashworth, so they are third cousins.
When both counts are two or more, the two people are cousins. The lower count, less one, gives the degree, so two generations each way make first cousins and three make second cousins. The difference between the counts is the removal. Family Tree Magazine puts it this way, one generation of difference equals one remove, so the child of your first cousin is your first cousin once removed.
When one count is one, the relative is a brother, sister, aunt, uncle, niece or nephew, with a great- for each further generation. When one count is zero, the two are in a direct line, a parent, grandparent or great-grandparent above and a child or grandchild below. The sum of the two counts is the degree by the civil count, the method the family tree relationship terms guide uses, under which a brother is two degrees away and a first cousin four.
| Person A below the ancestor | B is a grandchild | B is a great-grandchild | B is two greats down | B is three greats down |
|---|---|---|---|---|
| A is a grandchild | First cousin | First cousin once removed | First cousin twice removed | First cousin three times removed |
| A is a great-grandchild | First cousin once removed | Second cousin | Second cousin once removed | Second cousin twice removed |
| A is two greats down | First cousin twice removed | Second cousin once removed | Third cousin | Third cousin once removed |
| A is three greats down | First cousin three times removed | Second cousin twice removed | Third cousin once removed | Fourth cousin |
Half relatives, double cousins and adoption
A half relative shares one ancestor at the top of the path instead of a couple. Harold Ashworth married twice, so Richard, his son by Joan Pike, and Susan, his daughter by Irene Cole, are half-brother and half-sister, and their children Emma and Lucy are half first cousins. The calculator calls a relationship half only when the chart records both parents on each side, because a missing parent is unknown, not absent.
Double cousins come from two brothers or sisters of one family marrying two of another. They share both sets of grandparents, and the family tree calculator names them double first cousins when the chart shows all four grandparents.
An adopted child is in law the child of the adopters. The Adoption and Children Act 2002 of England and Wales and the Uniform Probate Code followed in Minnesota both say so, so the calculator treats an adoptive line like a line by birth and adds a note. James Ashworth, adopted by Richard and Linda, is the brother of Emma and the second cousin of Kevin Lowe. Foster, donor and surrogacy lines are left out of the count.
In-laws, step-relatives and relatives by marriage
When two people share no ancestor, the family tree calculator looks for one marriage or partnership between them and names the relative from either side of it.
In-laws
The parents, grandparents and brothers and sisters of a husband or wife, and the husbands and wives of your children and siblings. Linda Ashworth is the daughter-in-law of Harold, and Paul Grant is the brother-in-law of Richard.
Step-relatives
The husband or wife of a parent who is not your parent, their children and their parents. Michael Cole came into the family when his mother Irene married Harold, so he is the stepson of Harold and the stepbrother of Richard.
Aunts and uncles by marriage
Thomas Lowe married Margaret, the aunt of Richard, so the calculator names him an uncle by marriage, which English often shortens to uncle.
Longer chains
English has no single word for the husband of a sister-in-law. The calculator then gives the chain of people in words, such as wife’s sister’s husband, and draws it on the tree.
Open your own chart in the family tree calculator
Draw your family in the editor on our homepage or on the family tree page, and the browser keeps the chart. Back on this page, Use the chart saved in this browser opens it in the family tree calculator, and a chart kept in the Studio workspace of this browser is offered too. A JSON project exported from the editor opens the same way on any computer.
Everything happens in the browser. The chart is read from this device and is not sent anywhere, and the calculator changes nothing in it. The answer can only be as complete as the chart, so a cousin whose parents are missing from the tree comes out as unrelated until the line between you is drawn.
Pairs to try on the Ashworth family
The sample family was written so that one tree holds every kind of answer. These pairs show each one.
| Person A | Person B | Person B is | Degree |
|---|---|---|---|
| Ruby Hart | Walter Ashworth | Great-great-grandfather | Four |
| Emma Hart | Margaret Lowe | Great-aunt | Four |
| Emma Hart | Alan Lowe | First cousin once removed | Five |
| Ruby Hart | Kevin Lowe | Second cousin once removed | Seven |
| Richard Ashworth | Susan Grant | Half-sister | Two |
| Richard Ashworth | Michael Cole | Stepbrother | By marriage |
| Linda Ashworth | Walter Ashworth | Grandfather-in-law | By marriage |
Questions about the family tree calculator
What once removed means
Removed counts the generations between two cousins. Your first cousin is the child of your aunt or uncle, and the child of that cousin is your first cousin once removed. The removal works both ways, so you are their first cousin once removed too.
The difference between second cousins and first cousins once removed
Second cousins are in the same generation and share great-grandparents. A first cousin once removed shares grandparents with one of you and great-grandparents with the other, so the two are one generation apart.
Great-aunt or grandaunt
Both name the sister of a grandparent. Dictionary.com gives grandaunt and great-aunt as the same relative, and the calculator notes the second form under the answer.
Whether the family tree calculator works without a chart
The family tree calculator needs the people and their lines. For two people who are not on a chart yet, add them and their parents to the Ashworth family in the editor, or start a tree of your own, and open it here.
What the family tree calculator does not do
It names relationships on a chart and counts degrees. It does not estimate shared DNA, and it gives no legal advice on marriage or inheritance, which follow the law of each country.
Where the facts come from
- Family Tree Magazine, How to calculate cousinhood First and second cousins, removals and double cousins.
- Dictionary.com, half-brother The son of either parent by another partner.
- Dictionary.com, stepbrother The son of a stepparent by an earlier marriage.
- Dictionary.com, brother-in-law The brother of a spouse and the husband of a sister.
- Dictionary.com, great-aunt The sister of a grandparent, also called grandaunt.
- Adoption and Children Act 2002, section 67 An adopted person is treated in law as the child of the adopters.
- Minnesota Statutes, section 524.2-118 A parent and child relationship exists between an adoptee and the adoptive parents.
- MyHeritage, How many times removed Half cousins through half-siblings.
Checked on 10 November 2026.
