1st Cousin 1x Removed: Exactly Who That Is, and What Your DNA Test Is Telling You
A 1st cousin 1x removed is either your parent's first cousin or your first cousin's child. Both directions carry the same label, and both share roughly 6.25% of their DNA with you on average, which lands around 433 centimorgans on a consumer test. The "1x removed" part is shorthand for "once removed," and it means the two of you sit one generation apart on the family tree.
Most people who search for this exact phrase got it from a chart or a DNA result, not from a relative. The genealogy world writes it as 1C1R, and the "1x" is what happens when someone reads that shorthand and types it out. So if you landed here from a match list that said something you did not recognize, you are in the right place. This piece covers who the person actually is, why the DNA numbers matter more than the label, and why so many test results in this range get misread.
The Shorthand: What "1x Removed" Actually Means
"1x removed" is a typed-out version of the genealogy abbreviation 1C1R, which means first cousin once removed. The number before the C is the cousin degree. The number before the R is how many generations separate you.
Once you see the pattern, the whole notation system opens up:
| Shorthand | Written out | What it means |
|---|---|---|
| 1C | First cousin | Same generation, shared grandparents |
| 1C1R | First cousin once removed | One generation apart |
| 1C2R | First cousin twice removed | Two generations apart |
| 2C | Second cousin | Same generation, shared great-grandparents |
| 2C1R | Second cousin once removed | One generation apart |
| 3C2R | Third cousin twice removed | Two generations apart |
The critical thing people get wrong: "removed" describes a vertical gap, not emotional distance and not marriage. It has nothing to do with how well you know the person or whether they married in. It is pure generational bookkeeping.
Who a 1st Cousin 1x Removed Actually Is
There are exactly two ways to be someone's first cousin once removed, and they are mirror images of each other.
Direction one, going up. Your parent's first cousin is your first cousin once removed. Your mother has a first cousin named Denise. Denise is your first cousin once removed. So is Denise's brother, and so is every first cousin your mother or father has.
Direction two, going down. Your first cousin's child is your first cousin once removed. Your cousin Marcus has a daughter. That daughter is your first cousin once removed.
Both people carry the identical label, because the relationship is symmetrical. If Denise is your first cousin once removed, you are hers. There is no senior or junior version of the term and no separate word for the older or younger party.
Here is the generation math laid out, using the counting rule that governs every cousin question:
- Find the closest ancestor you both descend from.
- Count generations from you up to that ancestor.
- Count generations from the other person up to the same ancestor.
- Smaller count minus 1 gives the cousin degree.
- The difference between the counts gives the number of removals.
For you and your parent's first cousin, your shared ancestors are your great-grandparents. You are three generations below them. Your parent's first cousin is two generations below them. Smaller count is 2, minus 1 gives first cousin. Difference is 3 minus 2, which is 1. First cousin, once removed.
For you and your first cousin's child, the shared ancestors are your grandparents. You are two generations below them. Your cousin's child is three. Smaller count is 2, minus 1 gives first cousin. Difference is 1. Same answer, opposite direction.
If you would rather not run the arithmetic every time, the free relationship calculator at cousinchart.com does it from two names in a couple of clicks.
Age Is Not a Clue
A 1st cousin 1x removed can easily be older than you, younger than you, or the same age. Generation and age are separate things.
This throws people constantly. If your grandmother was the eldest of nine and her youngest sibling had children late, that younger sibling's grandchild could be your age while sitting a generation below you on the chart. In large families with wide spacing, a first cousin once removed being twenty years your senior or twenty years your junior is completely ordinary.
The practical consequence is that you cannot look at someone and guess. You have to count.
The DNA Numbers
First cousins once removed share about 6.25% of their DNA on average, which works out to roughly 433 centimorgans. The observed range in real, documented pairs runs from about 102 cM to around 980 cM.
That range is enormous, and it is the single most important fact in this article.
| Relationship | Avg. shared DNA | Avg. shared cM | Typical observed range (cM) |
|---|---|---|---|
| First cousin | ~12.5% | ~866 | 396–1,397 |
| Great-aunt / great-uncle | ~12.5% | ~850 | 330–1,467 |
| 1st cousin 1x removed | ~6.25% | ~433 | 102–980 |
| Half first cousin | ~6.25% | ~425 | 156–979 |
| Half aunt / half uncle | ~6.25% | ~425 | 196–1,003 |
| Second cousin | ~3.125% | ~229 | 41–592 |
| First cousin twice removed | ~3.125% | ~229 | 43–531 |
Those observed ranges come from the Shared cM Project, the crowdsourced dataset assembled by Blaine Bettinger from tens of thousands of documented relationships. It reports what people actually measure rather than what the textbook predicts, which is why the ranges are so much wider than the tidy averages suggest.
Every number above is an average across many pairs. Individual pairs vary a great deal, and that variation is normal biology rather than a testing error.
Why the spread is so wide. You inherit exactly 50% of your DNA from each parent, and that is the only fixed step in the whole system. Which 50% your parent passed down was decided by recombination, a shuffling process that happens fresh in every meiosis. Follow that shuffle through two or three more generations and the outcomes fan out dramatically. Two people who are both genuinely your first cousin once removed can differ by a factor of five or more in shared centimorgans, and neither result means anything is wrong with your paper trail.
How It Shows Up in a DNA Match List
This is the part worth reading twice. A shared cM value near 433 does not identify a first cousin once removed. It identifies a band that several different relationships occupy.
Look at the table above again. At roughly 425 to 433 cM you find first cousin once removed, half first cousin, and half aunt or half uncle sitting essentially on top of one another. Statistically, the test cannot separate them. Push toward the upper end of the 1C1R range, above 800 cM, and you start overlapping with full first cousins and great-aunts or great-uncles. Drop toward the lower end, near 102 cM, and you are overlapping with second cousins and first cousins twice removed.
This is why testing companies label matches with categories rather than conclusions. Depending on the company and the exact value, a match in this band may be presented as something like "1st cousin," "1st cousin once removed," "1st–2nd cousin," or a probability spread across several possibilities. All of those are the algorithm reporting a range, not a finding.
What actually resolves it:
- Shared matches. Look at who else this person matches among your known relatives. If they share matches with your maternal grandmother's line and not your paternal side, you have narrowed the search enormously. This is the highest-value tool in the kit and most people underuse it.
- The half-relationship possibility. If the paper trail says first cousin once removed but the cM value sits noticeably low, a half relationship somewhere in the line is a serious candidate. Half relationships halve the expected sharing.
- Age and generation clues. Not decisive on their own, but a match born in 1948 is unlikely to be your first cousin's grandchild.
- X-DNA, where the company reports it. Whether X chromosome sharing is even possible depends on the sexes of everyone in the connecting line, so the absence or presence of X sharing can rule out entire branches. Useful, but it takes some study to apply correctly.
- Trees, obviously. A match with four documented generations turns a guessing game into a lookup.
One thing that does not resolve it: the relationship label the company printed. Treat that label as a sorting bin, not an answer.
Why People Say "Second Cousin" Instead
The most common error in the entire subject is calling your parent's first cousin your second cousin. It is not. Your parent's first cousin is your 1st cousin 1x removed.
The intuition behind the mistake is understandable. People reason that if your parent's sibling's child is your first cousin, then your parent's cousin's child must be a second cousin, so the cousin themselves must be somewhere in that neighborhood too. The first half of that is correct. The second half is not.
The clean way to hold it:
- Your parent's first cousin → your first cousin once removed
- Your parent's first cousin's child → your second cousin
- Your parent's first cousin's grandchild → your second cousin once removed
The cousin number only advances when both people move down a generation together. When only one of you moves, you add a removal instead.
There is a mirror version of the same mistake going the other way. Your first cousin's child is not your second cousin either, and they are not your niece or nephew. They are your first cousin once removed. They become second cousins to your children, which is where the second cousin label finally appears.
This distinction matters practically because the DNA numbers are meaningfully different. First cousins once removed average around 433 cM. Second cousins average around 229 cM, roughly half. If you have mislabeled the relationship on paper, your DNA result will look inexplicable when the real problem is the label.
For a fuller treatment of the second cousin relationship on its own terms, see our 2nd cousin guide. If you want the definitional groundwork, the cousin definition piece covers the numbering and removal systems from the beginning. And for the far end of the same spectrum, where matches become plentiful and nearly useless, the 4th cousin guide explains what happens to these numbers five generations out.
Half, Step, and In-Law Variations
Half first cousin once removed. If the connecting siblings back at the top were half-siblings, you share one common ancestor instead of two, and expected DNA drops by roughly half, to somewhere around 3.1%. In match-list terms this pushes the relationship down into the same band second cousins occupy.
Step relationships. If the connection runs through a stepparent rather than a biological one, there is no shared ancestry and no cousin number applies at all. Nothing will show up on a DNA test, because there is nothing to show.
Cousin-in-law. Your first cousin once removed's spouse. No shared ancestry, no DNA connection, and no genealogical number.
Double relationships. In families where multiple marriages connected the same two family lines, a single person can be your first cousin once removed through one line and something else through another. Shared DNA then runs higher than any single relationship would predict. This shows up frequently in communities with a lot of intermarriage across generations, and it makes cM-based estimates unreliable in ways the standard tables do not capture.
What to Call Them Out Loud
Almost nobody says "this is my first cousin once removed" at a family gathering. Most people say "cousin," and that is fine.
The formal term earns its keep in three places: filling out genealogy software, interpreting a DNA match, and any legal or medical context where the exact degree of relationship matters. Everywhere else, "my cousin Denise" communicates more than the technically precise version.
Some families use "aunt" and "uncle" as courtesy titles for parents' cousins, which is warm and harmless as long as everyone understands it is a courtesy rather than a claim. It does become a problem in genealogy research, where a record listing someone as an aunt might actually be describing a first cousin once removed. When you are working from old documents or family interviews, always ask how the person was connected, not just what they were called.
Frequently Asked Questions
What does 1st cousin 1x removed mean?
It means first cousin once removed. The "1x" is a typed version of the genealogy shorthand 1C1R. The person is either your parent's first cousin or your first cousin's child, and the "removed" part indicates you are one generation apart on the family tree rather than on the same level.
How much DNA do first cousins once removed share?
About 6.25% on average, roughly 433 centimorgans. Documented pairs in the Shared cM Project range from about 102 cM to around 980 cM, which is a very wide spread. That variability is normal, because DNA inheritance is randomized at every step past parent to child.
Is my parent's first cousin my second cousin?
No. Your parent's first cousin is your first cousin once removed. Their child is your second cousin. The cousin number advances only when both people move down a generation together, and when just one of you moves you add a removal instead.
Can a DNA test tell the difference between a first cousin once removed and a half first cousin?
Not on the centimorgan value alone. Both average around 425 to 433 cM, so the two relationships occupy essentially the same band, along with half aunts and half uncles. Shared matches, documented trees, and in some cases X-DNA are what separate them.
Why does my first cousin once removed share more DNA than my first cousin?
Because these are averages and the ranges overlap. First cousins average about 866 cM but can measure as low as roughly 396 cM, while first cousins once removed can reach around 980 cM. When one pair lands low and another lands high, the order flips. A single inverted comparison is not evidence of a problem in your tree.
What is my first cousin once removed's child to me?
Your first cousin twice removed, if the connection is through your first cousin's line going down. If the person is your parent's first cousin, their child is your second cousin. The direction of the original relationship determines the answer, which is why it pays to note which way the removal runs.
Do first cousins once removed always show up on a DNA test?
Effectively always, yes. At an average of 433 cM, this relationship is far above the detection threshold of every major autosomal test. If a documented first cousin once removed does not appear in your match list, the likeliest explanations are that they tested with a different company or that their results are not set to be visible to matches.