Shared cM Tool

Enter the total amount of DNA you share with a match (in centimorgans) to see the possible genealogical relationships and their probabilities, based on the Shared cM Project. Then optionally refine the result using ages and the number of shared segments — the more you tell it, the narrower the answer.

Refine your prediction (optional)

Two extra clues dramatically narrow which relationship is likely — inspired by MyHeritage's cM Explainer (ages) and SegcM by DNA‑Sci (segments).

Relationship probabilities

By total cM, based on statistics from The DNA Geek. Most likely first.

  • Enter a cM amount above to see probabilities.

Possible relationships

Relationships whose Shared cM Project range (99th percentile) includes this amount. Add ages/segments above to refine.

  • Nothing yet.
Shared cM Project © Blaine T. Bettinger (CC BY 4.0) · interactive tool by DNA Painter · probabilities via The DNA Geek.

Full relationship chart

Every relationship in the Shared cM Project v4 data, with its observed range and average. Ranges are the 99th percentile — a real relationship can still fall outside them, so treat the range as a guide rather than a hard boundary.

RelationshipRange (cM)Average (cM)
Parent3330–37203487
Child3330–37203487
Sibling2209–33842629
Half Sibling1317–23121783
Grandparent1156–23111766
Grandchild1156–23111766
Aunt / Uncle1349–21751750
Niece / Nephew1349–21751750
Great-Aunt / Uncle251–2108914
Great-Niece / Nephew251–2108910
Half Aunt / Uncle500–1446891
Half Niece / Nephew500–1446891
Great-Grandparent464–1486881
Great-Grandchild464–1486881
1C553–1225874
Half 1C137–856457
1C1R141–851439
Half Great-Aunt / Uncle125–765432
Half Great-Niece / Nephew125–765432
Great-Great-Aunt / Uncle191–885427
Great-Great-Niece / Nephew191–885427
2C46–515233
1C2R43–531229
Half 1C1R57–530226
Half GG-Aunt / Uncle12–383187
Half GG-Niece / Nephew12–383187
Half 1C2R37–360145
2C1R0–316123
1C3R0–283123
Half 2C9–397117
Half 1C3R0–19187
3C0–21774
2C2R0–26174
Half 2C1R0–34173
Half 3C0–17861
Half 2C2R0–35361
2C3R0–13957
3C1R0–17348
Half 3C1R0–16542
4C0–12735
3C2R0–11635
Half 3C2R0–9634
4C3R0–8229
4C1R0–11728
5C0–9425
4C2R0–10922
3C3R0–6922
5C1R0–7921
6C0–8621
5C2R0–4317
6C2R0–7517
6C1R0–7216
7C0–5713
7C1R0–5313
8C0–5012
5C3R0–4411

Other relationship tools

Cross-check your result — each tool uses the data a little differently.

DNA Painter — Shared cM Tool

The original visual chart with the pedigree layout and probabilities.

Open on DNA Painter →
MyHeritage — cM Explainer

Uses the two people's ages to predict a specific relationship.

Open cM Explainer →
DNA Science — SegcM

Uses total cM and number of segments for sharper predictions.

Open SegcM →

About this tool & credits

This is a reproduction of the Shared cM Project 3.0 tool v4, used by permission from Jonny Perl. The original interactive tool is at DNA Painter.

The Shared cM Project data is © Blaine T. Bettinger (The Genetic Genealogist), August 2017, released under a Creative Commons Attribution 4.0 License. The interactive version (v4, with probabilities) was created by Jonny Perl at DNA Painter; relationship probabilities are derived from The DNA Geek.

The optional Refine feature is inspired by MyHeritage's cM Explainer (age-based prediction) and SegcM by DNA‑Sci (dna-sci.com) (segment-count prediction). Our age and segment refinements are approximate heuristics (about 29 years per generation); for rigorous segment-based probabilities, use SegcM.

Predicted relationships are probabilities, not certainties — especially for distant matches, where many relationships share similar amounts of DNA.