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DNA share calculator
Pick a relationship and see the average autosomal DNA you'd share — both as a percentage and in centiMorgans (cM). The actual amount varies; the range column shows what's typical.
Average
100%
6,800 cM
Typical range
6,800 – 6,800 cM
| Relationship | Average | Typical range (cM) |
|---|---|---|
| Identical twin | 100% · 6,800 cM | 6,800 – 6,800 |
| Parent / child | 50% · 3,485 cM | 3,330 – 3,720 |
| Full sibling | 50% · 2,613 cM | 2,209 – 3,384 |
| Grandparent / grandchild | 25% · 1,766 cM | 1,156 – 2,311 |
| Aunt / uncle / niece / nephew | 25% · 1,741 cM | 1,201 – 2,282 |
| Half sibling | 25% · 1,759 cM | 1,160 – 2,436 |
| First cousin | 12.5% · 866 cM | 396 – 1,397 |
| First cousin once removed | 6.25% · 433 cM | 102 – 980 |
| Second cousin | 3.13% · 229 cM | 41 – 592 |
| Third cousin | 0.78% · 73 cM | 0 – 234 |
Why does this vary?
Autosomal DNA recombines randomly each generation. Identical twins share 100%; everyone else inherits a different mix. The numbers shown are averages from the International Society of Genetic Genealogy (ISOGG); actual results from a DNA test can sit anywhere within the range, and identical twin pairs and parent-child pairs are the most predictable.
Download the reference table
Get the full ISOGG averages and ranges as CSV or JSON to drop into a spreadsheet, slide, or your own analysis.
Drop a CSV or JSON file, or click to choose
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