Genealogy & Family
Shared DNA calculator
Percentage of DNA shared by relationship.
- Instant
- Free
- Private (processed locally)
- No sign-up
Estimate shared DNA
Choose the relationship: the tool shows the average percentage of shared DNA and the approximate equivalent in centimorgans.
Reference points
- Parent / child: 50%
- Grandparent / aunt-uncle: 25%
- First cousin: 12.5%
- Second cousin: 3.1%
Average values. cM ≈ % × 68. 100% local calculation.
Frequently asked questions
How much DNA do I share with a parent?
Exactly 50% with a parent or child. With a sibling, ~50% on average (variable).
And with a first cousin?
About 12.5% on average, i.e. ~850 cM. It halves with each further degree.
What is a centimorgan (cM)?
A unit of genetic distance. DNA tests report shared DNA in cM; this tool estimates it from the %.
Are the values exact?
They are averages. Except parent/child (exactly 50%), real sharing varies from person to person.