TMRCA Calculator

This program calculates the probability that two people have a certain number of generations between them, based on the standard infinite alleles formula of Walsh. It calculates both the probability of being at an exact number of "transmission events" between a certain pair of people and the cumulative probability that the actual number of transmission events is less than a certain value. It can list both result types in a table, or graph either type. In either case the horizontal axis stops at the point where the cumulative probability reaches 97.5% or 10 generations, whichever is longer. Note that the number of transmission events is essentially twice the number of generations back to the MRCA (Most Recent Common Ancestor).

Suggested values for the average mutation rate per marker per generation are given below.

FTDNA Y‑12 STR	0.0020	SMGF STR set (no 464)	0.0021	mtDNA complete genome	3·10‑6
FTDNA Y‑25 STR	0.0023	All 118 available Y STR	0.0025	autosomal, X, and Y SNPs	1·10‑8
FTDNA Y‑37 STR	0.0033	mtDNA HVR	2·10‑5
FTDNA Y‑67 STR	0.0028	mtDNA coding	2·10‑6

This program was created by J. D. McDonald and is public domain.