Beren's dates were subject to several revisions, and the full details of his birth and death are unclear. The dates given here are taken from various sources in volume 11 of The History of Middle-earth, especially The Grey Annals and The Tale of Years. Beren's date of birth is particularly uncertain; it is given as I 432 in a genealogy of the House of Bëor, but the other dates from that source were revised (in some cases several times), so it is far from certain whether this date was intended to stand.
At least, according the The Etymologies. (The History of Middle-earth Volume 5, The Lost Road and Other Writings III The Etymologies).