伯克盾（b'ak'tun）是玛雅历20卡盾的长纪历周期。它有144000天，约394.26年。玛雅文明的古典时期发生在目前的历法周期的第8个和第9个伯克盾。

当前（第14个）伯克盾开始于13.0.0.0.0，即GMT 2012年12月21日。在这之后还接着第14到第20个伯克盾。

A baktun (properly b'ak'tun /ˈbɑːkˌtuːn/; Mayan pronunciation: [ɓakʼ ˈtun]) is 20 katun cycles of the ancient Maya Long Count Calendar. It contains 144,000 days, equal to 394.26 tropical years. The Classic period of Maya civilization occurred during the 8th and 9th baktuns of the current calendrical cycle. The current baktun started on 13.0.0.0.0 — December 21, 2012 using the GMT correlation.