The years · 30 of 60
癸巳 — Guǐ sì. Water above, the Snake beneath.
In BaZi the year turns at Li Chun (立春), the solar term that opens spring, computed from the sun's position rather than the calendar's round number. The Water Snake year runs from 4 February 2013 to 3 February 2014. Born in January or early February 2013? Your year animal is almost certainly the one before — check 2012. Many sites get this wrong by assuming 1 January; the date above is computed, and the engine that computed it also resolves the timezone your birthplace was actually keeping.
The Snake returns every twelve years (2001, 2025), but the full 癸巳 pillar only every sixty (1953). The same sixty names mark the days as well: there is a 癸巳 day every sixty days.
The year pillar is the part of a chart most people know, and the part that says least. Compute all four pillars, in your browser, with nothing sent anywhere.