Nahual. Nagual. Nawal. Animal Spirit. Mayan Day Sign. Different people use different terms and spellings to refer to the 20 day names used by the Maya civilization in their Tzolk'in calendar (not to be confused with the Long Count calendar). Your personal nahual that is assigned to you is determined by your birth date. To find out what your personal nahual is, use the following fields to enter your birth date and then click on the "Calculate my Nahual" button for more information.