Batak calendar is not a calendar in the modern sense of the word, but a diviner’s instrument to identify auspicious days. The 12 or 13 squares along the bamboo’s length denote the months, while the 30 running across it denote the days.
The first month of the Batak calendar is Sipaha Sada, coincide with April. The other months are: Sipaha Dua = May, Sipaha Tolu = June, Sipaha Opat = July, Sipaha Lima = August, Sipaha Onom = September, Sipaha Pitu = October, Sipaha Walu = November, Sipaha Sia = December, Sipaha Sampulu = January, Li = February, and Hurung = March.
Each month has 30 days, with certain name, beginning from the first day Artya = 1, Suma = 2, Anggara = 3, Muda = 4, Boraspati = 5, Singkora = 6, Samisara = 7, Antian Ni Aek = 8, Suma Ni Mangadop = 9, Anggara Sampulu = 10, Muda Ni Mangadop = 11, Boraspati Ni Tangkup = 12, Singkora Purnama = 13, Samisara Purasa = 14, Tula = 15, Suma Ni Holom = 16, Anggara Ni Holom = 17, Muda Ni Holom = 18, Boraspati Ni Holom = 19, Singkora Mora Turun = 20, Samisara Moraturun = 21, Antian Ni Angga = 22, Suma Ni Mate = 23, Anggara Na Begu = 24, Muda Ni Mate = 25, Boraspati Na Gok = 26, Singkora Duduk = 27, Samisara Bulan Mate = 28, Hurung = 29, Ringkar = 30.
And each hour has a name in 24 hours a day, as follows: 1 a.m. = haroro ni panangko, 2 a.m. = martahuak mirik, 3 a.m. = martahuak manuk pasadaon, 4 a.m. = bola-bola ijuk, 5 a.m. = torang ari, 6 a.m. = bincar mataniari, 7 a.m. = manyogot, 8 a.m. = tarbakta, 9 a.m. = tarbakta raja, 10 a.m. = sagang, paragakkon mangan, 11 a.m. = humara hos, 12 = hos, 1 p.m. = guling, 2 p.m. = guling dao, 3 p.m. = tolu gala, 4 p.m. = dua gala, 5 p.m. = andos potang, 6 p.m. = bot, bonom mataniari, 7 p.m. = samon, 8 p.m. = hatiha mangan, 9 p.m. = tungkap hudon, 10 p.m. = sampe modom, 11 p.m. = sampe sinok modom, 12 p.m. = tonga borngin.
The Bataks zodiacs are: Mesa = Gemini, Marsoba = Taurus, Nituna = Aries, Harahata = Cancer, Singa = Leo, Hania = Virgo, Tola = Libra, Mortiha = Scorpio, Dano = Sagitarius, Morhara = Capricornus, Morhumba = Aquarius, and Mena = Pisces
