Foreword — Why this book

If you have ever opened a panchang and felt like everyone else in the room knew a language you did not — this book is for you. Words like tithi, nakshatra, yoga, karana, choghadiya, rahu kaal get used as if everyone understands them. Most of us nod along. We do not. That is fine. Almost nobody is taught this in school, and the books that do explain it usually assume you already know half the answer.

We are going to start from absolute zero. No prerequisite. No prior Sanskrit. No prior astronomy. By the time you finish Book 1, you will be able to open the panchang for any day of the year and say — out loud, in your own words — what each line means, where the number came from, which calculation it represents, and whether the timing it describes is good for what you want to do.

Who I am writing this for

This book is for four kinds of readers, and for me as the fifth.

• The curious beginner. You grew up around panchang. Your grandmother checked it before family decisions. You always wanted to ask but it felt rude to interrupt, and now there is no one left to ask.
• The student of jyotish. You are studying jyotish, vastu, ayurveda, or Jain ritual practice and you need a clean, in-order foundation that does not skip steps and does not paper over disagreements between traditions.
• The third generation in the diaspora. Your English is good, your Hindi is rusty, and your Sanskrit is a handful of festival names. You want a real bridge, not a condescending summary.
• The skeptic.You do not necessarily believe in predictions, but you are interested in how an entire civilisation built a calendar from the sky, and what the underlying math actually is. That is a legitimate reason to read this. You can take the astronomy and leave the rest. Several of the world’s best-preserved ancient astronomical observations come out of the Indian tradition; whether or not you accept the ritual layer, the observational record is a real artefact of human science.
• And me. I am writing this because I did not know most of it either. Each chapter is what I learned when I sat down and worked through the question myself.

Astronomy and astrology — they are not the same

Before we start, one separation that will save us a lot of confusion later.

Astronomy is the study of where things in the sky actually are. The Sun rises in the east. The Moon goes through phases in roughly 29.5 days. Mars takes about 687 days to go around the Sun. These are facts you can verify with a telescope or a clock, and they do not depend on what anyone believes.

Astrology is a layer of meaning placed on top of those facts. It says: the Moon being in a certain part of the sky on the day you were born influences your temperament; this hour is good for starting a journey; that hour is not. Whether you accept that layer or not is up to you. But you cannot evaluate astrology intelligently if you do not first understand the astronomy underneath it. Most arguments about astrology are really arguments where one person knows the astronomy and the other does not, or both sides do not.

A panchang is, in essence, a daily report from astronomy, with astrological and ritual commentary attached. This book teaches the astronomy first. Once you know that, the astrological layer becomes a separate question you can ask honestly.

What a panchang actually is

The word panchang means “five limbs” (पंच + अंग). It refers to the five pieces of information that, taken together, fully describe a day in the Indian traditional calendar:

1. Tithi (तिथि) — the lunar day, defined by the angle between Sun and Moon.
2. Vara (वार) — the weekday, ruled by one of seven grahas.
3. Nakshatra (नक्षत्र) — the lunar mansion the Moon currently occupies (one of 27).
4. Yoga (योग) — a specific combination derived from the longitudes of Sun and Moon.
5. Karana (करण) — half of a tithi.

Five things. That is the entire skeleton. Everything else you see in a panchang — choghadiya, muhurta, rahu kaal, abhijit, the various auspicious yogas — is either derived from these five or layered on top of them. We will take each one in its own chapter, and by the end you will see how a single day’s panchang is just the same five questions answered for that date.

A short history of Indian astronomy and calendar-making

It helps to understand that the panchang you are reading today is the end-point of a continuous tradition stretching back at least three thousand years. The vocabulary, the divisions, the calculation rules — none of them were invented at once. They were refined, checked against the sky, debated between schools, and revised repeatedly. The system is alive, and disagreements between modern panchangs almost always trace back to a real historical fork.

The earliest layer is the Vedanga Jyotisha (वेदाङ्ग ज्योतिष), attributed to the sage Lagadha and dated by most scholars to roughly 1400–1200 BCE. It is not really a textbook of astronomy; it is a manual for fixing the timing of Vedic rituals. Already in this text we find the 27 nakshatras, a five-year yuga cycle, the lunar month divided into tithis, and rules for inserting an extra month to keep lunar and solar reckoning in step. The ideas are all there in seed form.

The classical synthesis comes more than a thousand years later, in the Siddhanta period (roughly 400–1200 CE). Texts like the Surya Siddhanta (सूर्य सिद्धान्त), the works of Aryabhata (Aryabhatiya, 499 CE), Varahamihira (Pancha-Siddhantika and Brihat Samhita, ~550 CE), Brahmagupta (Brahmasphutasiddhanta, 628 CE), and Bhaskara II (Siddhanta Shiromani, 1150 CE) develop the geometry and arithmetic that makes systematic prediction possible. Aryabhata proposes that Earth rotates on its axis. Brahmagupta works out rules for negative numbers and zero in the same volumes where he computes planetary positions. The astronomy is mathematically rigorous and observation-checked.

In parallel — and this is critical for our particular panchang — the Jain karaṇa tradition develops its own calendrical literature. Jain texts such as the Suryaprajnapti (सूर्यप्रज्ञप्ति), the Chandraprajnapti (चन्द्रप्रज्ञप्ति), and later karaṇa works codify time reckoning, including the udaya tithi rule with the six-ghati condition that this very panchang follows. The Jain tradition is meticulous about astronomy because precise time reckoning is required for the strict observance of vows, fasts, and ritual practice. When we get to the tithi chapter you will see why this rule, in particular, matters.

Different regions of India also developed their own panchang styles. Today there are several living traditions — broadly the Surya-siddhanta-based panchangs of the south, the Drik (modern observational) panchangs that use current astronomical data, the Vakya panchangs preserved in Tamil-speaking regions, and various Jain and Vaishnava and regional Shaiva calendars. They use the same astronomy. They differ on small choices — which epoch to anchor calculations to, whether to use the sidereal or tropical zodiac, how to resolve a tithi that changes mid-day, and a few similar conventions. Two panchangs disagreeing by a day on a festival date is almost always one of these conventions in action, not a calculation error.

About this particular panchang

The tool you are reading on follows the Jain tradition, with the udaya tithi rule applied at the six-ghati threshold: the tithi prevailing during the first six ghatis (about two hours and twenty-four minutes) after sunrise is the tithi for the entire civil day. We use modern astronomical (drik) calculations for planetary and lunar positions, not the older karaṇa approximations, because for the level of precision we now demand they are simply more accurate. Where Jain siddhantic convention prescribes a rule (such as the six-ghati threshold), we follow that convention; where the underlying number is just “the position of the Moon at this instant,” we compute it from current astronomy.

We will spend a full section on the six-ghati rule in the tithi chapter, because it is the single biggest source of confusion when people compare two different panchang sources and find they disagree by one day on a festival.

How the book is organised

The book has two parts. You are reading Part 1.

Book 1 — Panchang. Time and sky, the five limbs in depth, the derived concepts (choghadiya, muhurta, rahu kaal, yamaganda, gulika), the auspicious and inauspicious combinations (tripushkar, dwipushkar, amrit-siddhi, sarvarth-siddhi, panchak, bhadra), and at the end, a worked example of reading a real day end-to-end.

Book 2 — Kundli. Once you can read a panchang, the natural next step is the birth chart. We will cover the major chart types (Lagna, Rashi, Navamsa, and the divisional vargas), the twelve houses (bhāva), planetary aspects and friendships, the Vimshottari dasha system, and how to actually read a kundli without faking understanding. That book will come after this one is finished.

How to read this book

A few suggestions, in order of importance.

• Read in order. Each chapter relies on the previous one. If you skip ahead you will hit a word you do not know.
• Read each chapter twice. Once to get the shape, once to actually understand it. The figures are the spine — if the prose is unclear, the figure is the answer.
• Cross-check with the live tool.When a chapter introduces a concept, open the daily panchang on this site and find that concept on a real day. Concepts that feel abstract on the page often click instantly when you see them as today’s number.
• Sanskrit terms always come paired. Every tradition-specific word appears with both English transliteration and Devanagari (देवनागरी) script. This is not decoration — many of these words have meaningful roots that get lost in transliteration. Even if you cannot read Devanagari yet, seeing the same word the same way every time will start to feel familiar, and that familiarity is the first step.
• Stop and look up unfamiliar words. If a sentence contains a Sanskrit word you have not seen, search this site for it. We try to never use a term before introducing it, but the web is full of cross-references and one will eventually slip past.

What this book is not

This is not a book of predictions. We will not tell you what colour to wear on Wednesday or which gem to buy. We will explain the underlying logic of why a particular tradition associates Wednesday with Mercury and Mercury with the colour green — so that if you choose to participate in those associations, you do so knowingly.

It is also not an academic text. There are excellent scholarly works on Indian astronomy — David Pingree’s catalogue and Kim Plofker’s history are the standards in English. We will occasionally point at them in the further-reading notes. This book is closer to an honest beginner’s explanation by someone who recently was a beginner, with enough depth that a serious student can use it as their first foundation before going to the primary sources.

Take your time. Re-read paragraphs. Look at the diagrams twice. Open the daily panchang on this site and find the thing you just read about on today’s page. Reading about a tithi and seeing today’s tithi side by side is what makes it stick.

Let us begin.