---
type: Concept
bundle: jyotisha-kala
bundle_version: 0.12.0
id: masa
title: Māsa
iast: Māsa
devanagari: मास
description: 'The lunar month of the religious calendar: about 29.53 days counted in tithis, ending at new moon (amānta) or full moon (pūrṇimānta) by region, kept solar-true by the intercalary adhika-māsa; NOT a Gregorian month, NOT a fixed thirty days, NOT regionally uniform.'
darshana:
- Jyotiṣa
text_source: Sūrya Siddhānta 1; Vedāṅga Jyotiṣa
tags:
- masa
- lunar-month
- intercalation
- calendrics
- jyotisha
not:
- term: 'a Gregorian month'
  why: 'The religious māsa is synodic and tithi-counted; its boundaries are astronomical events, not civil conventions. Festival dates computed in māsa and tithi wander through the Gregorian grid by design.'
  instead: 'Render māsa as lunar month with its ending convention stated, and keep the Sanskrit term.'
- term: 'a fixed thirty days'
  why: 'Thirty TITHIS, not thirty days: the synodic month averages about 29.53 civil days and varies. The tithi count is exact; the day count is not.'
- term: 'regionally uniform'
  why: 'Amānta months (ending at new moon) govern the south and west; pūrṇimānta months (ending at full moon) govern the north. The same tithi can sit in differently named months across regions, and calendar software that ignores the split misdates half the country’s observances.'
related:
- /concepts/tithi.md
- /concepts/samvatsara.md
- /concepts/ritu.md
timestamp: '2026-07-09'
okf_version: '0.2'
license: CC BY-SA 4.0
---

# Māsa -- मास

**Not:** a Gregorian month, a fixed thirty days, regionally uniform

## What It Actually Means

The māsa of the religious calendar is lunar: a synodic month of about 29.53 days counted as thirty tithis, named Caitra through Phālguna. Two architectures divide India: amānta months ending at new moon, dominant in the south and west, and pūrṇimānta months ending at full moon in the north, so a single tithi can belong to differently named months by region. Because twelve lunar months run about eleven days short of the solar year, an intercalary adhika-māsa is inserted roughly every 32.5 months, classically defined as a lunar month containing no saṅkrānti, holding the festivals to their seasons. Solar māsas, saṅkrānti to saṅkrānti, coexist in regional calendars.

## Audience Metaphor

A month that ends on the new moon in one province and the full moon in the next, while everyone still agrees which month it is: the name rides the Moon, not the mayor’s decree. And every two or three years the calendar hires an extra month (adhika-māsa) to pay off its solar debt.

## Citations

1. Sūrya Siddhānta 1 on lunar months and intercalation -- see [references/surya-siddhanta.md](../references/surya-siddhanta.md)
2. Vedāṅga Jyotiṣa counting 62 synodic months to the five-year yuga -- see [references/lagadha-vedanga-jyotisha.md](../references/lagadha-vedanga-jyotisha.md)
