Sankatahara Chaturthi & Sashti: Why These Tithis Matter

By: AstroYogam Editorial | Published: July 21, 2026

Every Tamil lunar month carries a rhythm of recurring sacred days - not grand festival spikes, but quiet, monthly vrathams that families mark year after year. Among the most widely observed are Sankatahara Chaturthi (the Krishna-paksha Chaturthi dedicated to Ganesha) and Sashti (the Shukla-paksha Shashthi dedicated to Murugan). One clears obstacles; the other strengthens protection and discipline. Together they form a practical pair in South Indian household worship.

Yet the civil date on your wall calendar is not always obvious. Sankatahara Chaturthi is anchored to moonrise, not sunrise. Sashti follows sunrise. Generic almanacs that assign every tithi at sunrise alone can shift the day by one. In this guide we explain what these tithis mean, how to observe each vratham, and how AstroYogam assigns the correct civil date using the same Drik (Thirukanitha) conventions validated against Drik Panchang.

Quick Summary: Sankatahara Chaturthi & Sashti

Sankatahara Chaturthi and Sashti are monthly tithi-based vrathams - one to Ganesha, one to Murugan - anchored differently in the Panchangam. Sankatahara Chaturthi is Krishna Chaturthi (4th day of the waning half-moon), observed when that tithi prevails at moonrise; fasting is broken only after sighting the moon. Sashti is Shukla Shashthi (6th day of the waxing half-moon), observed when that tithi prevails at sunrise; a partial fast with Murugan worship. Using sunrise for both can assign the wrong civil day - especially for Sankatahara Chaturthi. For exact dates in your city, use the AstroYogam Panchangam or Kovil Calendar - never guess from a generic calendar.

What Is a Tithi? The Lunar Day Behind Every Vratham

A Tithi is the angular distance between the Sun and the Moon, divided into 30 equal segments across one lunar month. The waxing half (Shukla paksha) runs from the day after Amavasai to Pournami (tithi 1 through 15). The waning half (Krishna paksha) runs from the day after Pournami to Amavasai (tithi 16 through 30, often spoken as Krishna 1 through 14, then Amavasai).

Both Sankatahara Chaturthi and Sashti are tithi-named vrathams - their identity comes from which lunar day prevails, not from a fixed Gregorian date. That is why they recur every month and why the correct civil date depends on when the tithi prevails at a specific anchor instant (sunrise, moonrise, or another Panchangam reference). For a fuller introduction to the five Panchangam limbs, see our guide on Vedic astrology basics and the Panchangam.

Why Sankatahara Chaturthi and Sashti Are Paired in Tamil Tradition

In many Tamil households, the monthly sacred calendar is not only about one deity - it is a balanced rhythm of clearing and strengthening.

Sankatahara Chaturthi (Sankata = difficulty, Hara = remover) is offered to Ganesha (Vinayaka), the first deity invoked before any new endeavour. The vratham is specifically about removing obstacles - practical delays, mental blocks, and the accumulated friction of daily life.

Sashti is offered to Murugan (Subramanya), the deity of courage, discipline, and protection. Where Chaturthi clears the path, Sashti builds the inner strength to walk it. Murugan worship on Sashti is especially common in Tamil Nadu, and the day is often linked with reciting the Kanda Sashti Kavasam.

These are not interchangeable festivals. They fall on different pakshas (waning vs waxing), honour different deities, and use different fasting rules. Treating them as one generic "vratham day" misses the point - each tithi carries its own timing logic in the Panchangam.

Sankatahara Chaturthi: Krishna Chaturthi at Moonrise

What Is Sankatahara Chaturthi?

Sankatahara Chaturthi is the Krishna-paksha (waning) Chaturthi - the 4th lunar day after Pournami, corresponding to absolute tithi index 19 in the AstroYogam engine. It occurs once every lunar month, always in the Krishna paksha.

Unlike the famous Vinayaka Chaturthi festival (which falls on Shukla Chaturthi in the month of Avani), Sankatahara Chaturthi is a quiet monthly observance - no public holiday, but a steady household vratham across Tamil and broader South Indian tradition.

Why Moonrise Matters (Not Sunrise)

Here is the detail most generic calendars get wrong.

AstroYogam assigns Sankatahara Chaturthi to the civil day on which Krishna Chaturthi (tithi 19) prevails at moonrise - not at sunrise. The anchor is deliberate: the core worship happens in the evening or night when the moon is sighted, and the fast is traditionally broken only after offering arghya (water) to the moon and Ganesha at moonrise.

If you assign the tithi at sunrise alone, the civil date can shift by one day compared to Drik Panchang - exactly the kind of silent error that makes families miss the vratham or break the fast on the wrong evening. AstroYogam's observance scanner is golden-tested against Drik Panchang for this anchor.

How to Observe Sankatahara Chaturthi

The following is a widely followed, customary practice - the same reference guide shown in AstroYogam's Kovil Calendar feature. Exact steps can vary by family, region, and guru lineage; treat this as a general guide, not a fixed ritual manual:

Purpose: A calm vratham to Ganesha (Vinayaka) for clearing obstacles.

Fasting: A day-long fast is customary, broken only after sighting the moon and offering worship to Ganesha at moonrise.

Steps:

1. Keep a fast through the day, remembering Vinayaka.
2. In the evening, perform Ganesha puja with durva grass, red flowers, and modakam or kozhukattai.
3. Chant Om Gam Ganapataye Namaha or the Sankatahara Ganapati stotram.
4. After the moon rises, offer arghya (water) to the moon and to Ganesha, then break the fast.

Avoid: Breaking the fast before moonrise; non-vegetarian food; alcohol; anger.

Sashti: Shukla Shashthi at Sunrise

What Is Sashti?

Sashti (Shashthi) is the Shukla-paksha Shashthi - the 6th lunar day of the waxing half-moon, corresponding to absolute tithi index 6 in the AstroYogam engine. It falls once every lunar month, always before Pournami.

In Tamil tradition, Sashti is strongly associated with Murugan - temple visits, vibhuti offering, and the Kanda Sashti Kavasam. It is also relevant in the context of Chevvai (Mars) dosham remedies, where Murugan worship on Tuesdays and Sashti days is a common propitiatory practice (see our guide on Chevvai dosham cancellation rules for the broader remedy framework).

Why Sunrise Is the Anchor

Unlike Sankatahara Chaturthi, Sashti is assigned to the civil day on which Shukla Shashthi (tithi 6) prevails at sunrise. Worship is offered through the day, especially in the morning and evening. This sunrise anchor matches the standard Drik Panchang convention for Shukla Sashti and is validated in AstroYogam's observance golden tests.

How to Observe Sashti

The steps below reflect common customary practice; as with Sankatahara Chaturthi, families and lineages vary in the finer points.

Purpose: A day of devotion to Lord Murugan, often kept as a vratham for strength and protection.

Fasting: A partial fast is customary; many take a single sattvic meal and break the fast after evening worship.

Steps:

1. Bathe at dawn and visit a Murugan temple where possible.
2. Offer flowers, vibhuti, and a simple naivedyam to Murugan.
3. Recite the Kanda Sashti Kavasam or Om Saravana Bhava.
4. Break the partial fast after evening worship with sattvic food.

Avoid: Non-vegetarian food; alcohol; anger; keeping the day without discipline or devotion.

How AstroYogam Computes the Correct Civil Date

AstroYogam does not guess vratham dates from prose or AI knowledge. The engine scans the lunar month using:

• Ayanamsa: Lahiri (Chitrapaksha) - the same convention used by Drik Panchang.
• Panchangam: Sunrise-anchored for the location you choose, with historical IANA timezone resolution.
• Moon position: Geocentric (standard earth-center coordinates).
• Observance anchors: Each vratham carries a pinned anchor - sunrise for Sashti, moonrise for Sankatahara Chaturthi - defined in the observance table and validated in golden tests against Drik Panchang.

When you open the Kovil Calendar in AstroYogam, both observances appear on the civil dates the scanner assigns. Tapping an event shows this same viratham procedure (fasting, timing, steps) reproduced verbatim - it reflects common customary practice, not an AI invention, though exact rituals can vary by family and region.

Important: This blog post explains why and how to observe these vrathams. It does not list specific civil dates, because dates vary by city and year. For the next Sankatahara Chaturthi or Sashti at your location, always check the live AstroYogam Panchangam or your Kovil Calendar - never copy a date from a generic article.

Sankatahara Chaturthi vs Sashti: At a Glance

• Paksha: Sankatahara Chaturthi is Krishna (waning); Sashti is Shukla (waxing).
• Tithi name: Sankatahara Chaturthi is Chaturthi (4th day); Sashti is Shashthi (6th day).
• Engine tithi index: Sankatahara Chaturthi is 19; Sashti is 6.
• Deity: Sankatahara Chaturthi honours Ganesha (Vinayaka); Sashti honours Murugan (Subramanya).
• Civil-date anchor: Sankatahara Chaturthi uses moonrise; Sashti uses sunrise.
• Fasting: Sankatahara Chaturthi is a full day broken at moonrise; Sashti is partial and broken after evening worship.
• Key worship time: Sankatahara Chaturthi is evening or night at moon sighting; Sashti is morning and evening.
• Frequency: Both occur once per lunar month.

Conclusion

Sankatahara Chaturthi and Sashti are not obscure festival trivia - they are recurring, practical vrathams that millions of Tamil families observe every month. Understanding the difference between a moonrise-anchored Krishna Chaturthi and a sunrise-anchored Shukla Sashti is what separates a trustworthy Panchangam from a calendar that silently shifts your vratham by a day.

Use this guide for the meaning and procedure. Use AstroYogam for the date. Check the AstroYogam Panchangam for the next Sankatahara Chaturthi and Sashti at your exact location - computed with Lahiri ayanamsa, location-specific sunrise and moonrise, and validated against Drik Panchang.

Key Takeaways

• Sankatahara Chaturthi is Krishna Chaturthi (tithi 19), dedicated to Ganesha for removing obstacles; the civil date is assigned at moonrise.
• Sashti is Shukla Shashthi (tithi 6), dedicated to Murugan for strength and protection; the civil date is assigned at sunrise.
• Both recur once every lunar month - evergreen search traffic, not one-off festival spikes.
• Generic sunrise-only assignment can put Sankatahara Chaturthi on the wrong civil day compared to Drik Panchang.
• AstroYogam's Kovil Calendar and Panchangam compute these dates from the engine; the viratham procedure (fasting, steps) reflects common customary practice, not AI-generated - details can vary by family, region, and lineage.
• Never hand-copy vratham dates from blog prose - always use the live tool for your city.