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Shabad Kirtan: “Chet Basant Bhalaa Bhavar Suhaavha” by Bhai Gureemt Singh Shant Singh Ji.  Thank you Ji for the beautiful shabad.  (Source: Tarlochan S Kataria on YouTube)

By Harnaak Singh

We will now continue with the study of calendars.  We will analyse the proposed Purewal’s Mool Nanakshahi calendar.  The basis of analysis will be the document and “New Nanakshahi Calendar by Pal Singh Purewal published in Understanding Sikhism – The Research Journal.  As you can see the author of this document is Pal Singh Purewal.  So we are analysing an authentic document by Pal Singh Prewal, not a second party write out of the Purewal’s Mool Nanakshahi calendar.

Note that the Purewal’s Mool Nanakshahi was in use for Sikh Gurpurabs and key Sikh events from 2003 to 2014.

We will continue with the figure number from Part 4.  

The softwares we will use in ensuring analysis are Star Fisher and Jagannath Hora.  These programs are available for free download at



Purewal’s Mool Nanakshahi Calendar


We will analyse the document “New Nanakshahi Calendar by Pal Singh Purewal.  We assume that this document contains the crux of the Purewal’s Mool Nanakshahi Calendar.  Further we assume that there are no errors in the document, this being a document which was prepared about 17 years ago.

This document first outlines the importance of calendars in relation to religious festivals, local agriculture and that every major nations of the world have evolved their own calendar.

Then he states that Sikhs have been following the Bikrami calendar and then goes on to highlight the shortcomings of this calendar.  He then proposes his Mool Nanakshahi calendar as a replacement.

We will analyse some of Purewal’s claims in the ensuring analysis outlining our findings with supporting evidence/information in this article.  We shall assume the date specified is Gregorian unless otherwise stated in Purewal’s article.


Purewal’s Claim: According to Surya Siddhantic calculations Vaisakhi occurred on the day of Spring Equinox in 532 CE.

According to Purewal Vaisakhi the 1st day of solar month Vaisakh, occurred on Spring Equinox in 532 CE.  We have to understand what this means.  

Vaisakh starts when the sun enters the zodiac sign Taurus according to the Surya Siddhanta (Chapter 1 Clause 48 Note * Page 8), the first being CHET when sun enters zodiac sign Aries.  See Figure 28.  We interpret “the lunar month which ends when the Sun is in MESHA (stellar Aries) the first sign of zodiac is called CHAITRA” to mean that the first solar month associated with zodiac sign Aries is also called CHET (CHAITRA).  We will use that Surya Siddhanta definition in this discussion.

Fig 28: Surya Siddhanta definition of relationship between month and zodiac sign


Note that sidereal zodiac is shifting due to precession.  This we have discussed in previous parts.

According to Purewal’s claim, Vaisakhi (start of zodiac sign Taurus) occurs on Summer Equinox.  This means that Vaisakh sangrand (sidereal) has moved into the date for Tropical Aries 0 deg. 

Spring Equinox occurs on 20th/21st March yearly in the tropical calculation when the sun moves into Aries.  In the sidereal calculation due to precession, the date on which this occurs changes with time.  These tropical and sidereal calculation matched for the spring (20/21- March) equinox in 285 CE (Note that CE is the same as AD).  This was shown in Part 3.  See Figure 29.

Figure 29: Calculated position of Earth using sidereal and tropical methods on 20-March-285 AD

29 EarthON-Mar-0285AD copy

Details as follow:

The starting point of the nirayana year (sidereal year) coincided in 285 AD on March Equinox, SUN at ZERO degree ARIES which was on 20-MAR-285 10:48 PM (Star Fisher) and 20-MAR-285 10:36 PM (Jagannatha Hora).  Both methods show start of spring correctly at the Spring Equinox which is the marker for start of spring.

In 285 AD both the nirayana (sidereal) year and the tropical year show spring correctly in March.

In this year Vaisakh (Vaisakh sangrand) starts on 20-April-285 10:04 pm at 0 deg TAURUS (sidereal calculation).  

Precession causes one complete rotation of the galactic circle in 25,800 years.  Hence in 100 years the expected shift is about 1.4 days.  From 285 CE to 532 CE it is 247 years.  The expected shift during this period is 1.4 x 247/100 = 3.46 daysTherefore the Vaisakh Sangrand cannot fall on Equinox 532 CE in such a short period of time.

The spring equinox in 523 CE is on March 20 (Gregorian), at 7:12 pm (tropical calculation).  At this time the sidereal position of the sun is 26 deg 35 min PISCES.  

For Vaisakh to be at Equinox the sun must be in 0 deg ARIES (using sidereal calculation) which is the 1st of Vaisakh i.e. Vaisakhi day on the spring equinox date derived from the tropical calculation.  Using Spring Equinox date, from tropical calculation, we get the following information using sidereal calculation.  

YEAR Zodiac Sign Month
1904 BC 0 deg 28 min Taurus   VAISAKH
285 CE 0 deg 0 min Aries   CHET
2413 CE 0 deg 41 min Pisces   PHAGUN
4541 CE 1 deg 1 min Aquarius   MAAGH

Figure 30 shows the position of the earth on Spring Eqinox in 4541 CE.  Notice that using tropical calculation the earth is still at 0 deg Aries but on the same day sidereal method gives earth at 1 deg Maagh about a day past Maagh Sangrand (sidereal calculation) and lies 61 deg from 0 deg Aries which is the spring Equinox day and also Chet Sangrand (tropical calculation).  Note the movement of earth occurs in sidereal calculation due to precession. 

Note that the drawing is done with tropical earth position fixed at spring equinox and sidereal earth position moving relative to this.

Figure 30: Calculated position of Earth using sidereal and tropical methods on Spring Equinox 4541 CE

30 Earth 4541CE

The closest when Vaisakh sangrand even came near to spring equinox was in year 1904 BCE.  The next time around is when Vaisakh will come around close to 0 deg Aries spring equinox would be roughly 23,935 CE See Figure 31 which shows the expected position of earth on Spring Equinox in 23,935.  At this time the precession is just approx. 30 deg away from completing one revolution which takes about 25,800 years, when both the sidereal and tropical position of earth will again fall on Spring Equinox together. 

Figure 31: Calculated position of Earth using sidereal and tropical methods on Spring Equinox 23,935 CE

31 Earth 24K CE

So clearly the claim of Purewal that Vaisakh in 532 CE falls on Equinox day is NOT TRUE.

Purewal’s Claim: Vaisakhi dates have been shifting.

This is true.  The reason for the shift is because 1st Vaisakhi is the date when sun moves into Taurus using sidereal calculation.  Sidereal zodiac is changing due to precession.  The 1st Vaisakhi dates (Gregorian) are as follows.

1400 CE

5th April

1700 CE

9th April

1900 CE

12th April

2000 CE

13th April

2010 CE

14th April

2200 CE

16th April

Purewal’s Claim: Dates of Gurpurabs in lunar calendar (sudhi/vadhi) change from year to year in the solar calendar, adjustments have to be made with additional months every few years.  Thus Gurpurab dates can vary up 11 days on normal years and up to 19 days when intercalary month is added.

This is true The reason is because the lunar months have a different number of days from the solar month.  The lunar year is 11 days shorter than the solar year.  

We have mentioned the adjustment of the lunar year to become in line with the solar year in Part 2 and 3 but did not delve into it.  We had indicated that an intercalary month is added to do this.  It is extremely important to understand this concept and we will discuss this in depth in the following.

Every two to three years an extra month, intercalary month, is added to bring the lunar year in line with the solar year.  The lunar month starts on a new moon.  The rule for addition of intercalary month is

When a lunar month starts and ends within a one solar month an intercalary month is added after this.  The intercalary month extents the lunar month to two months.  

This is how the lunar year is compensated to keep in line with the solar year.

Let us look at the addition of an intercalary lunar month in 2004.  See Figure 32.  

Figure 32: Intercalary month SAVAN in 2004

32 Intercalary 2004

The lunar month of SAVAN started on July 17, one day after Sangrand and ended on August 15 in the solar month of SAVAN (shown by the blue arrow) which ended the next day.  The next lunar month then is the intercalary month and is also called SAVAN So SAVAN extends over two months and a major part of lunar month SAVAN lies in solar month PHADRON.  And this “flow over” of the lunar month to the next solar month continues for quite some time (reducing each month).  This can result in events based on lunar month (e.g. Guru Gobind Singh Ji’s birthday) to vary about three weeks between the earliest and latest.  Strictly speaking the lunar year with the intercalary month has 13 months.

Purewal’s Claim:  Because of movable dates, Prakash Gurpurab of Guru Gobind Singh did not occur in 1991 CE, 1993 CE and 1996 CE.  It occurred twice in 1992 and 1995.

This is a true BUT a MISLEADING BIASED statement and realistically NONSENSE.  Such a BIASED MISLEADING statement is not expected from Purewal, who considers himself an expert in “calendar” technology.  He has clearly stated that the Nanakshahi calendar the year starts with CHET and ENDS with PHAGUN.  Based on this, Guru Gobind Singh Ji’s birthday will NEVER occur twice in the same year.  This claim of his is biased towards his calendar THE MOOL NANAKSHAHI CALENDAR.  Such biased claims by any scholar are meant to mislead; eventually the scholar will be caught out and this has happened to Purewal.  


Such is far from a quality of a scholar A scholar must be completely honest when he or she wants to present his or her works for accreditation.

Purewal’s Proposal:  Base the Sikh calendar on the tropical calculation, use a fixed number of days per month and follow the leap year rules used in the Gregorian calendar.

There is merit in this proposal.  

As we have seen in earlier parts, a calendar based on tropical calculation will fix the equinoxes and solstices to the same dates thus maintaining the seasons.  This is the problem with a calendar that is based on sidereal calculation which is shifting in relation to the seasons and there will come a time when autumn will occur when it is meant to be spring and winter when it is meant to be summer.  This will be around 13,200 CE. 

Presently the start of the month is tied to the move of the sun into the zodiac sign.  Figure 33 shows the months and the corresponding days proposed by Purewal, the days based on sidereal and tropical calculation (cell shaded light red) and the Gregorian calendar days (the days/month shown are for normal years).  

Figure 33: Days per month in a normal (not leap) solar year

33 Day per month Solar year

We know that the longest days occurs closer to summer (June-August) and shortest towards winter (December-January).  Purewal’s proposed number of days is divided into the longer group (31 days) centered around May and the shorter group (30 days) around December.  This seems to be an attempt to achieve this.  The other possible reason is he has mimicked the Indian Saka Calendar days/month.  Purewal has not pointed out the advantage of doing this.  We see that there is no advantage in doing this; one day either way will not make a difference to seasons.

The number of days/month according to the Gregorian calendar seems an attempt to equalise the number of days in each quarter.  There is some merit in this from the financial perspective (generally companies have quarterly performance results – it is helpful to compare quarterly performance if the quarter is of close to equal number of days).  See Figure 34.

Figure 34: Days per quarter in a normal (not leap) solar year

34 Days Quarters

Purewal’s Claim:  Proposed fixed month start dates commencing 14-Mar for CHET.

This proposal is a statement without any substantiation Purewal does not give any basis for this proposal.  Possibly he just picked the date that CHET starts nowadays.  It would be preferable if a basis is provided for this suggestion.

Purewal’s Claim:  Complicated calendrical calculations would not be required if Gurpurabs were celebrated according to the fixed solar dates.

This claim is true at face value.  But it is very important to understand that presently the key event dates are based on lunar month/year and sidereal solar month/year.  Therefore it is essential that the conversion from the events dates from lunar and sidereal month/year is appropriately reflected in the new calendrical system.  This we believe has not been reflected correctly in the Purewal’s Mool Nanakshahi calendar.  

For example Guru Gobind Singh’s birthday was Poh Sudhi 7 in Samvat 1723 (the equivalent year is 1666/67CE.   Gurvichar article at LINK provides the analysis. 

If Purewal cannot get the key date of Guru Gobind Singh Ji’s birthday correct, the other dates may just be as incorrect.

On this basis alone the PUREWAL’S MOOL NANAKSHAHI CALENDER should, and rightly so, has been rejected. 


From this analysis it is found that Purewal’s MOOL NANAKSHAHI CALENDAR is far from being a scholarly and scientifically proposed calendar.  Thus the reason for its rejection.  

However Purewal has shown the deficiencies in the present system which still needs to be addressed and an appropriate solution found.

We will stop here as far as PUREWAL’s MOOL NANAKSHAHI calendar is concerned.  We have shown that Purewals proposal is not worthy of acceptance as a Sikh Calendar.  In the next post, we will commence to look at possible solutions to the calendar issue.

Thank you for reading.  Hope you enjoyed the discussion.  

Please do not hesitate to ask for clarification if you would like to understand further any of the concepts or information presented above.

ਵਾਹਿਗੁਰੂ ਜੀ ਕਾ ਖਾਲਸਾ ਵਾਹਿਗੁਰੂ ਜੀ ਕੀ ਫਤਹਿ

To be continued

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