Nanakshahi

1. This calendar is named after Guru Nanak Sahib, and its year 1 starts in 1469 CE - the year of birth of Guru Sahib. The year 533 Nanakshahi (current) begins on 1 Chet Nanakshahi, 14 March, 2001.

2. Based on length of Tropical year 365d 5h 48m 45s

3. Days in months 31 or 30; first five months contain 31 days each and last seven 30 days each -a very simple rule to remember.

4. Fixed leap year rule -last month to have 1 extra day every four years

5. Fixed dates of Sangrands in Common Era

6. Permanent relation between seasons and months; will stay according to Gurbani

7. Gurpurbs on fixed dates according to both Nanakshahi and Common Era calendars

8. All Gurpurbs occur once every year, according to both NS and CE calendars.

9. No 'unclean' month in the year. No month or day is 'clean' or 'unclean' according to Gurbani

10. Gurpurbs fixed according to solar dates e.g. 23 Poh for Parkash of Guru Gobind Singh Sahib, and 23 Poh will always occur on 5th January.

Bikrami

1. This Samvat is named after Maharaja Bikramajit who is supposed to have reigned Ujjain more than 2000 years ago. Historians are not unanimous that such a Maharaja whose name has been appended to this Samvat was not a fictitious person. The first mention of the Bikrami Samvat in inscriptions does not occur until circa 800 years after the supposed reign of Bikramajit The year 2058 Bikrami (completed) begins on Chet Sudi 1, 26 March 2001CE

2. Based on Sidereal year 365d 6h 9m 10s, but some panchang editors still use Surya Siddhanta length of the year - 365d 6h 12m 36s. This erroneous length (Surya Siddhanta) was the one prevalent in the Guru period.

3. Solar months may contain 29,30,31 or 32 days; no simple rule for determination of the number of days in a given month

4. No fixed rule for the leap year, it occurs every four years but occasionally after three years.

5. Sangrand depends on entrance of sun into 'rasis', dates of Sangrands not fixed in Common Era

6. Months will shift in seasons - on the average by 1 day per 70 / 71 years - already shift of 7 / 8 days since Guru Nanak Sahib's time

7. Gurpurb dates based on lunar tithis and change from year to year in CE calendar

8. In some years no Parkash Gurpurb of Guru Gobind Singh Sahib, while in others it occurs twice in one year of the CE calendar. In 1999 CE there was no Parkash Gurpurb of Guru Gobind Singh Sahib.

9. A 'mal mas' or 'unclean month' is added every two or three years in the lunar year to keep it in step with the solar year. In 2001CE there will be two months of lunar Asu, one mal and the other shudha. In mal month Gurpurbs cannot be celebrated. This whole thing is contrary to Gurbani.

10. Gurpurbs fixed according to lunar dates e.g Poh Sudi 7, therefore, changing from year to year in CE calendar. The lunar year contains 354 / 355 days while solar year 365 / 366 days. When 'mal mas' is added the lunar year becomes 383 / 384 days long.

In 2000 CE Poh Sudi 7 was on 13th January according to Surya Siddhanta Panchangas (UP), and on 14th January according to Punjab Panchangs. So the same Gurpurb was celebrated on two different dates by the proponents of the lunar calendar- on 13th January in Patna Sahib, and on 14th January in Punjab. Another problem of the lunar calendar is that the same 'tithi' can happen on two days or two 'tithis' can happen on one day.

Courtesy: S. Pal Singh Purewal