Here are this year's dates of Uposatha days as observed in Thai Buddhism (Dhammayutika-Nikāya und Mahā-Nikāya). This calendar follows the Dhammayut calculation—which, for the days marked with an asterisk*, is one day later than the Mahānikai. [1]

Astronomical calculation: According Vinaya the day starts with sunrise and not like in "modern calculation of time" at 00:00 o'clock. This starting point of a new day is in regard to the place and its elevation different. As full-moon start at the same time everywhere on earth, it is possible that the day of full-moon accrues, in accordance with the calculation of moon-phases, differently. For comparison the data of Mondphasen - Table 2018, CET (wikipedia), as the sun rise calculations of www.gaisma.com can be used. If the "day of full-moon, according to Vinaya, is meant as the day when a full-moon accrues, or a day that follows the occasion of a full-moon, could not be investigated. See also Discussions about request of Uposatha-days and Table 2016.

	Full moon	Last quarter moon	New moon	First quarter moon	Full moon	Last quarter moon
January	1	9	16	24	31 Māgha Pūjā (km,lk)	-
February	-	8	15*	23*	-	-
March	1 Māgha Pūjā (th)	9	16	24	31	-
April	-	8	15*	23*	30* Visākha Pūjā	-
May	-	8*	14	22	29	-
June	-	6	13*	21*	28*	-
July	-	6*	12	20	27 Āsaḷha Pūjā
August	-	4	11	19	26	-
September	-	3	9	17	24	-
October	-	2	9	17	24 Pavāraṇā Day	-
November	-	1	8*	16*	22 Ānāpānasati Day	30
December	-	-	7	15	22	30