Unless stated otherwise, the dates given in this volume (excluding those in bibliographical citations) are all BC. Each ancient Mesopotamian year has been given a single Julian year equivalent even though the ancient year actually encompassed parts of two Julian years, with the ancient year beginning around the time of the vernal equinox. Thus, for example, the sixteenth regnal year of Nebuchadnezzar II is indicated to be 589, although it actually ended in early 588 and, thus, events which took place late in the ancient year "589" actually took place early in the Julian year 588.
Texts edited in this volume occasionally mention contemporary dates and the charts in this section are intended to aid the reader in understanding those dates.
| I | Nisannu | March–April | VII | Tašrītu | September–October |
| II | Ayyāru | April–May | VIII | Araḫsamnu | October–November |
| III | Simānu | May–June | IX | Kislīmu | November–December |
| IV | Duʾūzu | June–July | X | Ṭebētu | December–January |
| V | Abu | July–August | XI | Šabāṭu | January–February |
| VI | Ulūlu | August–September | XII | Addaru | February–March |
| VI₂ | Intercalary Ulūlu | XII₂ | Intercalary Addaru |
Based on evidence from Babylonia, Intercalary Addaru (XII2) was sometimes placed before the "normal" twelfth month, just as it is still done today in the Jewish calendar.[[129]] This might have also been the case for Intercalary Ulūlu (VI2). A Neo-Assyrian letter from Mār-Ištar, Esarhaddon's agent in Babylonia,[[130]] concerning the interruption of a festival in Ulūlu might provide seventh-century evidence for Intercalary Ulūlu (VI2) coming before the "normal" Ulūlu. The relevant portion of that piece of correspondence reads as follows:
Although it is not explicitly stated by Mār-Ištar, one could tentatively assume that an Intercalary Ulūlu was added (last minute) before the "normal" Ulūlu, thereby causing the in-progress festival to be postponed one month so that it could be performed during the "normal" Ulūlu, rather than in the then-Intercalary Ulūlu.[[132]] Because the festival was to take place during a regularly scheduled month, the king and his advisors were keenly aware of the importance of maintaining the (various) cultic calendar(s), especially during a year in which an intercalary month was added. Therefore, it is not unreasonable to assume that "normal" Ulūlu and Addaru took place immediately before Tašrītu (VII) and Nisannu (I) respectively, rather than being separated from them by an intercalary month. This would ensure that there were no major disruptions between ceremonies and festivals that were celebrated just before the akītu-festival (New Year's festival). Should this actually have been the case during the Neo-Babylonian Period, then the revised order of the Mesopotamian month names and their modern equivalents should be:
| I | Nisannu | March–April | VII | Tašrītu | September–October |
| II | Ayyāru | April–May | VIII | Araḫsamnu | October–November |
| III | Simānu | May–June | IX | Kislīmu | November–December |
| IV | Duʾūzu | June–July | X | Ṭebētu | December–January |
| V | Abu | July–August | XI | Šabāṭu | January–February |
| VI₂ | IntercalaryUlūlu | XII₂ | Intercalary Addaru | ||
| VI | Ulūlu | August–September | XII | Addaru | February–March |
The table below for the reigns of Nabopolassar and Nebuchadnezzar II is adapted from Parker and Dubberstein, Babylonian Chronology pp. 27–28 and it attempts to precisely convert Babylonian dates to Julian ones. The dates are given as civil days, from midnight to midnight, and the dates (month/day) provided in the chart are those of the first day of each month. Intercalary months occurred in Nabopolassar's second (XII₂), fifth (VI₂), seventh (XII₂), tenth (VI₂), twelfth (XII₂), fifteenth (VI₂), nineteenth (VI₂), and twentieth (XII₂) regnal years; and Nebuchadnezzar II's second (VI₂), fifth (VI₂), seventh (VI₂), ninth (VI₂), eleventh (XII₂), fourteen (XII₂), seventeenth (XII₂), twenty-first (VI₂), twenty-third (XII₂), twenty-sixth (XII₂), twenty-eighth (XII₂), thirty-first (VI₂), thirty-third (XII₂), thirty-sixth (XII₂), forty-first (VI₂), and forty-second (XII₂) years on the throne.
| Year | BC | Nis | Aja | Sim | Duz | Abu | Ulu | U II | Taš | Ara | Kis | Kan | Šab | Add | A II |
| Nabopolassar | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Acc | 626 | 4/5 | 5/5 | 6/4 | 7/3 | 8/2 | 8/31 | 9/29 | 10/29 | 11/27 | 12/27 | 1/25 | 2/24 | ||
| 1 | 625 | 3/24 | 4/23 | 5/23 | 6/21 | 7/21 | 8/19 | 9/18 | 10/18 | 11/16 | 12/16 | 1/14 | 2/12 | ||
| 2 | 624 | 3/14 | 4/12 | 5/12 | 6/10 | 7/10 | 8/9 | 9/7 | 10/7 | 11/6 | 12/5 | 1/4 | 2/2 | 3/3 | |
| 3 | 623 | 4/2 | 5/1 | 5/31 | 6/29 | 7/29 | 8/27 | 9/26 | 10/26 | 11/25 | 12/24 | 1/23 | 2/21 | ||
| 4 | 622 | 3/22 | 4/21 | 5/20 | 6/18 | 7/18 | 8/16 | 9/15 | 10/15 | 11/14 | 12/13 | 1/12 | 2/11 | ||
| 5 | 621 | 3/11 | 4/9 | 5/9 | 6/7 | 7/6 | 8/5 | 9/3 | 10/3 | 11/2 | 12/2 | 1/1 | 1/30 | 3/1 | |
| 6 | 620 | 3/30 | 4/28 | 5/28 | 6/26 | 7/25 | 8/24 | 9/22 | 10/22 | 11/21 | 12/21 | 1/19 | 2/18 | ||
| 7 | 619 | 3/19 | 4/18 | 5/17 | 6/16 | 7/15 | 8/13 | 9/12 | 10/12 | 11/10 | 12/10 | 1/8 | 2/7 | 3/8 | |
| 8 | 618 | 4/7 | 5/7 | 6/5 | 7/5 | 8/3 | 9/1 | 10/1 | 10/31 | 11/29 | 12/28 | 1/27 | 2/25 | ||
| 9 | 617 | 3/26 | 4/25 | 5/24 | 6/23 | 7/23 | 8/21 | 9/20 | 10/19 | 11/18 | 12/17 | 1/15 | 2/14 | ||
| 10 | 616 | 3/15 | 4/14 | 5/13 | 6/12 | 7/12 | 8/11 | 9/9 | 10/9 | 11/7 | 12/7 | 1/5 | 2/3 | 3/5 | |
| 11 | 615 | 4/3 | 5/3 | 6/1 | 7/1 | 7/31 | 8/30 | 9/28 | 10/28 | 11/26 | 12/26 | 1/24 | 2/22 | ||
| 12 | 614 | 3/24 | 4/22 | 5/21 | 6/20 | 7/20 | 8/19 | 9/18 | 10/17 | 11/16 | 12/15 | 1/13 | 2/12 | 3/12 | |
| 13 | 613 | 4/11 | 5/10 | 6/8 | 7/8 | 8/7 | 9/5 | 10/5 | 11/4 | 12/3 | 1/2 | 1/31 | 3/2 | ||
| 14 | 612 | 3/31 | 4/30 | 5/29 | 6/27 | 7/27 | 8/26 | 9/24 | 10/24 | 11/22 | 12/22 | 1/21 | 2/19 | ||
| 15 | 611 | 3/21 | 4/19 | 5/19 | 6/17 | 7/16 | 8/15 | 9/13 | 10/13 | 11/11 | 12/11 | 1/10 | 2/9 | 3/10 | |
| 16 | 610 | 4/9 | 5/8 | 6/7 | 7/6 | 8/5 | 9/3 | 10/2 | 11/1 | 11/30 | 12/30 | 1/29 | 2/27 | ||
| 17 | 609 | 3/28 | 4/27 | 5/26 | 6/25 | 7/24 | 8/23 | 9/21 | 10/20 | 11/19 | 12/18 | 1/17 | 2/15 | ||
| 18 | 608 | 3/17 | 4/16 | 5/15 | 6/14 | 7/14 | 8/12 | 9/10 | 10/10 | 11/8 | 12/8 | 1/6 | 2/5 | ||
| 19 | 607 | 3/6 | 4/5 | 5/4 | 6/3 | 7/3 | 8/1 | 8/31 | 9/29 | 10/29 | 11/27 | 12/27 | 1/25 | 2/24 | |
| 20 | 606 | 3/25 | 4/24 | 5/23 | 6/22 | 7/21 | 8/20 | 9/19 | 10/18 | 11/17 | 12/17 | 1/15 | 2/13 | 3/14 | |
| 21 | 605 | 4/12 | 5/11 | 6/10 | 7/9 | 8/8 | 9/7 | 10/7 | 11/5 | 12/5 | 1/4 | 2/2 | 3/3 | ||
| Nebuchadnezzar II | |||||||||||||||
| 1 | 604 | 4/2 | 5/1 | 5/30 | 6/29 | 7/28 | 8/27 | 9/26 | 10/25 | 11/24 | 12/24 | 1/23 | 2/21 | ||
| 2 | 603 | 3/22 | 4/21 | 5/20 | 6/18 | 7/17 | 8/16 | 9/15 | 10/15 | 11/13 | 12/13 | 1/12 | 2/10 | 3/12 | |
| 3 | 602 | 4/10 | 5/10 | 6/8 | 7/7 | 8/6 | 9/4 | 10/4 | 11/3 | 12/2 | 1/1 | 1/30 | 2/29 | ||
| 4 | 601 | 3/30 | 4/28 | 5/28 | 6/26 | 7/25 | 8/24 | 9/22 | 10/22 | 11/21 | 12/20 | 1/19 | 2/17 | ||
| 5 | 600 | 3/19 | 4/17 | 5/17 | 6/15 | 7/15 | 8/13 | 9/11 | 10/10 | 11/9 | 12/9 | 1/8 | 2/6 | 3/7 | |
| 6 | 599 | 4/6 | 5/6 | 6/5 | 7/4 | 8/3 | 9/2 | 10/1 | 10/31 | 11/29 | 12/28 | 1/27 | 2/25 | ||
| 7 | 598 | 3/27 | 4/25 | 5/25 | 6/23 | 7/23 | 8/22 | 9/21 | 10/20 | 11/19 | 12/18 | 1/16 | 2/15 | 3/15 | |
| 8 | 597 | 4/13 | 5/13 | 6/11 | 7/11 | 8/10 | 9/9 | 10/9 | 11/17 | 12/6 | 1/5 | 2/3 | 3/5 | ||
| 9 | 596 | 4/3 | 5/2 | 6/1 | 6/30 | 7/30 | 8/29 | 9/28 | 10/28 | 11/26 | 12/25 | 1/24 | 2/22 | 3/24 | |
| 10 | 595 | 4/22 | 5/21 | 6/20 | 7/19 | 8/18 | 9/17 | 10/16 | 11/15 | 12/15 | 1/13 | 2/12 | 3/13 | ||
| 11 | 594 | 4/12 | 5/11 | 6/9 | 7/9 | 8/7 | 9/6 | 10/6 | 11/4 | 12/4 | 1/2 | 2/1 | 3/2 | 3/31 | |
| 12 | 593 | 4/30 | 5/29 | 6/27 | 7/27 | 8/25 | 9/24 | 10/23 | 11/22 | 12/21 | 1/20 | 2/19 | 3/21 | ||
| 13 | 592 | 4/19 | 5/19 | 6/17 | 7/17 | 8/15 | 9/13 | 10/13 | 11/11 | 12/10 | 1/9 | 2/8 | 3/10 | ||
| 14 | 591 | 4/8 | 5/8 | 6/7 | 7/6 | 8/5 | 9/3 | 10/2 | 11/1 | 11/30 | 12/29 | 1/28 | 2/27 | 3/28 | |
| 15 | 590 | 4/27 | 5/27 | 6/25 | 7/25 | 8/23 | 9/22 | 10/21 | 11/20 | 12/19 | 1/18 | 2/16 | 3/16 | ||
| 16 | 589 | 4/15 | 5/15 | 6/13 | 7/13 | 8/11 | 9/10 | 10/10 | 11/8 | 12/8 | 1/6 | 2/5 | 3/6 | ||
| 17 | 588 | 4/4 | 5/4 | 6/2 | 7/2 | 7/31 | 8/30 | 9/29 | 10/29 | 11/27 | 12/27 | 1/25 | 2/24 | 3/25 | |
| 18 | 587 | 4/23 | 5/23 | 6/21 | 7/21 | 8/19 | 9/18 | 10/18 | 11/17 | 12/16 | 1/15 | 2/13 | 3/15 | ||
| 19 | 586 | 4/13 | 5/12 | 6/11 | 7/10 | 8/8 | 9/7 | 10/7 | 11/6 | 12/6 | 1/4 | 2/3 | 3/3 | ||
| 20 | 585 | 4/2 | 5/1 | 5/30 | 6/29 | 7/28 | 8/26 | 9/25 | 10/25 | 11/24 | 12/23 | 1/22 | 2/21 | ||
| 21 | 584 | 3/22 | 4/21 | 5/20 | 6/18 | 7/18 | 8/16 | 9/14 | 10/14 | 11/13 | 12/13 | 1/11 | 2/10 | 3/11 | |
| 22 | 583 | 4/10 | 5/9 | 6/8 | 7/7 | 8/6 | 9/4 | 10/4 | 11/2 | 12/2 | 12/31 | 1/30 | 2/28 | ||
| 23 | 582 | 3/30 | 4/29 | 5/28 | 6/27 | 7/26 | 8/25 | 9/23 | 10/23 | 11/21 | 12/21 | 1/19 | 2/18 | 3/18 | |
| 24 | 581 | 4/17 | 5/16 | 6/15 | 7/15 | 8/13 | 9/12 | 10/12 | 11/10 | 12/9 | 1/8 | 2/6 | 3/7 | ||
| 25 | 580 | 4/6 | 5/5 | 6/4 | 7/4 | 8/3 | 9/1 | 10/1 | 10/31 | 11/29 | 12/28 | 1/27 | 2/25 | ||
| 26 | 579 | 3/26 | 4/25 | 5/24 | 6/23 | 7/23 | 8/22 | 9/20 | 10/20 | 11/19 | 12/18 | 1/16 | 2/15 | 3/16 | |
| 27 | 578 | 4/14 | 5/14 | 6/12 | 7/12 | 8/10 | 9/9 | 10/9 | 11/8 | 12/7 | 1/6 | 2/4 | 3/5 | ||
| 28 | 577 | 4/3 | 5/2 | 6/1 | 6/30 | 7/30 | 8/28 | 9/27 | 10/27 | 11/25 | 12/25 | 1/24 | 2/22 | 3/24 | |
| 29 | 576 | 4/22 | 5/21 | 6/20 | 7/19 | 8/18 | 9/16 | 10/16 | 11/14 | 12/14 | 1/13 | 2/11 | 3/13 | ||
| 30 | 575 | 4/12 | 5/11 | 6/9 | 7/9 | 8/7 | 9/6 | 10/5 | 11/4 | 12/3 | 1/2 | 1/31 | 3/2 | ||
| 31 | 574 | 4/1 | 4/30 | 5/30 | 6/28 | 7/28 | 8/26 | 9/25 | 10/24 | 11/22 | 12/22 | 1/20 | 2/19 | 3/20 | |
| 32 | 573 | 4/19 | 5/18 | 6/17 | 7/16 | 8/15 | 9/13 | 10/13 | 11/11 | 12/10 | 1/9 | 2/7 | 3/9 | ||
| 33 | 572 | 4/8 | 5/7 | 6/6 | 7/6 | 8/4 | 9/3 | 10/2 | 11/1 | 11/30 | 12/29 | 1/28 | 2/26 | 3/28 | |
| 34 | 571 | 4/26 | 5/26 | 6/25 | 7/24 | 8/23 | 9/22 | 10/21 | 11/20 | 12/19 | 1/18 | 2/16 | 3/17 | ||
| 35 | 570 | 4/16 | 5/15 | 6/14 | 7/13 | 8/12 | 9/10 | 10/10 | 11/9 | 12/9 | 1/7 | 2/6 | 3/6 | ||
| 36 | 569 | 4/4 | 5/4 | 6/2 | 7/1 | 7/31 | 8/30 | 9/28 | 10/28 | 11/27 | 12/27 | 1/25 | 2/24 | 3/25 | |
| 37 | 568 | 4/23 | 5/23 | 6/21 | 7/20 | 8/19 | 9/17 | 10/17 | 11/16 | 12/16 | 1/15 | 2/13 | 3/15 | ||
| 38 | 567 | 4/13 | 5/12 | 6/11 | 7/10 | 8/8 | 9/7 | 10/6 | 11/5 | 12/5 | 1/4 | 2/2 | 3/4 | ||
| 39 | 566 | 4/2 | 5/2 | 5/31 | 6/29 | 7/29 | 8/27 | 9/26 | 10/25 | 11/24 | 12/24 | 1/22 | 2/21 | ||
| 40 | 565 | 3/22 | 4/20 | 5/20 | 6/18 | 7/17 | 8/16 | 9/14 | 10/14 | 11/13 | 12/12 | 1/11 | 2/9 | ||
| 41 | 564 | 3/11 | 4/9 | 5/9 | 6/7 | 7/7 | 8/5 | 9/4 | 10/4 | 11/2 | 12/2 | 12/31 | 1/29 | 2/28 | |
| 42 | 563 | 3/29 | 4/28 | 5/28 | 6/26 | 7/26 | 8/25 | 9/23 | 10/23 | 11/21 | 12/21 | 1/19 | 2/17 | 3/19 | |
| 43 | 562 | 4/17 | 5/17 | 6/15 | 7/15 | 8/14 | 9/13 | 10/13 | 11/11 | 12/10 | 1/9 | 2/7 | 3/7 | ||
129 For details on the currently available evidence (from the reign of Nabonidus), see Magdalene, Wunsch, and Wells, Fault, Responsibility and Administrative Law pp. 464–465.
130 For a brief overview of his correspondence, see Baker, PNA 2/2 pp. 739–740 sub Mār-Issār no. 18.
131 Parpola, SAA 10 p. 295 no. 357. The translation is S. Parpola's, but with a few minor modifications to match RINBE's editorial style.
132 S. Parpola (LAS 2 pp. 284–285, commentary to no. 287) states the following: "While the intercalation of a second Ulūlu did not alter the name of the month in which the festival took place, it was necessary to postpone part of the ceremonies till the following month since the festival of Ulūlu was originally connected with the New Year's festival of Tašrītu, and it would have been unthinkable to break the sequence of cultic events leading from one festival to the other by a hiatus of a month or more."
Jamie Novotny & Frauke Weiershäuser
Jamie Novotny & Frauke Weiershäuser, ' Dating and Chronology', RIBo, Babylon 7: The Inscriptions of the Neo-Babylonian Dynasty, The RIBo Project, a sub-project of MOCCI, 2024 [/ribo/babylon7/RINBE11Introduction/DatingandChronology/]