Hi, @matt-long, @coises and All, Of course, the @coises’s plugin would be the best solution, being both flexible and powerful However, @matt-long, if you don’t want to install any new plugin, here is a solution with native N++ only ! Of course, I’ll use the part of file which ONLY needs changes. But, in your personal file, the trailing part of each line will stay unchanged ! So, let’s suppose an INPUT text, like below, pasted in a new tab : 09-Jan-26 00:00:00 AM, 13-Sep-21 02:00:59 AM, 13-Jul-24 04:57:29 AM, 19-Apr-20 07:42:50 AM, 01-Mar-26 09:12:43 AM, 29-Feb-24 11:08:51 AM, 25-Jul-23 11:59:59 AM, 09-Jan-19 12:00:00 AM, 01-May-26 00:00:00 PM, 08-Oct-25 02:54:31 PM, 17-Feb-22 03:29:35 PM, 23-Sep-18 06:37:06 PM, 03-Nov-20 08:55:44 PM, 31-Aug-26 10:38:00 PM, 31-Dec-20 11:59:59 PM, 01-May-26 12:00:00 PM, Open the Replace dialog Uncheck all box options FIND (?-si)^(0(\d)|\d\d)-(.+?)-(\d\d) (\d\d):(\d\d):\d\d (AM|PM)(?=,) REPLACE (?2\2:\1)/\3/(?{4}20\4) \5\7:\6 Check the Wrap around option Select the Regular expression search mode Click on the Replace All button => You should obtain the temporary OUTPUT text below : 9/Jan/2026 00AM:00, 13/Sep/2021 02AM:00, 13/Jul/2024 04AM:57, 19/Apr/2020 07AM:42, 1/Mar/2026 09AM:12, 29/Feb/2024 11AM:08, 25/Jul/2023 11AM:59, 9/Jan/2019 12AM:00, 1/May/2026 00PM:00, 8/Oct/2025 02PM:54, 17/Feb/2022 03PM:29, 23/Sep/2018 06PM:37, 3/Nov/2020 08PM:55, 31/Aug/2026 10PM:38, 31/Dec/2020 11PM:59, 1/May/2026 12PM:00, Now, APPEND at the very end of your file, all the lines below : #Jan 1 #Feb 2 #Mar 3 #Apr 4 #May 5 #Jun 6 #Jul 7 #Aug 8 #Sep 9 #Sept 9 #Oct 10 #Nov 11 #Dec 12 #00AM 00 #01AM 01 #02AM 02 #03AM 03 #04AM 04 #05AM 05 #06AM 06 #07AM 07 #08AM 08 #09AM 09 #10AM 10 #11AM 11 #12AM 12 #00PM 12 #01PM 13 #02PM 14 #03PM 15 #04PM 16 #05PM 17 #06PM 18 #07PM 19 #08PM 20 #09PM 21 #10PM 22 #11PM 23 #12PM 00 Thus, your INPUT text is now as below : 9/Jan/2026 00AM:00, 13/Sep/2021 02AM:00, 13/Jul/2024 04AM:57, 19/Apr/2020 07AM:42, 1/Mar/2026 09AM:12, 29/Feb/2024 11AM:08, 25/Jul/2023 11AM:59, 9/Jan/2019 12AM:00, 1/May/2026 00PM:00, 8/Oct/2025 02PM:54, 17/Feb/2022 03PM:29, 23/Sep/2018 06PM:37, 3/Nov/2020 08PM:55, 31/Aug/2026 10PM:38, 31/Dec/2020 11PM:59, 1/May/2026 12PM:00, #Jan 1 #Feb 2 #Mar 3 #Apr 4 #May 5 #Jun 6 #Jul 7 #Aug 8 #Sep 9 #Sept 9 #Oct 10 #Nov 11 #Dec 12 #00AM 00 #01AM 01 #02AM 02 #03AM 03 #04AM 04 #05AM 05 #06AM 06 #07AM 07 #08AM 08 #09AM 09 #10AM 10 #11AM 11 #12AM 12 #00PM 12 #01PM 13 #02PM 14 #03PM 15 #04PM 16 #05PM 17 #06PM 18 #07PM 19 #08PM 20 #09PM 21 #10PM 22 #11PM 23 #12PM 00 Open again the Replace dialog Uncheck all box options FIND (?-si)(?|(\u\l\l|Sept)|(\d\d(?:AM|PM)))(?=(?s).+^#\1 (\d+))|(?s)^#.+ REPLACE \2 Check the Wrap around option Select the Regular expression search mode Click on the Replace All button => You should get your expected OUTPUT text : 9/1/2026 00:00, 13/9/2021 02:00, 13/7/2024 04:57, 19/4/2020 07:42, 1/3/2026 09:12, 29/2/2024 11:08, 25/7/2023 11:59, 9/1/2019 12:00, 1/5/2026 12:00, 8/10/2025 14:54, 17/2/2022 15:29, 23/9/2018 18:37, 3/11/2020 20:55, 31/8/2026 22:38, 31/12/2020 23:59, 1/5/2026 00:00, Voila ! Best Regards, guy038