What are some effective ways to memorize Japanese dates?

There's actually a very simple trick to remembering Japanese dates. I struggled with it when I first started learning, but then I realized it becomes much easier if you break it down into two parts.

First, let's look at the "day of the month" part. Days 1 to 10 are all unique and need to be memorized: 1st (ついたち, tsuitachi), 2nd (ふつか, futsuka), 3rd (みっか, mikka)... The pronunciations for these first 10 days are all special. From the 11th onwards, it becomes regular. For example, the 11th is "じゅういちにち" (jūichinichi), which literally means "eleven days". The 12th is "じゅうににち" (jūnīnichi), and so on. However, the 20th, "はつか" (hatsuka), is another exception that needs to be memorized separately. From the 21st, it's again "にじゅういちにち" (nijūichinichi, "twenty-one days"), and this pattern of [number] + にち (nichi) generally continues until the 31st.

Next are the months, which are super simple! Japanese months are just "January, February... December" with "がつ" (gatsu) added directly. For example, January (いちがつ, ichigatsu), February (にがつ, nigatsu), March (さんがつ, sangatsu), all the way to December (じゅうにがつ, jūnigatsu). Note a small change: April is "しがつ" (shigatsu) (not よんがつ, yongatsu), and July is "しちがつ" (shichigatsu) (not なながつ, nanagatsu). Just pay a little attention to these two.

My method is: first, memorize the 11 special days – days 1 to 10 and day 20. For all other days, use the [number] + にち (nichi) pattern. Months are basically [number] + がつ (gatsu), just keep an eye out for April and July. I also practice with a calendar regularly, for instance, by writing and saying today's date every day. This way, you'll gradually get familiar with them.

Say "きょうはがつにちです" (Kyō wa [month] gatsu [day] nichi desu - Today is [month] [day]) several times, replacing the placeholders with actual numbers and repeating it ten or eight times. It's much more effective than rote memorization.