The modern One Piece English dub has always been infamously far behind the Japanese episode releases. This is because Funimation, now a part of Crunchyroll, didn't begin working on it until 2004. However, the One Piece anime got its start back in 1999. This five-year gap between the English dub and the Japanese subs remained the standard for a long time.
However, something has been changing about this gap in recent years. Dubbed episodes have been getting put out much faster than subbed episodes and it's causing the gap to close. The One Piece dub is less than three years behind the subs with the latest batch of episodes. At the rate things are going, it will only be a matter of time before the dub is completely caught up.
Figuring out how long it will take for the dub to catch up to the subs will require a look at how fast new dubs have been coming out. Throughout the year 2022, Episodes 759 through 914 were released in English, putting the dub right around the start of Luffy's first match with Kaidō. That makes for a total of 156 new dubbed episodes, which averages a clean 13 episodes per month.
For comparison, the subs put out Episodes 1005 through 1045 throughout 2022. That makes a total of 46 episodes; this should put their average output at around three to four episodes a month. There's still a 131-episode difference between the sub and the dub, but that difference feels far more surmountable with how fast the dub is going.
If the dub and the sub continue going at their current rate, then by the end of 2023, the dub could make it up to Episode 1070. By that same point, the sub should be up to Episode 1093 at the most. By March or even February 2024, the dub could theoretically be putting out episodes within weeks of their original Japanese broadcast. 59ce067264