Some online video players give you the option to add or subtract delay e.g. by ±0.5s to subtitles to manually sync them to the video currently playing. However I become functionally dyslexic when it comes to actually figuring out how much delay has to be added. I end up randomly adding or subtracting delay and make it work through trial and error.
Is there some rule of thumb I could follow instead to systematically sync subtitles?


By default, they are synced by the subtitle creator. I have only had to modify probably 2 videos ever, in my life.
The rule of thumb is: don’t mess with the syncing. It’s already synced.
I don’t know that I’ve ever seen subtitles synced correctly outside of streaming services. You must have a different setup to me.
I think the problem arises mostly from trying to add subtitles to arrrr creatively acquired videos where the settings of the creator were not adhered to in the strictest sense.
I mean, I totally wouldn’t know about that myself, I just heard about it online.
It also arises simply from digital copies of DVDs that don’t come with subtitles. Which I unfortunately know too much about.
Unfortunately from where I watch movies it is pretty common for the stream and the subtitles to not sync by default as they come from different sources, so syncing them manually is inevitable.