# Regexp Regular Expression to get number
**URL:** https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587
**Category:** Support
**Created:** [January 26, 2026, 12:57pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587 "2026-01-26T12:57:16Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@M4ster3](https://community.mp3tag.de/u/M4ster3)
#### Post date: [January 26, 2026, 12:57pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587/1 "2026-01-26T12:57:16Z")
Hi there,
i start this with beeing plain honest, i tried now several hours with some ChatGPT help to get this Regexp to work, but it doesn´t, so may some of you explain to a noob why this is not working in any way.
Case:
I have a huge amount of files which are particialy grouped, where the Tags in album are the same for every group.
Episode 1: Word Word
Episode 1: Word Word (←—basicaly antoher part of the whole audio group Episode 1)
Episode 2: AnotherWord Word
Episode 2: AnotherWord Word (←—basicaly antoher part of the whole audio group Episode 2)
and so on.
So now i try to extract ONLY the number to copy it to the tag “series-part”.
Chatgpt gave me this expression which i added to an action and there into tag-forma, $regexp(%album%,Episode ([0-9]+),$1) but i always end up with “Redexp Error: Regular Expression” .
Can someone explain to why this fails?
Sorry for my english and greetings from Germany
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [January 26, 2026, 1:02pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587/2 "2026-01-26T13:02:09Z")
as in regular expression each character matters to define the pattern, a real example would be helpful.
To get a number try `\d`, e.g
Convert\>Tag-Tag for "series part"
Format string: `$regexp(%album%,.*(\d+).*,$1)`
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [January 26, 2026, 1:38pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587/3 "2026-01-26T13:38:46Z")
> [@M4ster3](#):
>
> $regexp(%album%,Episode ([0-9]+),$1) but i always end up with “Redexp Error: Regular Expression” .
>
> Can someone explain to why this fails?
It fails, because the square brackets `[` and `]` are special characters in a regular expression. They have to be "escaped". In your case, you can enclose it in Mp3tag with `'` to look like this:
`$regexp(%album%,Episode ('[0-9]'+),$1)`
**(I have not checked if this expression works as expected!**
It's just the explanation for the error message:
)
Update:
One way to use your regular expression to only get the number 2 in your example would be:
`$regexp(%album%,Episode ('[0-9]+'):.+,$1)`
This only works if you leave a space between the word **Episode** and your digit(s). Then a colon has to follow and then any other character.
> [@M4ster3](#):
>
> Sorry for my english and greetings from Germany
Kein Problem. Wenn es Dir lieber ist, kannst Du auch den deutschsprachigen Teil dieses Forums verwenden: #Deutsch / German
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### Author:  [@M4ster3](https://community.mp3tag.de/u/M4ster3)
#### Post date: [January 26, 2026, 2:39pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587/4 "2026-01-26T14:39:48Z")
Thanks guys for the fast reply, really appriciate it.
> [@ohrenkino](#):
>
> Format string: `$regexp(%album%,.*(\d+).*,$1)`
In my particular case it works as intended for the first 9, but only as long as there is no second digit and no twodigit number - it fails in two cases:
Episode 10: Word Word Word —–\> Ends in a 0
Episode 5: Word Word Word (Part1) —→ Ends in a 1
Luckily the second case doesn´t apply this time, as there are only digits infront of the dash, but the twodigit problem stays.
> [@LyricsLover](#):
>
> $regexp(%album%,Episode ('[0-9]'+),$1)
Just for protocoll this ends in (example) “1: Word Word Word” - so it copies the text also.
* * *
* * *
> [@LyricsLover](#):
>
> $regexp(%album%,Episode ('[0-9]+'):.+,$1)
This works flawlessly with my case, it also even works (especialy tested it) with the second digit at the end (if there would be something like “Part 1” or such a thing)
A BIG THANKS! 👍
* * *
> [@LyricsLover](#):
>
> Kein Problem. Wenn es Dir lieber ist, kannst Du auch den deutschsprachigen Teil dieses Forums verwenden: #Deutsch / German
I´d like to ask such questions in english, as most of the germans speak english, but it would be a different story the other way around - so this way everyone can profit from this thread maybe…
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [January 26, 2026, 3:14pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587/5 "2026-01-26T15:14:57Z")
> [@M4ster3](#):
>
> In my particular case it works as intended for the first 9, but only as long as there is no second digit and no twodigit number - it fails in two cases:
That is why I asked to get a real example. Your first examples only had single digits and no digits somewhere in the string.
Try this: `$regexp(%album%,.*?(\d+).*,$1)`
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [February 25, 2026, 3:15pm UTC](https://community.mp3tag.de/t/regexp-regular-expression-to-get-number/70587/6 "2026-02-25T15:15:51Z")
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