Size Issue Question For A Modified File

I am running Audacity 3.0.3 on Windows 10. I am using iTunes to create an audio CD from a playlist which iTunes is listing as 22 songs, 1 hour and 19 minutes. Supposedly the CD will hold 80 minutes. When I try to burn it, I get a message there is not enough room on the disk. I had used Audacity many years ago on an XP I had to delete “quiet points” at the end of songs in order to squeeze more music onto the CD. It worked like a charm so I decided to take the same approach now.

However, when I pulled up a song and deleted 3 seconds off the end, the time of the song went from 4:11 to 4:08 as expected BUT the size of the file went from 3,964 KB to 4,768 KB. Is there something I need to do that I missed? Is there some setting I need to set in Audacity to get it to create a smaller file? Any help would be appreciated. Thanks.


I’m not sure 80 minutes is an exact number and you’re probably getting “too close”. Originally, the CD spec was 74 minutes (and I’m not sure how exact that was either).

BUT the size of the file went from 3,964 KB to 4,768 KB.

That’s the compressed size so it depends on the bitrate (related to the amount of compression). And audio files often contain metadata (embedded artist/album/song info) but that’s not significant unless you have embedded artwork which can be significant. It’s not important because when you make an audio CD iTunes is decompressing the audio.

Audio CDs are uncompressed at 16-bits, 44,100 samples per second and 2-channel stereo. There are 8-bits in a byte so that’s 2 x 44.1 x 2 = 176.4K bytes per second or 10.584MB per minute. There is some overhead so that’s not exact either.

Thanks for the reply but quite frankly it’s over my head. Perhaps I should have understood it, but from a simplistic point of view, I had an audio file (.mp3) that I opened in Audacity, I decreased the time of the song by deleting 3 seconds from the end, then the saved file would up larger than the original. If your reply explained why that happened, I have to admit I didn’t get it.

So let me pose my question another way - If I removed 3 seconds of play time from all 22 of my files, would that shorten the playable aspect of my files by a little over a minute, regardless of the KB size of the new audio files?