We recommend keeping your file at 100MB's or lower. This has proven to be the most user friendly experience. With that said, there is no way to solely correlate a recordings length with the amount of MB's it will be. The total number of MB's is relative to the audio length as well as it's compression and file type. For instance, if your recording is currently a 320kbps .wav file it will be much larger than if it were a 160kbps .mp3 file. You would have to convert your audio file to the best size without compromising its quality. We typically receive full length albums that range from 40 to 60 minutes in length that are around 100mb's or less and they sound great. To further decrease the file size, we can archive the file into a .zip as well. If you are not sure how to compress or import your recording for digital delivery, please contact us and we'll help you out!