Voice Over Audition File Format: MP3 Settings, Size and Limits

MP3 is the audition format the platforms below name. WAV is the format you record and deliver in; MP3 is what you submit. Voice123’s own guide sorts WAV, AIFF and FLAC as uncompressed and MP3, AAC and OGG as compressed, and says MP3 and AAC suit online use. Every limit below comes from the site that sets it.

What are the Voices.com file requirements?

Voices.com sets its own audio requirements, and its help center and upload screen are the only source worth trusting for them. This page quotes no Voices.com number for that reason. Read the error text when an upload fails, and until you have the figures, use the strictest spec in the table: MP3, 44.1 kHz, 128 kbps, a simple file name, and a short file.

Match all five parameters, because Voice123 says most upload errors come from incorrect file formats or parameters. That means MP3, 44.1 kHz, a constant 96 to 128 kbps, 16-bit and mono, with peaks at −3 dB or lower on the digital scale so the platform’s own WAV-to-MP3 step has headroom.

• Level and mono belong to your recording software. Smol compresses audio; it does not normalize loudness or change channel count, so set the peak and the mono track before you export.
• Constant bitrate matters. In our WAV-to-MP3 test, Smol’s Convert path wrote variable bitrate and its Compress path wrote 192 kbps constant at defaults. We have not measured Compress at 128 kbps, so use Compress and confirm the result reads constant with the header check in audio bitrate explained.
• The audition note is a separate field with a 1,000-character limit, and Voice123 sets no daily cap on auditions, so speed matters more than polish: a clean 128 kbps file and a short note.

Use 128 kbps. It is the top of Voice123’s 96 to 128 range, it costs only 960,000 bytes a minute. Bitrate is file size per second, so the arithmetic is exact: 128,000 bits is 16,000 bytes a second.

One myth costs people time. Switching to mono does not shrink an MP3 at a fixed bitrate: in our podcast audio test, 64 kbps MP3 from a stereo source and from its mono downmix were both 514,133 bytes. Mono is required for the spec, not for the size. The size comes from the bitrate and the length.

An audition file is too large when it is still a WAV. At 44.1 kHz, 16-bit, a stereo minute is 10.58 MB, and a 48 kHz, 24-bit mono minute is 8.64 MB. Convert to MP3 at 128 kbps and the same minute is 0.96 MB.

• A 3 MB cap at 128 kbps holds 187 seconds, so a 1:30 demo has room to spare.
• If the file is already an MP3 and still too big, lower the bitrate toward 96 kbps, or trim silence in your editor first. Re-compressing an MP3 loses quality again, so go back to the WAV when you can.
• Smol sets bitrate and sample rate, not output bytes, so check the size of the file it writes against the cap.

Choose Compress, then MP3, then the bitrate. The starting points below are ours, not measured thresholds, and quality for audio comes from the bitrate you choose.

1. 1

   Export a clean WAV from your editor

   Mono, 44.1 kHz, 16-bit, peaks at −3 dB or lower. Keep this file as the master.

2. 2

   Drop the WAV, or a whole folder of takes, into Smol

   Mixed batches work, so a day of auditions goes in as one drop.

3. 3

   Choose Compress, MP3, bitrate 128, sample rate 44.1 kHz

   Use 96 kbps only if a cap forces it.

4. 4

   Run it and read the result

   Smol writes a copy with a _compressed suffix by default and leaves your original untouched. Rename the copy to the file name the client asked for.

5. 5

   Check the file before you upload

   Play it start to finish, confirm the size against the cap, then upload it. No limit is promised; the check is yours.

Scripts for unreleased campaigns and games may be confidential. Smol runs on your Mac and uploads nothing, so the take never goes through a third-party converter. Narrating books instead? See audiobook files for ACX, or podcaster audio for episodes.

Start with what you already own, because export from your editor is free and often enough.

Where Smol earns its price is repetition. Mixed batches, a Finder Quick Action and a menu bar tray mean the 128 kbps setting is one drag away instead of one dialog away. See the audio compression guide and batch audio conversion for the method.

• You need to edit: trim, de-noise, normalize or fold stereo to mono. That is a job for your recording software, and Smol does none of it.
• You record one audition a week. Export the MP3 from your editor; $29 is not worth saving one dialog.
• The deliverable is final audio for a producer. Send the WAV at the rate they ask for, such as 48 kHz, 24-bit; a lossy MP3 is the wrong thing to hand over.
• You use Windows or Linux. Smol runs on macOS only.
• You need a guaranteed byte cap on audio. Smol sets bitrate, not output size, so check each file against the limit.

Working with a team of actors on one Mac each? Team is $49 for three Macs and Enterprise is $20 a seat. Presets are saved per Mac, so each person recreates the 128 kbps setting once.