Podcast Audio Requirements: What You Need to Know
Podcast distribution platforms have specific audio requirements, and meeting them is essential for getting your show accepted, sounding professional, and delivering a smooth listening experience to your audience.
The core requirements are straightforward. Your audio file must be in a supported format, encoded at an appropriate bitrate, using a standard sample rate, and conforming to loudness standards. Getting any of these wrong can result in your podcast being rejected by directories, sounding distorted on playback, consuming excessive bandwidth for listeners, or suffering from inconsistent volume compared to other shows.
Most podcasters record in a high-quality format like WAV or AIFF within their digital audio workstation, edit the episode there, and then export or convert to a distribution format as the final step. The conversion stage is where the choices you make directly affect what your listeners hear.
Understanding the technical specifications is particularly important because podcast listening happens across a huge variety of environments and devices. Your audience might be wearing premium noise-canceling headphones on a quiet commute, listening through a car stereo on the highway, playing your show on a smart speaker in the kitchen, or using basic earbuds on a crowded subway. Your audio settings need to sound acceptable across all of these scenarios.
Let us walk through each specification in detail so you can make informed decisions for your specific show.
Recommended Formats: MP3 vs AAC for Podcasts
The two formats you should consider for podcast distribution are MP3 and AAC. Both are lossy compressed formats that deliver small file sizes suitable for streaming and downloading. Other formats like WAV, FLAC, or OGG are not recommended for podcast distribution due to either excessive file sizes or limited platform support.
MP3 is the industry standard for podcasting and the format recommended by most podcast hosting providers. Every podcast player, directory, and RSS aggregator in existence supports MP3 without exception. When you submit your podcast to Apple Podcasts, Spotify, Google Podcasts, Amazon Music, Pocket Casts, Overcast, or any other platform, MP3 will work. This universal compatibility makes MP3 the default choice for most podcasters, particularly those starting out.
AAC offers better audio quality at equivalent bitrates, which means you can achieve the same perceived quality in a smaller file or better quality at the same file size. Apple Podcasts fully supports AAC, and so does Spotify. Most modern podcast players on iOS and Android handle AAC without issues. However, some older podcast apps, web-based players, and less common platforms may not support AAC reliably.
The practical recommendation is to use MP3 for maximum compatibility unless you have a specific reason to choose AAC. If your podcast is music-heavy and you want the best possible audio quality while keeping file sizes small, AAC at 128 kbps will outperform MP3 at 128 kbps. If your podcast is primarily speech, the quality difference between MP3 and AAC at the same bitrate is negligible, and MP3's compatibility advantage becomes the deciding factor.
Some podcasters produce both formats, serving MP3 through their main RSS feed and offering AAC as an alternative. Unless you have a large technical audience that specifically requests this, the added complexity is usually not worth the effort.
Bitrate and Sample Rate Settings
Bitrate determines how much data is used to represent each second of audio, directly affecting both quality and file size. Sample rate determines how many times per second the audio waveform is measured. Both settings require careful consideration for podcast distribution.
For bitrate, the standard recommendations depend on whether your podcast is mono or stereo. For mono speech podcasts, 64 to 96 kbps MP3 is the sweet spot. This provides clear, intelligible speech without unnecessary file bloat. At 64 kbps mono, an hour-long episode is approximately 28 megabytes. At 96 kbps, it is about 43 megabytes. Most podcast hosting platforms and directories consider this range optimal for speech content.
For stereo podcasts, 128 kbps MP3 is the standard recommendation. This provides good quality for music elements, sound effects, and spatial audio while keeping file sizes reasonable. An hour-long stereo episode at 128 kbps is about 56 megabytes. If your podcast features significant music content, you might consider 192 kbps for improved fidelity, though this doubles the file size compared to 96 kbps mono.
Avoid using 320 kbps for podcasts. While this is the highest standard MP3 bitrate, it produces unnecessarily large files for spoken word content. An hour at 320 kbps is about 140 megabytes, which wastes your hosting bandwidth and your listeners' storage and data plans without providing any audible benefit for speech.
For sample rate, use 44,100 Hz (44.1 kHz). This is the CD-standard sample rate and is universally supported by all podcast platforms and players. While 48,000 Hz is common in video production, 44.1 kHz is the podcast standard. Using a non-standard sample rate can cause playback issues on some devices. If your recording was captured at 48 kHz, convert to 44.1 kHz during your export or conversion process.
Bit depth should be 16-bit for the final distributed file. Your recording and editing may use 24-bit or 32-bit float for better dynamic range during processing, but the final export should be dithered down to 16-bit. This is more than sufficient for podcast audio and keeps file sizes in check.
Mono vs Stereo: Making the Right Choice
The choice between mono and stereo has a significant impact on your podcast's file size, compatibility, and listening experience.
Mono audio uses a single audio channel, meaning the same signal is sent to both the left and right speakers or earbuds. Stereo uses two independent channels, allowing different audio content in each ear. For podcasts, this choice is more consequential than many new podcasters realize.
Mono is recommended for most speech-only podcasts. When one or more people are speaking into microphones, there is no meaningful spatial information to preserve. A mono file is exactly half the size of an equivalent stereo file at the same bitrate per channel, or it can achieve equivalent quality at half the total bitrate. This means smaller downloads, less bandwidth consumption, and lower hosting costs.
Mono also provides a more consistent listening experience across devices. A listener using a single earbud, a mono Bluetooth speaker, or a car stereo with uneven speaker balance will hear your full audio content identically in mono. A stereo podcast played through a single earbud might miss audio panned to the other channel.
Stereo is appropriate when your podcast includes music, sound design, binaural recording, or immersive audio elements that genuinely use the stereo field. A music review podcast, a sound design showcase, a narrative fiction podcast with spatial sound effects, or any show where stereo separation enhances the listener's experience benefits from stereo encoding.
If you record in stereo but your content is essentially mono (two hosts speaking into individual microphones with each voice hard-panned to one channel), convert to mono before encoding. This eliminates the scenario where a listener wearing one earbud hears only one host. True mono ensures both voices are present in both ears.
To summarize: use mono at 96 kbps for speech-only podcasts, and use stereo at 128 kbps for podcasts with meaningful stereo content. This combination optimizes the trade-off between quality and file size for each use case.
Metadata and ID3 Tags for Podcasts
Metadata embedded in your audio files helps podcast players display the correct information to listeners and is required by some distribution platforms.
MP3 files use ID3 tags to store metadata. The essential tags for podcast episodes include the title (your episode title), the artist (your podcast name or host name), the album (your podcast name), the track number (episode number), the year (publication year), the genre (set to Podcast), and any comments or description.
Episode artwork is particularly important. Apple Podcasts and most other players display episode-level artwork when available. Your episode art should be embedded as an ID3 image tag in JPEG or PNG format, with a minimum resolution of 1400 by 1400 pixels and a maximum of 3000 by 3000 pixels for Apple Podcasts compatibility. Keep the image file size reasonable, ideally under 500 kilobytes, to avoid inflating your audio file size unnecessarily.
Chapter markers are an advanced metadata feature supported by some podcast players. They allow you to define named sections within your episode, enabling listeners to jump directly to topics that interest them. Apple Podcasts supports chapter markers in both MP3 and AAC formats. Implementing chapters requires either embedding them during encoding or adding them afterward with a chapter editing tool.
The podcast RSS feed also carries metadata that supplements or overrides what is in the audio files. Your hosting platform typically manages this, but ensuring your audio file metadata is accurate prevents discrepancies between what the player shows and what the RSS feed specifies.
ConvertFree preserves existing metadata during audio conversion whenever possible. If you convert from WAV to MP3 for podcast distribution, remember that WAV has limited metadata support, so you may need to add ID3 tags to the resulting MP3 file using a tagging tool after conversion.
Platform-Specific Requirements: Apple Podcasts and Spotify
While most podcast platforms share similar requirements, the two largest distributors have specific guidelines worth understanding.
Apple Podcasts accepts MP3 and AAC audio files. For MP3, Apple recommends CBR (constant bitrate) encoding rather than VBR (variable bitrate) because some older iOS devices and podcast apps have historically had issues with VBR MP3 playback, including inaccurate duration reporting and seeking problems. The recommended bitrates are 64 kbps for mono speech, 128 kbps for stereo speech, and 160 kbps for stereo music-heavy content. Apple requires a sample rate of 44.1 kHz and supports bit depths of 16-bit. Episode artwork must be at least 1400 by 1400 pixels and no more than 3000 by 3000 pixels in JPEG or PNG format.
Apple also requires that your audio meet their loudness standard of -16 LUFS (Loudness Units Full Scale) with a -1 dB true peak ceiling. LUFS is a measurement standard that accounts for human perception of loudness across the frequency spectrum. Normalizing to -16 LUFS ensures your podcast sounds consistent in volume relative to other shows on the platform. Most DAWs and audio editors can measure and adjust LUFS levels during export.
Spotify accepts MP3, AAC, OGG Vorbis, and FLAC through its hosting partners, though the platform re-encodes all content to OGG Vorbis at various quality levels for actual delivery to listeners. This means the format you upload is not necessarily the format your audience receives. However, uploading in the highest quality format you can ensures Spotify has the best source material for its own encoding pipeline.
Spotify recommends a loudness target of -14 LUFS, which is slightly louder than Apple's -16 LUFS. Since you generally cannot upload different masters to different platforms through a single hosting provider, a practical compromise is to target -16 LUFS, which satisfies Apple's requirement and sounds good on Spotify as well. Spotify's normalization system will adjust the playback level automatically.
Both platforms have maximum file size limits imposed by hosting providers rather than the platforms themselves. Most podcast hosts limit individual episode files to 200 or 250 megabytes. At 128 kbps stereo MP3, this allows for episodes of approximately 3.5 hours, which is well beyond the length of most podcasts.
Complete Podcast Audio Conversion Workflow
Here is a complete, practical workflow for converting your podcast audio from raw recording to distribution-ready file.
Start with your edited episode in your DAW. Your recording is likely in WAV or AIFF format at 24-bit or 32-bit float, with a sample rate of 44.1 kHz or 48 kHz. All editing, mixing, noise reduction, equalization, compression, and loudness normalization should be completed before you begin the conversion process. Never apply these processing steps to an already-compressed lossy file.
Export from your DAW as a high-quality intermediate file. Export as 16-bit, 44.1 kHz WAV. If your project was at 48 kHz, enable sample rate conversion in your DAW's export settings to resample to 44.1 kHz. Apply dithering when reducing bit depth from 24-bit or 32-bit to 16-bit. This intermediate WAV file serves as your master from which you will create the final distribution file.
Convert the WAV file to your distribution format. Using ConvertFree, upload your WAV file and convert to MP3 at your chosen bitrate. For a speech-only podcast, select mono output at 96 kbps. For a stereo podcast, use 128 kbps. ConvertFree processes the conversion entirely in your browser, ensuring your unreleased episode is never uploaded to external servers. This is especially valuable for podcasters who discuss sensitive topics or want to maintain strict control over unreleased content.
Add metadata to the converted file. Using an ID3 tag editor, add your episode title, podcast name, episode number, publication year, genre (Podcast), and episode artwork. Some podcast hosting platforms handle metadata through their dashboard, in which case you may not need to embed it in the file itself.
Verify the final file. Play the converted file from beginning to end in a standard media player. Check that the audio quality is acceptable, the file is not clipped or distorted, the duration is correct, and the metadata displays properly. Listen on headphones and through speakers if possible to catch any issues that might be apparent on one playback system but not another.
Upload to your podcast hosting platform. Most hosts accept the MP3 file directly through their web interface or API. The host generates your RSS feed, distributes the episode to Apple Podcasts, Spotify, and other directories, and handles streaming delivery to listeners.
Archive your source files. Keep the original DAW project file and the intermediate WAV export. If you ever need to re-export at different settings, create a version with corrected audio, or produce a remastered edition, having the original source material is invaluable. Storage is inexpensive, and re-recording a lost episode is not.
This workflow ensures consistent, professional-quality podcast audio that meets the requirements of every major distribution platform while keeping your files private and your process efficient.