An audio file size calculator multiplies length by bitrate: 1 minute of MP3 at 128 kbps is about 0.96 MB, while 1 minute of CD-quality stereo WAV (44.1 kHz, 16-bit) is about 10.6 MB. Enter your length and settings below to get the size, then see which upload limits it fits.
Key Takeaways
- MP3 size: kilobits per second × seconds ÷ 8 gives kilobytes. At 128 kbps, 1 hour is about 57.6 MB.
- WAV size: sample rate × bit depth × channels × seconds ÷ 8. Stereo 44.1 kHz 16-bit is about 10.6 MB a minute.
- MP3 bitrate covers all channels, so a mono and a stereo MP3 at the same bitrate are the same size. Channels matter for uncompressed WAV.
- Limits differ a lot: Gmail attachments stop at 25 MB, Spotify audio ads at 50 MB, Amazon Ads audio at 3 MB. Spotify for Creators states no size limit for episodes.
- Speech needs less than music. Apple Podcasts recommends 96–128 kbps for mono and 128–256 kbps for stereo MP3.
Calculate your audio file size
Set the length and the format. The result updates as you type, and the table underneath shows which limits the file passes. Sizes use 1 MB = 1,000,000 bytes, the way most upload pages count. Nothing is sent or saved.
Does your file pass the upload limit?
The table checks your result against each limit we could verify. “Longest length” is how long a file can run at your current settings before it reaches the size limit.
| Where | Limit | Your file | Longest length at these settings |
|---|---|---|---|
| Gmail attachment (personal account) | 25 MB | - | - |
| Spotify audio ad (MP3, WAV or OGG) | 50 MB, 192–320 kbps | - | - |
| Amazon Ads audio ad | 3 MB, 10–30 seconds | - | - |
| ACX audiobook file (MP3, 192 kbps or higher, CBR, 44.1 kHz) | 120 minutes a file | - | 120 min, whatever the size |
| Spotify for Creators episode (MP3, M4A or WAV) | No file size limit stated | No limit | Large files upload more slowly and can fail on a poor connection |
| YouTube video upload | 256 GB or 12 hours, whichever is less | Far below | Audio-only podcasts need a video wrapper to upload |
Gmail’s 25 MB covers the total size of all attachments. If you go over, Gmail removes the attachment and adds a Google Drive link instead. Amazon’s 3 MB cap is the tight one: a 30-second MP3 at 128 kbps is 0.48 MB, but 30 seconds of stereo WAV at 44.1 kHz and 16-bit is about 5.3 MB, so use MP3 for that spec.
How big is 1 minute of audio at common settings?
Use this table when you need a quick number without the calculator. MP3 rows are constant bitrate. WAV rows are uncompressed.
| Format and settings | Data rate | 1 minute | 1 hour |
|---|---|---|---|
| MP3, 64 kbps | 64 kbps | 0.48 MB | 28.8 MB |
| MP3, 96 kbps | 96 kbps | 0.72 MB | 43.2 MB |
| MP3, 128 kbps | 128 kbps | 0.96 MB | 57.6 MB |
| MP3, 192 kbps | 192 kbps | 1.44 MB | 86.4 MB |
| MP3, 256 kbps | 256 kbps | 1.92 MB | 115.2 MB |
| MP3, 320 kbps | 320 kbps | 2.40 MB | 144 MB |
| WAV, 44.1 kHz, 16-bit, mono | 705.6 kbps | 5.29 MB | 317.5 MB |
| WAV, 44.1 kHz, 16-bit, stereo | 1,411 kbps | 10.58 MB | 635 MB |
| WAV, 48 kHz, 24-bit, stereo | 2,304 kbps | 17.28 MB | 1,037 MB |
| WAV, 96 kHz, 24-bit, stereo | 4,608 kbps | 34.56 MB | 2,074 MB |
Which format and bitrate should you pick?
Choose by where the file is going. Each tab ends with a block you can copy into your brief or your export notes.
Podcast
Apple Podcasts Connect accepts WAV, FLAC or MP3. For MP3 it recommends 96–128 kbps for mono and 128–256 kbps for stereo, at 44.1 or 48 kHz. For RSS feeds it strongly recommends AAC over MP3. A 30-minute mono show at 96 kbps is about 21.6 MB.
Podcast export settings Brief
Planning a show? See how to start a podcast with AI voices.
Audiobook (ACX)
ACX requires a 192 kbps or higher CBR MP3 at 44.1 kHz, and each file must be no longer than 120 minutes. At 192 kbps, 120 minutes is about 172.8 MB, so plan on files near that size.
ACX export settings Brief
Check the levels as well in our loudness standards by platform.
Audio ad
Spotify audio ads accept MP3, WAV or OGG at 192–320 kbps, up to 50 MB. Amazon Ads audio runs 10–30 seconds in WAV, MP3 or OGG, up to 3 MB. Our audio ad specs page lists the lengths and word counts too.
Audio ad export settings Brief
Email and chat
Gmail attachments on a personal account stop at 25 MB. A 128 kbps MP3 stays under that for about 26 minutes. Send a link for anything longer. We could not verify chat app limits on their own help pages, so check the app before you rely on one.
Sharing settings Brief
Editing master
Every export from an MP3 or other lossy file loses a little more quality. Keep your highest-quality source for editing and make the MP3 last. Uncompressed 48 kHz 24-bit stereo is a common editing format and takes about 17.3 MB a minute.
Master file note Brief
Know your length and format? Paste the script into Kveeky, pick a voice, adjust speed and volume, and download an MP3.
Voice your script freeHow do you estimate file size from a script?
You can size the file before you record or generate it. Start from the words, not the audio.
- Count the words in the script and divide by your pace. At about 150 words a minute, 1,500 words run about 10 minutes. The words to minutes calculator does this for you.
- Enter that length in the calculator above.
- Pick the format the destination asks for, and the lowest bitrate it allows.
- Check the table for the limit. If the file is too large, shorten the script, lower the bitrate or split it into parts.
- Re-check the exported file in your file manager. The real size can differ by a few percent.
How Kveeky helps with voice files that fit the limit
Kveeky turns your script into a voice track you can drop into any editor, and the length is set by your words, so you can size the file before you generate it.
Try a voice on your next script free
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Frequently asked questions
How big is a 1-minute MP3?
At 128 kbps, a 1-minute MP3 is about 0.96 MB. At 64 kbps it is about 0.48 MB, and at 320 kbps about 2.4 MB.
How do you calculate audio file size?
For MP3, multiply the bitrate in kilobits per second by the seconds and divide by 8 to get kilobytes. For WAV, multiply sample rate, bit depth, channels and seconds, then divide by 8 to get bytes.
How much bigger is WAV than MP3?
CD-quality stereo WAV (44.1 kHz, 16-bit) runs at 1,411 kbps, so it is about 11 times the size of a 128 kbps MP3. WAV keeps all the detail, while MP3 discards some to save space.
Does mono or stereo change an MP3 file size?
Not at the same bitrate, because the bitrate covers the whole stream. It does change WAV, where stereo is twice the size of mono. Apple Podcasts recommends 96–128 kbps for mono MP3 and 128–256 kbps for stereo.
What is the maximum audio file size for email?
A personal Gmail account allows 25 MB of attachments in total. If you go over, Gmail adds a Google Drive link instead. Work and school accounts follow the limit their administrator sets.
Sources
- Apple Podcasts accepted formats and MP3 bitrates: Apple Podcasts for Creators, “Audio requirements”, retrieved 16 October 2026. The page states no maximum file size.
- ACX MP3 format, bitrate and 120-minute limit: ACX Help, “ACX Audio Submission Requirements”, retrieved 16 October 2026.
- Gmail 25 MB attachment limit and Drive link: Gmail Help, “Send attachments with your Gmail message”, retrieved 16 October 2026.
- Spotify audio ad formats, bitrate and 50 MB limit: Spotify Advertising, “Audio ad specs”, retrieved 16 October 2026.
- Amazon audio ad length, format and 3 MB limit: Amazon Ads, “Audio ads” ad specs, retrieved 16 October 2026.
- Spotify episode file types and no size limit: Spotify for Creators, “Publishing audio episodes”, retrieved 16 October 2026.
- YouTube upload size and length: YouTube Help, “Upload videos longer than 15 minutes”, retrieved 16 October 2026.
- The size formulas are arithmetic: bytes = bits per second ÷ 8 × seconds. They are not from a source page.
- Kveeky formats, plans and rights: Kveeky pricing, retrieved 16 October 2026.