Calculate audio duration from file size or estimate file size from duration. Perfect for planning transcription projects, podcast episodes, and audio storage.
* Based on PlainScribe's rate of $0.06666666666666667/minute
Smaller bitrates (like MP3 128kbps) result in longer durations for the same file size, but with lower audio quality.
| Format | Description | Best For | Typical Bitrate |
|---|---|---|---|
| MP3 | The most widely used lossy audio format. Excellent compatibility across all devices and platforms. | Podcasts, music streaming, general audio | 128-320 kbps |
| M4A/AAC | Apple's preferred audio format with better quality than MP3 at similar bitrates. | iTunes, Apple devices, high-quality streaming | 128-256 kbps |
| WAV | Uncompressed audio format with maximum quality and large file sizes. | Professional audio editing, archiving, studio work | ~1411 kbps (CD quality) |
| FLAC | Lossless compression format that preserves full quality while reducing file size. | Audiophiles, lossless archiving, quality-conscious users | ~900 kbps average |
| OGG | Open-source lossy format with good quality and wide support in gaming and streaming. | Games, open-source projects, web audio | 128-320 kbps |
This audio length calculator uses the relationship between file size, bitrate, and duration to estimate how long an audio file will play or how large a file will be for a given duration.
The formula is straightforward: Duration (seconds) = (File Size in KB x 8) / Bitrate (kbps). This works because bitrate represents how many kilobits of data are used per second of audio. Higher bitrates mean better quality but larger files.
Keep in mind that these are estimates. Actual file sizes may vary due to variable bitrate encoding (VBR), file headers, metadata (like album art in MP3s), and the specific encoder used.
Estimate file sizes for podcast episodes before recording to plan storage and hosting bandwidth requirements.
Calculate transcription costs before submitting files to estimate project budgets accurately.
Determine how much storage space you need for audio archives or how many hours will fit on your device.
Compare different audio formats to find the best balance between quality and file size for your needs.
Know the file size before recording to estimate upload times for cloud services or streaming platforms.
Estimate how much recording time remains on your device based on available storage space.
The calculator provides estimates based on standard bitrates. Actual file sizes and durations may vary depending on variable bitrate encoding, metadata, and other factors. The calculations are most accurate for constant bitrate (CBR) encoded files.
WAV files are uncompressed audio, storing the complete audio waveform without any data reduction. MP3 uses lossy compression to remove audio data that is less perceptible to human hearing, resulting in much smaller file sizes at the cost of some audio quality.
For general listening, 128-192 kbps MP3 is usually sufficient. For higher quality music, 256-320 kbps is recommended. For professional archiving or when quality is paramount, use lossless formats like WAV or FLAC.
PlainScribe charges $4 per audio hour, about $0.067 per minute. The estimated cost shown is calculated from audio duration using that rate.
Both are lossless formats preserving full audio quality. WAV is uncompressed while FLAC uses lossless compression, typically reducing file size by 50-60% compared to WAV without any quality loss. FLAC also supports metadata tags.
Video files contain both audio and video streams, so their file sizes cannot be calculated using audio bitrates alone. However, this calculator can help estimate the audio portion of video files if you know the audio format and bitrate used.
Now that you know your audio duration and estimated cost, try PlainScribe for fast, accurate AI transcription. Start with 15 free minutes.
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