Audio & Imaging
Audio Duration & Filesize Calculator
Estimate audio file sizes from duration and bitrate, compare common bitrates side by side, and see how many hours of speech or music you can store in a given amount of space. All calculations happen in your browser.
1. Enter recording duration
Tip: for a half-hour recording, use 0 hours, 30 minutes, 0 seconds.
2. Choose format & bitrate
For compressed formats (MP3, Opus, AAC, etc.), file size is effectively just bitrate × duration. Different codecs at the same kbps will be extremely close in size – the real difference is how much quality you get for that bitrate.
Presets adjust codec and bitrate for typical use cases. You can still tweak the values afterwards.
If set, you’ll see how many minutes of audio fit into this space for each bitrate.
0.0 MB
estimated at 64 kbps
Estimates use decimal megabytes (1 MB = 1 000 000 bytes). For compressed formats, size is dominated by bitrate and duration; container overhead is small. For uncompressed WAV/PCM, choose that option above and set the sample rate and channels to see how frequency affects filesize.
Bitrate comparison
| Bitrate (kbps) | Estimated size | Approx. minutes per GB* | Notes |
|---|
*If you entered a storage size above, this column shows how many minutes of audio fit into that size. Otherwise it assumes 1 GB.
FAQ: Audio formats, bitrate and frequency
Why do MP3 and Opus show the same size at the same bitrate?
This tool assumes constant average bitrate encoding. For compressed formats, file size is essentially just bitrate multiplied by duration. Different codecs at the same kbps will usually end up very close in size – what changes is how good they sound at that bitrate.
Newer codecs such as Opus generally give similar or better quality than MP3 at a lower bitrate, which is where the real storage and bandwidth savings come from.
When is MP3 a good choice?
MP3 is supported almost everywhere – phones, cars, old players, browsers – so it is often the safest choice when you need maximum compatibility. It is easy to work with and good enough for many music and spoken-word uses.
The trade-off is efficiency: compared with Opus or AAC, MP3 usually needs a higher bitrate for comparable quality, so files can be larger for the same perceived quality.
When is Opus a good choice?
Opus is a modern codec that is excellent for speech and very solid for music and streaming. It can sound good at quite low bitrates, which is great for long recordings, podcasts, meetings or streaming over limited bandwidth.
Its main downside is compatibility. Most modern browsers and apps support Opus, but some older hardware players and consumer devices do not.
When is AAC a good choice?
AAC is widely used in phones, tablets, streaming services and MP4/M4A files. It is more efficient than MP3 at the same bitrate and is well supported on modern platforms, especially in the Apple ecosystem and in many streaming players.
Like other lossy formats it permanently discards some information, and very old devices or niche hardware may not support it, but for most everyday uses AAC is a solid “modern default”.
When should I use WAV / uncompressed PCM?
Uncompressed WAV or PCM keeps all the information at the chosen bit depth and sample rate, which is ideal for editing, mastering, and archival copies where you want to avoid cumulative quality loss.
The downside is size: high sample rates and multi-channel audio can produce very large files. For distribution or long-term storage, a compressed format or lossless codec such as FLAC is often more convenient.
Does frequency (sample rate) affect file size?
Yes, for uncompressed audio it does. Higher sample rates mean more samples per second, so more data. In this calculator, selecting “Uncompressed WAV / PCM” lets you see how sample rate (frequency) and channel count change the size. For compressed formats, bitrate is the main driver of file size.