Audio Bitrate to File Size Calculator
Estimate audio file size from bitrate and duration, shown in MB and MiB. Handy for podcasters and audio producers planning storage and uploads. Runs in your browser.
Estimated file size
- File size (MB, decimal)
- 43.2 MB
- File size (MiB, binary)
- 41.2 MiB
- Total bytes
- 43,200,000 bytes
- Duration
- 2,700 s
Assumes constant bitrate (CBR). Variable-bitrate (VBR) files vary around the average; container/metadata overhead adds a small amount.
About this tool
The size of a constant-bitrate audio file is determined entirely by its bitrate and its length: multiply the bitrate (in bits per second) by the duration (in seconds) and divide by eight to get bytes. This calculator does exactly that, letting you pick a common podcast/music bitrate or enter your own and set the duration in hours, minutes, and seconds. It reports the result in both decimal megabytes (MB, base 1000 — how storage and hosts usually quote sizes) and binary mebibytes (MiB, base 1024 — what your operating system often shows), because the two differ by about 5% and the gap confuses people. Podcasters use this to predict episode sizes for hosting limits and listener downloads; producers use it to budget storage. The estimate assumes constant bitrate; variable-bitrate encodes hover around their average, and container and tag overhead add a little. All calculation is local.
How to use it
- Enter the bitrate in kbps, or pick a preset (128 is typical spoken-word; 256–320 is high-quality music).
- Set the duration in hours, minutes, and seconds.
- Read the size in MB and MiB.
- Use it to plan hosting storage and download sizes.
Frequently asked questions
- How is audio file size calculated?
- Size in bytes = bitrate (bits per second) × duration (seconds) ÷ 8. A 128 kbps file is 128,000 bits per second, so one hour is 128,000 × 3,600 ÷ 8 = 57,600,000 bytes ≈ 57.6 MB.
- What bitrate should I use for a podcast?
- Spoken-word podcasts sound clear at 64–128 kbps mono or stereo; 128 kbps is a common default. Music and highly produced shows benefit from 192–320 kbps. Higher bitrate means better quality but a proportionally larger file.
- Why are MB and MiB different?
- MB (megabyte) is 1,000,000 bytes; MiB (mebibyte) is 1,048,576 bytes (1024²). Storage vendors and hosts quote MB, while many operating systems display MiB but label it "MB". The ~4.86% difference is why a file can look slightly different in two places.
- Does this work for variable bitrate (VBR) files?
- It estimates based on a constant bitrate. A VBR file targets an average bitrate, so enter that average for a close estimate; the actual size will vary slightly with the content's complexity.
- Does it include file overhead?
- No. The number is the raw audio data size. Container structure (MP3 frames, MP4 atoms) and metadata such as ID3 tags and cover art add a small, roughly fixed amount on top.
- Is anything uploaded?
- No. Only the bitrate and duration you enter are used, and the calculation runs entirely in your browser.