Audio File Size Calculator
Estimate how many megabytes an episode will take from its bitrate or WAV settings and run time — for MP3 and uncompressed WAV — before you export and upload.
Know the size before you upload
File size decides how long an episode takes to upload, how much of your hosting storage and bandwidth it uses, and how quickly listeners download it on a phone. A compressed MP3 is sized entirely by its bitrate and length; an uncompressed WAV is sized by its sample rate, bit depth, and channel count. Seeing both lets you record and edit at full quality, then pick a sensible publishing bitrate.
Working out an export setting? Check the raw data rate with the Audio Bitrate Calculator, or plan the length first with the Podcast Episode Length Estimator.
Frequently Asked Questions
How is MP3 file size calculated?
For a constant-bitrate MP3 the size depends only on the bitrate and the length: bytes = bitrate in kilobits per second × 1000 ÷ 8 × the number of seconds. So a 128 kbps file runs about 57.6 MB an hour, and 64 kbps about half that. A variable-bitrate export and the small ID3/container overhead shift the real file a little, which is why the tool calls it an estimate.
Why is a WAV file so much larger than an MP3?
WAV is uncompressed PCM, so it stores every sample in full: size = sample rate × bit depth in bytes × channels × seconds. CD-quality stereo (44.1 kHz, 16-bit, 2 channels) is about 10.6 MB per minute, or roughly 635 MB an hour — around eighty times a 128 kbps MP3 of the same length. That is why you record and edit in WAV but publish a compressed file.
What bitrate should I publish a podcast at?
Spoken-word mono podcasts are commonly exported at 64–96 kbps, and stereo or music-heavy shows at 128 kbps or more. Higher bitrates sound better but make bigger files and slower downloads. Enter a couple of options here to see the size trade-off before you commit, and check any maximum-file-size limit your host sets.
Do MB here mean 1,000,000 or 1,048,576 bytes?
This calculator uses the decimal convention, 1 MB = 1,000,000 bytes, because that is how podcast hosts and download reports usually quote file sizes. Some software reports mebibytes (1 MiB = 1,048,576 bytes) instead, so a file may look about 5% smaller there for the same number of bytes.
Estimates only. Variable-bitrate encoding and container overhead change the exact file size. Confirm any maximum-upload limit with your podcast host. Not professional engineering advice.