Podcast File Size Calculator

About this calculator

This calculator converts a bitrate and duration into a file size using size (MB) = bitrate (kbps) × duration (seconds) / 8 / 1000, dividing by 8 to turn bits into bytes and by 1000 to turn kilobytes into megabytes — the same math that applies to any constant-bitrate audio encoding, whether MP3, AAC or Opus.

Podcast producers use it to predict how large a finished episode will be before exporting, so they can choose a bitrate — commonly 128 or 192 kbps for spoken-word content — that balances audio quality against hosting storage limits and listener download size on mobile data. Audio editors also use it in reverse, working out what bitrate keeps a long-form episode under a hosting platform's file size cap.