How to use this calculator
Use File size to plan a podcast export, music file or recording session. For uncompressed WAV or AIFF, enter sample rate in Hz, stored bits per sample and channels. For compressed audio, enter the average bitrate across all channels. Use Bitrate with a size limit and duration to find the average bitrate budget, or Recording time with available storage and a known audio format. The Video tab retains separate video and audio bitrate estimates.
The math behind it
PCM bitrate (kbps) = sample rate × storage bits per sample × channels ÷ 1,000 Audio bytes = bitrate (kbps) × 1,000 × seconds ÷ 8 Average bitrate (kbps) = bytes × 8 ÷ seconds ÷ 1,000 Recording seconds = bytes × 8 ÷ (bitrate kbps × 1,000) Video MB = (video Mbps + audio kbps ÷ 1,000) × seconds ÷ 8
A worked example
Three minutes of 44,100 Hz, 16-bit stereo PCM is 1,411.2 kbps and 31.752 MB (about 30.28 MiB) before headers. At an average 128 kbps, the same duration uses 2.88 MB. A 2.88 MB audio budget over 180 seconds permits an average 128 kbps; at that rate, 2.88 MB holds 3 minutes. For video, 60 seconds at 8 Mbps plus 128 kbps audio uses 60.96 MB.
Assumptions & precision
Estimates cover media data, excluding file headers, tags, artwork and container overhead. MB/GB are decimal; MiB/GiB are binary. kbps means 1,000 bits per second. PCM uses stored bits per sample (for example, 24-bit samples stored in 32-bit slots require 32 bits). Supported PCM inputs are whole-number sample rates from 1 to 768,000 Hz, 8/16/24/32/64 stored bits and 1–32 channels. No fixed compression ratio is assumed for FLAC or other compressed formats; enter a known or estimated average bitrate. A bitrate budget is a mathematical limit, not a guarantee that a codec can achieve a particular quality. Size and storage may be zero; bitrate must be positive when estimating size or time, and duration must be positive when solving for bitrate. Results retain unrounded intermediate values and display up to 6 decimals; recording time rounds to a second. Values above 10¹⁵ are rejected. Leave space for overhead.
Common questions
How do I calculate audio bitrate from sample rate?
For uncompressed PCM, multiply sample rate by storage bit depth and channel count. Divide by 1,000 for kbps. At 44,100 Hz × 16 bits × 2 channels, the rate is 1,411.2 kbps. Choose File size to see this rate alongside the size estimate.
Can sample rate and bit depth predict MP3 or FLAC size?
Not by themselves. MP3, AAC and Opus depend on encoder settings; FLAC is lossless but its compression varies with the source audio. Use Compressed audio and enter an average bitrate. Variable-bitrate files may differ from the estimate.
Does a higher bitrate always mean better audio quality?
No. Codec, encoder settings, source quality and listening conditions matter. This tool estimates storage and data rate; it does not measure sound quality or restore detail lost from a recording.
Why are MB and MiB different?
One MB is 1,000,000 bytes; one MiB is 1,048,576 bytes. The same audio data therefore has a smaller numeric size in MiB. Match the unit used by your storage or upload limit.
Where is the video file size calculator?
Choose the Video tab above. It calculates file size from video and audio bitrate, or the video bitrate budget remaining after audio is subtracted. A size limit too small for the audio alone is rejected.