Audio File Size Calculator

About This Tool

The Audio File Size Calculator estimates how much storage space an audio recording will consume across different file formats. By entering the duration, sample rate, bit depth, and number of channels, you get instant size estimates for uncompressed WAV, lossless FLAC, and lossy MP3 at three common bitrates. This is essential for planning recording sessions, managing storage for music libraries, and choosing the right format for distribution.

Understanding Uncompressed Audio (WAV/AIFF)

WAV and AIFF files store raw PCM (Pulse Code Modulation) audio data without any compression. The file size is entirely determined by four factors: sample rate (how many samples per second), bit depth (how many bits per sample), channel count (mono, stereo, surround), and duration. The formula is straightforward: size in bytes = sample rate × (bit depth / 8) × channels × duration in seconds. Uncompressed formats preserve every detail of the recording and are the standard working format in professional studios.

Sample Rate Explained

Sample rate defines how many times per second the audio waveform is measured. The Nyquist theorem states that you need at least twice the highest frequency you want to capture. Since human hearing tops out around 20 kHz, a 44.1 kHz sample rate captures the full audible spectrum. Higher sample rates (96 kHz, 192 kHz) capture ultrasonic frequencies and may provide benefits during processing (better filter behavior, less aliasing) even though the extra frequencies themselves are inaudible. The trade-off is proportionally larger file sizes.

Bit Depth and Dynamic Range

Bit depth determines the number of possible amplitude values for each sample and directly affects dynamic range. 16-bit audio provides 96 dB of dynamic range (sufficient for playback), 24-bit provides 144 dB (far exceeding any real-world recording environment), and 32-bit float provides essentially unlimited headroom for mixing. Recording at 24-bit is standard practice because it provides a comfortable noise floor margin during tracking, even though the final product may be dithered down to 16-bit for distribution.

Lossy Compression (MP3, AAC, OGG)

Lossy codecs like MP3 use psychoacoustic models to discard audio information that is theoretically less perceptible to human hearing. The bitrate (measured in kilobits per second) controls how aggressively data is discarded. At 128 kbps, MP3 is acceptable for casual listening. At 192 kbps, most listeners cannot distinguish it from the original in a blind test. At 320 kbps, the difference is virtually imperceptible even on high-end equipment. MP3 file size depends only on bitrate and duration, not on the original recording parameters.

Lossless Compression (FLAC, ALAC)

Lossless codecs compress audio without discarding any data. The decoded output is bit-for-bit identical to the original. FLAC typically achieves 40-60% of the original WAV size depending on the audio content (simple, quiet passages compress better; dense, noisy passages compress less). FLAC is ideal for archiving master recordings, distributing high-fidelity music, and as a space-efficient working format when WAV is too large but quality must be perfect.

Choosing the Right Format

For recording and editing, use WAV or AIFF at the highest sample rate and bit depth your system supports. For archiving, use FLAC to save space without quality loss. For streaming and portable devices, MP3 or AAC at 256-320 kbps offers the best balance of quality and size. For podcasts and voice content, 128 kbps MP3 is usually sufficient since voice has a narrower frequency range than music. Always keep your master files in an uncompressed or lossless format and generate lossy versions as needed for distribution.