How much space will a WAV recording need? A PCM storage worksheet

Laptop, headphones, audio interface and external drive beside a blank notebook. — Original AI-generated editorial photograph-style illustration of a recording desk. No recording, storage benchmark or hardware test is depicted.

A recording plan needs a storage estimate before it needs a bigger drive. For uncompressed PCM audio, you can calculate the audio payload from four values: sample rate, stored bits per sample, channel count and duration. You do not need to record an entire interview to discover its approximate size.

This worksheet is for planning a Mac recording session or an audio handoff. Its numbers are arithmetic examples, not measurements of a recorder, drive or upload service. Start with the format your project actually requires, then work out the space.

Check the encoding before using the formula

A .wav extension identifies a container, not a guarantee of one encoding. The Library of Congress WAVE reference describes a wrapper that can contain different audio encodings and metadata chunks. Its separate LPCM reference explains the regularly sampled, linearly quantised audio this worksheet concerns.

Use the formula for uncompressed, byte-aligned PCM with a known stored sample width. Do not apply it to AAC, MP3 or FLAC as though those formats store the same number of bytes. A compressed file's duration and sample rate alone do not establish its size.

Calculate the audio payload

Audio bytes = sample rate in Hz × stored bits per sample ÷ 8 × channels × seconds.

Microsoft's WAVEFORMATEX documentation defines PCM byte rate using sample rate and block alignment. For extensible formats, the stored container width can differ from the valid audio bit depth. Check the stored width rather than substituting a quality label.

For a hypothetical ten-minute, 48 kHz, 24-bit stereo recording with three stored bytes per channel sample: 48,000 × 3 × 2 × 600 = 172,800,000 audio bytes. That is 172.8 decimal MB, or approximately 164.8 MiB. The two units describe the same payload using different divisors.

Use this reference table

Uncompressed PCM example	Audio MB per minute	Audio MB per hour
44.1 kHz, 16-bit, stereo	10.584	635.04
48 kHz, 16-bit, mono	5.76	345.6
48 kHz, 24-bit, mono	8.64	518.4
48 kHz, 24-bit, stereo	17.28	1,036.8
96 kHz, 24-bit, stereo	34.56	2,073.6

Here, MB means 1,000,000 bytes. Every row assumes packed samples of the stated stored width. Headers, metadata, other project files and spare working capacity are excluded. These settings are examples, not a recommendation to change a project's sample rate or bit depth.

Download the PCM reference table as CSV to use in a spreadsheet. The CSV includes the assumptions and raw byte counts so another person can check the arithmetic.

An external drive beside a blank calculation sheet and headphones on a desk. — Original AI-generated editorial photograph-style illustration of storage planning. The props are illustrative; no drive capacity, recording or transfer was tested.

Budget for the session you will actually keep

Suppose four mono tracks each run for one hour at 48 kHz and 24 stored bits. Their combined audio payload is 4 × 518.4 MB = 2,073.6 MB. A separately retained second copy adds that amount again. Additional takes, exports and a video recording are separate items in the plan.

Use a small inventory rather than one unexplained total:

Each recording stream: duration, channel count and stored PCM width.
Retained takes: which versions you intend to keep.
Deliverables: listening files, project assets and video, estimated separately.
Copies: where the working copy and a separate backup will live.
Available space: the actual free space on each destination, with room for the app's working files.

Silence does not reduce the payload in this uncompressed calculation. A second channel doubles it even if the content in that channel is unhelpful. That is a reason to inspect the intended recording configuration, not to discard channels from an existing master.

Check a small saved sample before relying on the estimate

Save a short sample using your intended recorder and settings, then inspect its encoding, duration and actual file size. A mismatch is a prompt to check units, channel count, stored width and encoding. Do not assume the drive or microphone is faulty because an estimate omitted the container or used a different format.

Keep the original sample and settings note while investigating. If you are choosing QuickTime capture settings, use the voice-note quality guide. If an editor needs the session media rather than a listening file, use the Logic project handoff checklist.

Before recording: write the expected payload, the extra files and the separate copies into your session plan. Check free space against that plan rather than treating the table as a promise that a session will fit.