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How big is an audio recording per minute on a Mac?

Tested on macOS 26.4.1 (Tahoe), Apple M3 Max, 3 Sept 2026. Updated 2026-09-03.

One minute of stereo 24-bit 48 kHz audio is 16.5 MB on disk, one minute of 16-bit 48 kHz WAV is 11.0 MB, and one minute of 320 kbps MP3 is 2.4 MB. Those figures are measured from 45 real recordings on the author's Mac, not calculated from a spec sheet. One hour of 24-bit 48 kHz audio is 0.97 GB; one hour of MP3 is 0.14 GB.

How many MB is one minute of audio?

The table below comes from 45 recordings made with AirCheck on the author's Mac, measured in Finder after the take stopped. All are stereo. The numbers are what you will see on disk, including file headers.

The arithmetic behind the PCM rows is simple. Bytes per second = sample rate x (bit depth / 8) x channels. For 24-bit 48 kHz stereo that is 48,000 x 3 x 2 = 288,000 bytes per second, or 17.28 million bytes per minute, which Finder reports as roughly 16.5 MB. The MP3 row is fixed by its bitrate: 320,000 bits per second / 8 = 40,000 bytes per second = 2.4 MB per minute. A mono file is exactly half of the PCM figures. See 16-bit vs 24-bit for why the bit depth changes the size by 50 percent.

How many hours of audio fit in 1 GB, 10 GB or 100 GB?

Hours per GB is 1 divided by GB per hour. For 24-bit 48 kHz: 1 / 0.97 = 1.03 hours per GB. The same division gives the rest.

In practice this means a 256 GB MacBook with 50 GB free can hold about 51 hours of 24-bit 48 kHz recordings or about 357 hours of 320 kbps MP3. Disk space is the only ceiling in the recording app itself, and the WAV container limit discussed below is about 4 hours at 24-bit 48 kHz. For planning a single very long session, see how long you can record audio on a Mac.

How big is a 30, 60, 90 or 120 minute recording?

Multiply the MB per minute figure by the duration. Rounded to whole MB:

A real check: the longest continuous take in the author's library is 7,550 seconds (2 h 5 min) at 24-bit 48 kHz and weighs 2.07 GB. 125.8 minutes x 16.5 MB = 2,076 MB, so the table predicts real files to within a percent. A 90-minute lecture captured as 16-bit WAV is under 1 GB; the same lecture as MP3 320 is about 216 MB, small enough to email through most services that cap attachments at a few hundred MB. A two-hour DJ set as 24-bit 48 kHz is just under 2 GB.

Is there a maximum size for a WAV file?

Yes. The WAV container stores its size in a 32-bit field, so a standard WAV cannot exceed 4 GiB (Wikipedia, WAV). At 16.5 MB per minute that is 4,096 / 16.5 = about 248 minutes, or 4 h 8 min, of 24-bit 48 kHz audio. At 16-bit 48 kHz it is 4,096 / 11.0 = about 372 minutes, or 6 h 12 min. Apple's afconvert lists two extended variants for longer files, shown in its own format list as 'RF64' = WAVE (RF64 for length over 4 GB) and 'BW64'; not every app opens those. MP3 has no such ceiling in practice: a 4 GiB MP3 at 320 kbps would be about 28 hours long.

If a session may run past four hours at 24-bit, split it into takes or record 16-bit. For the format decision itself, see WAV vs AIFF vs MP3.

Measured size per format (stereo, 45 real recordings)

FormatMB per minuteGB per hourHours per 10 GB2-hour take (GB)Minutes until the 4 GiB WAV limit
16-bit 44.1 kHz WAV10.10.5916.91.21405
16-bit 48 kHz WAV11.00.6415.61.32372
24-bit 44.1 kHz WAV/AIFF15.10.8911.21.81271
24-bit 48 kHz WAV/AIFF16.50.9710.31.98248
MP3 320 kbps2.40.14710.291,706

MB per minute and GB per hour are measured in Finder; the other columns are derived by multiplication or division from those two.

Where AirCheck fits

AirCheck ($39 one-off, macOS 14 or newer) shows the size of every take next to its duration in the in-app Library, and lets you pick the export format before you press record: WAV 16-bit, WAV 24-bit or MP3 320 kbps. The recording itself is always a 24-bit AIFF master that is converted once when the take stops, so the numbers in the table are exactly what lands in ~/Music/AirCheck. That makes disk planning for a 2-hour set or a semester of lectures a multiplication, not a guess.

When you do not need it: If you only need the arithmetic, you do not need any app: Finder's Get Info on an existing file gives you MB, and the table above gives you the rate. QuickTime Player's audio recording is free if a microphone-only .m4a is enough.

AirCheck records what your Mac plays, or any input, to one file. $39 once.

Buy AirCheck for $39

macOS 14 or newer. One-off payment. Fourteen-day refund, no questions asked.

Questions people ask

How many GB is 1 hour of audio?

0.97 GB at 24-bit 48 kHz, 0.64 GB at 16-bit 48 kHz, and 0.14 GB (144 MB) as 320 kbps MP3, measured on real files. A 44.1 kHz file is about 9 percent smaller than the same bit depth at 48 kHz.

How big is a 2 hour WAV file?

About 1.98 GB at 24-bit 48 kHz and 1.32 GB at 16-bit 48 kHz. The author's longest real take, 2 h 5 min at 24-bit 48 kHz, is 2.07 GB, which matches the per-minute figure within one percent.

Does 24-bit double the file size?

No. It adds 50 percent: 16.5 MB per minute versus 11.0 MB at 48 kHz. Three bytes per sample instead of two is a 3:2 ratio, and the measured files follow that ratio exactly.

How big is an MP3 per minute?

2.4 MB per minute at 320 kbps, regardless of sample rate. Lower bitrates scale down proportionally: 128 kbps is 0.96 MB per minute by the same bitrate / 8 x 60 arithmetic.

Sources

Hannes Hennerbichler builds AirCheck and records his own DJ sets with it through a Focusrite Scarlett 8i6. Every step on this page was run on the macOS version stated above. Drafted with AI assistance, checked and edited by the author. About