Calculate audio file size, bitrate or duration
This audio file size calculator answers the three questions that come up whenever audio has to fit somewhere. How big will a recording be at a given bitrate and length? What bitrate do I need to squeeze it under an upload or email limit? And how many hours fit in a given amount of storage? Pick MP3, AAC, Opus, Ogg Vorbis, uncompressed WAV or FLAC, enter what you know, and the result updates as you type.
Under the result, a comparison table shows the same length in ten common formats, from 64 kbps Opus to 24-bit/96 kHz WAV, with the storage each needs per hour. To check a real file, drop it on Read from a file: its length and size are read in your browser and turned into the actual average bitrate, tags and cover art included.
How to use the Audio File Size Calculator
- Choose what to calculate: File size, Bitrate or Duration.
- Pick the Format. For MP3, AAC, Opus, Vorbis or Other, type the bitrate or tap a common value; for WAV and FLAC choose the sample rate, bit depth and channels.
- Enter the length in hours, minutes and seconds, and/or the file size in KB, MB, GB, MiB or GiB.
- Read the result, the per-minute and per-hour figures, and the comparison table.
- Optionally drop an audio file on Read from a file to fill everything in from a real recording.
Audio File Size Calculator features
Three calculations in one
Size from bitrate and length, the bitrate that fits a size, or the length that fits a size.
Uncompressed audio done right
WAV and AIFF are sample rate × bit depth × channels, from 8 kHz mono up to 192 kHz 7.1 surround.
FLAC as a labelled estimate
FLAC size depends on the music, so you choose a share of the WAV size (58 % by default) rather than getting a false-precise number.
Comparison table
The same length in ten formats side by side, plus storage per hour.
Real files
Reads the duration of MP3, M4A, Opus, Ogg, WAV and FLAC files in your browser and shows their true average bitrate.
The formulas
Size (bytes) = bitrate (bits per second) × duration (seconds) ÷ 8. Audio bitrates are quoted in kilobits per second, where 1 kbps = 1,000 bits per second. Example: a 4-minute song at 192 kbps is 192,000 × 240 ÷ 8 = 5,760,000 bytes, which is 5.76 MB or 5.49 MiB.
For uncompressed PCM the bitrate is sample rate × bit depth × channels. CD audio is 44,100 × 16 × 2 = 1,411,200 bits per second: 10.58 MB per minute and 635 MB per hour, which is why a 74-minute audio CD holds about 783 MB. Turn the formula around for the other two modes: bitrate = size × 8 ÷ duration, and duration = size × 8 ÷ bitrate.
Storage per hour for common formats
| Format | Bitrate | Per hour |
|---|---|---|
| Opus (speech, podcasts, music) | 64 kbps | 28.8 MB |
| MP3 | 128 kbps | 57.6 MB |
| Ogg Vorbis | 160 kbps | 72 MB |
| AAC / M4A | 256 kbps | 115.2 MB |
| MP3 | 320 kbps | 144 MB |
| FLAC, 16-bit 44.1 kHz stereo | ≈ 700–1,000 kbps | ≈ 320–445 MB (estimate) |
| WAV, 16-bit 44.1 kHz stereo | 1,411.2 kbps | 635 MB |
| WAV, 24-bit 48 kHz stereo | 2,304 kbps | 1.04 GB |
| WAV, 24-bit 96 kHz stereo | 4,608 kbps | 2.07 GB |
Why real files differ a little
Once you know the bitrate you need, the MP3 compressor and AAC compressor can hit a target size directly, the WAV compressor shrinks uncompressed recordings, and for video the video bitrate calculator does the same sums with a picture.
- Tags and cover art sit on top of the audio: a 500 KB cover adds 500 KB to every song that carries it.
- Variable bitrate (VBR) files only average their nominal bitrate, so quiet or simple passages make them smaller and dense ones larger.
- Containers add a little: MP4 indexes, Ogg pages and WAV headers usually cost well under 1 % of the file.
- MB or MiB? Drive makers, phones and most upload forms count 1 MB = 1,000,000 bytes, while some operating systems show sizes in 1,048,576-byte units under the same name.
Audio File Size Calculator FAQ
How do I calculate audio file size?
Multiply the bitrate in bits per second by the length in seconds and divide by 8 to get bytes. A 3-minute MP3 at 128 kbps is 128,000 × 180 ÷ 8 = 2,880,000 bytes, or 2.88 MB.
How big is a WAV file per minute?
At CD quality (44.1 kHz, 16-bit, stereo) a WAV takes 10.58 MB per minute. 24-bit at 48 kHz takes 17.28 MB per minute, and mono halves either figure.
How many songs fit in 1 GB?
About 297 songs of 3½ minutes at 128 kbps (3.36 MB each), about 119 at 320 kbps, and about 27 as CD-quality WAV.
What bitrate do I need to fit a file under a size limit?
Choose Bitrate, enter the size limit and the length, and the calculator shows the maximum average bitrate, plus the highest standard MP3 bitrate that fits. Leave a little headroom for tags and cover art.
How accurate is the FLAC estimate?
It is only a guide. FLAC is lossless, so the size depends on how predictable the audio is: music usually ends up around 50–70 % of the WAV, quiet speech lower, noisy recordings higher. Adjust the share with the slider.
Is my file uploaded when I use Read from a file?
No. The browser reads the file’s length and size locally; nothing leaves your device.