Free - Online - Windows app available

Audio Bitrate Calculator

Find the bitrate that fits a file size limit, or the file size a bitrate will give you - for MP3, AAC, Opus, Ogg Vorbis, WMA, AC-3 and WAV.

Bitrate from file sizeFile size from bitrateStorage capacityWAV and PCM sizeMP3AAC / M4AOpusRuns in your browserNothing uploaded

Calculate in your browser

Online audio bitrate and file size calculator

Five calculators, one set of tabs - the answer updates as you type.

Nothing is uploaded: the sums run in your browser.

Format

Duration

Tracks

Target file size

Unit

Tag reserve (KB)

Durations can be typed as 3:30, 1:02:45, 45m or 90s. A plain number means minutes. Results cover the audio stream, so tags, cover art and the container add a little. Prefer to work offline? The free Windows app has the same five calculators.

How to use it

From a size limit to the right bitrate in three steps

Pick a calculator

Choose a tab: find a bitrate, find a file size, check storage capacity, size uncompressed audio or browse the reference table.

Enter what you know

Choose the format, type the duration and add your size limit or bitrate. Presets cover common limits, a CD, a DVD and USB sizes.

Use the answer

The result shows the bitrate step your encoder really offers and the file size it gives. Copy it, or copy a link that reopens the same calculation.

Windows desktop app

X Audio Bitrate Calculator for Windows

The online calculator is ideal for a quick answer. The free Windows app does the same sums offline, in its own small window.

All five calculators - bitrate, file size, capacity, uncompressed and reference

Works offline - no internet connection, no account, no ads

Remembers your settings - format, values and the tab you last used

Portable and free - one .exe, no installer

Download for Windows Free - Windows 10/11, 64-bit - portable .exe

About the Windows app - features, shortcuts and checksum →

Five calculators in one place

What the audio bitrate calculator works out

Five audio calculators sit behind one row of tabs.

Each one updates as you type, so there is no Calculate button to press.

Calculator	You enter	You get
Find bitrate	Duration, track count, target size, space to keep for tags and cover art	The highest bitrate step that fits, the size it gives and a quality guide
Find file size	Bitrate and duration	File size, plus size per minute and per hour
Capacity	Storage size, bitrate and average track length	Hours of audio and number of tracks that fit
Uncompressed	Sample rate, bit depth, channels and duration	Exact WAV size and bitrate, with a FLAC estimate
Reference	Format and your own duration	A size table for every bitrate step of that format

Every format has its own bitrate steps. MP3 stops at 320 kbps, Opus at 256 kbps and AC-3 goes up to 640 kbps for surround sound.

If your target needs more than the format allows, the calculator says so instead of showing a setting your encoder does not have.

The maths

How audio file size is calculated

Audio file size is bitrate multiplied by duration.

Bitrate is counted in kilobits per second, where 1 kbps is 1,000 bits per second, and a byte is 8 bits.

file size in bytes = bitrate in kbps x 1000 x seconds / 8
bitrate in kbps    = file size in bytes x 8 / seconds / 1000

Example: a 3 minute 30 second song at 192 kbps is 192 x 1000 x 210 / 8 = 5,040,000 bytes. Windows shows that as 4.81 MB.

The other way round: to fit the same song into 5 MB you could use up to 199.7 kbps. The nearest MP3 step that fits is 192 kbps.

Bitrate	Per minute	Per hour	3:30 song
64 kbps	0.46 MB	27.5 MB	1.60 MB
96 kbps	0.69 MB	41.2 MB	2.40 MB
128 kbps	0.92 MB	54.9 MB	3.20 MB
192 kbps	1.37 MB	82.4 MB	4.81 MB
256 kbps	1.83 MB	109.9 MB	6.41 MB
320 kbps	2.29 MB	137.3 MB	8.01 MB
1,411 kbps (CD-quality WAV)	10.09 MB	605.6 MB	35.33 MB

These sizes use 1 MB = 1024 KB. They cover the audio itself, so tags, cover art and the file container add a little on top.

Choosing a bitrate

Which audio bitrate should you use?

The right bitrate depends on the format, because newer formats need less data for the same sound.

The table below is a rule of thumb, not a listening test. Your ears, your headphones and the music itself all matter.

Format	Speech and podcasts	Everyday music	High quality
MP3	64 to 96 kbps	128 to 192 kbps	256 to 320 kbps
AAC / M4A	48 to 64 kbps	96 to 160 kbps	192 to 256 kbps
Opus	24 to 32 kbps	64 to 96 kbps	128 to 160 kbps
Ogg Vorbis	48 to 64 kbps	96 to 160 kbps	192 to 256 kbps

Working to a size limit? Start from the limit, let the calculator pick the bitrate and then check it against this table.

If the result lands in the speech column for a music file, switch to a more efficient format such as Opus or AAC before you lower the quality further.

FAQ

Audio bitrate and file size - frequently asked questions

How do I calculate audio file size from bitrate?

Multiply the bitrate in kbps by 1,000 and by the duration in seconds, then divide by 8 to get bytes. A 3 minute 30 second track at 192 kbps is 192 x 1000 x 210 / 8 = 5,040,000 bytes, which Windows shows as 4.81 MB.

What bitrate do I need to fit audio into a file size limit?

Multiply the size limit in bytes by 8, divide by the duration in seconds and divide by 1,000. Then round down to a bitrate your format offers. For a 5 MB limit and a 3:30 track the exact answer is 199.7 kbps, so 192 kbps is the MP3 setting to use.

How many MB per minute is 128 kbps?

About 0.92 MB per minute, or 54.9 MB per hour. 192 kbps is about 1.37 MB per minute and 320 kbps about 2.29 MB per minute.

Why is my real file a little bigger than the calculated size?

The calculation covers the audio stream only. Tags, embedded cover art and the file container add to it, and cover art alone can be several hundred KB. The Find bitrate calculator lets you reserve space for tags and cover art so the result still fits your limit.

Does this work for VBR files?

Yes, as an estimate. A variable bitrate encode aims at an average, so the file lands near the calculated size instead of exactly on it. Constant bitrate files match the calculation closely.

Can it calculate FLAC or WAV file sizes?

WAV yes, exactly: the Uncompressed tab works it out from sample rate, bit depth and channels. FLAC depends on the music, so the calculator shows an estimate of 50 to 70 percent of the WAV size.

Why do some calculators give a different MB figure?

There are two definitions of a megabyte. Windows counts 1 MB as 1024 KB, while storage makers and many websites count 1 MB as 1000 KB. Click the Units line under the result to switch between the two.

How many songs fit on a USB stick?

A 32 GB stick holds about 370 hours of audio at 192 kbps, which is roughly 6,300 songs of 3 minutes 30 seconds. The Capacity tab works this out for any storage size, bitrate and track length.

Can I share or save a calculation?

Yes. Click "Copy link to this calculation" and paste the link anywhere. Opening it brings back the same tab and values, and nothing is stored on our server.

Is there an offline version?

Yes. X Audio Bitrate Calculator for Windows is a free portable program with the same five calculators. It runs on Windows 10 and 11 and needs no internet connection.