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Free Online Audio File Size and Recording Time Calculator

Calculate audio file size, recording time or the bitrate you need, free and without any file at all. Uncompressed sizes are exact arithmetic rather than estimates, compressed ones are worked out from the bitrate, and the page says plainly which of the figures are approximate and exactly why that is.

Free Forever No File Needed Exact For WAV Nothing To Download

Free Online Audio File Size and Recording Time Calculator

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What do you want to know

The numbers

Format

Bitrate, in kbps 32 for speech, 128 for ordinary music, 320 for the most MP3 allows.

Length

The answer

Per minute-

Per hour-

Data rate-

Exact or approximate-

An hour of audio, at a glance

Setting	Per minute	Per hour	Typical use

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How to Work Out an Audio File Size

Fill in two of the three and the third appears.

Pick the question you are asking How big a file will be, how long will fit in a space, or what bitrate is needed to fit a length into a size.

Choose the format The controls change with it: compressed formats want a bitrate, uncompressed ones want a sample rate, channels and bit depth.

Fill in what you know The answer updates as you type. There is no button to press.

Check the table underneath Common settings with their size per minute and per hour, which is often faster than calculating anything.

Where the Arithmetic Is Exact and Where It Is Not

WAV is certain. The rest are close.

WAV is exact arithmetic, the compressed formats are not. An uncompressed file is the sample rate multiplied by the channels, the bit depth and the length, plus a small header, and that is precisely what you get. MP3 and AAC at a fixed bitrate come very close. Variable bitrate and FLAC depend on the sound itself, so those figures are estimates and are labelled as such.

Tags and artwork add to the real file. An embedded cover image is often a few hundred kilobytes and is not part of this calculation. If you are fighting a hard limit, leave a little room for it, or strip the artwork with the metadata remover.

FLAC is roughly half of WAV, and "roughly" is the honest word. Being lossless, its size depends entirely on how compressible the sound is. Quiet speech can come down to a third; dense loud music barely compresses at all. The figure here uses a typical ratio.

Nothing is uploaded, and that is checkable. Turn your wifi off after the page has loaded and every one of these tools still works, which would be impossible if a server were doing the job.

The work happens on your own machine. Your file is opened by this page, not sent anywhere. That is why there is no upload bar, no queue and no waiting for a server. It is also why a long recording leans on your own memory: nothing is being done for you somewhere else.

Key Features & Capabilities

What this tool does, and what it deliberately does not.

Three questions, one page Size from length, length from space, or the bitrate needed to fit a length into a size.

Exact where it can be Uncompressed sizes are arithmetic, not estimates, and the page says which figures are which.

Real limits as presets Messaging, email, a CD and a memory card, so you do not have to remember the numbers.

A reference table Common settings per minute and per hour, which answers most questions without any typing.

Nothing to download No file goes in or out. It is arithmetic, and it runs instantly.

Nothing uploaded There is nothing to upload, because you never give it a file.

About the Audio File Size Calculator

Every question about audio file size comes down to one relationship: bytes equals bitrate times seconds divided by eight. Rearranged, that same equation answers all three of the questions people actually ask. Given a length and a quality, how big will it be. Given a space, how long will fit. Given a length and a space, what quality is needed. They are not three different calculations, which is why they are on one page rather than three.

Compressed formats make that relationship easy, because the bitrate is a number you chose. An MP3 at 128 kilobits per second really does produce about 128 kilobits for every second, give or take the tags. Variable bitrate encoders aim for an average rather than holding a fixed rate, so the result lands close to the figure but not exactly on it.

Uncompressed audio works differently and is the only case where the answer is genuinely exact. A WAV file is the sample rate multiplied by the number of channels, multiplied by the bytes per sample, multiplied by the length, plus a forty four byte header. Nothing is estimated. That is why CD quality stereo comes to almost exactly ten megabytes per minute, a number worth remembering.

FLAC sits in between and is the one place a calculator has to be honest about uncertainty. Being lossless, its size depends on how compressible the material is. Quiet spoken word can come down to a third of the WAV size; dense, loud, heavily limited music sometimes barely compresses at all. Around half is typical, and that is what is used here, labelled as an estimate rather than presented as a fact.

The one thing that regularly surprises people is artwork. An embedded cover image is often two or three hundred kilobytes, occasionally more, and none of it is audio. On a three minute track that can be five per cent of the file. If you are fighting a hard limit such as a messaging app's, the artwork is usually the easiest thing to remove, and the metadata remover on this site will take it out without touching the sound.

Frequently Asked Questions

Sizes, lengths, bitrates and recording time.

It depends entirely on the format. An hour of MP3 at 128 kbps is about 55 megabytes. At 320 kbps it is about 137. An hour of CD quality WAV is about 605 megabytes, and the same hour as FLAC is usually around 350. The table on this page lists the common cases.

Choose the second option and pick the 32 GB preset. At CD quality WAV it is around 54 hours; at 128 kbps MP3 it is around 580 hours. Whether your recorder can produce a single file that long is a separate question.

Choose the third option, set the length to an hour and the space to 16 megabytes, and the answer appears: about 35 kbps. That is fine for speech in mono and useless for music, which the page will also tell you.

Usually artwork. An embedded cover image is frequently a few hundred kilobytes and is not part of this calculation, which covers the audio only. Tags add a little as well. If you are up against a hard limit, strip the artwork with the metadata remover.

Yes, to within the forty four byte header. An uncompressed file is the sample rate times the channels times the bit depth in bytes times the length, with no approximation anywhere. The compressed formats at a fixed bitrate are very close; variable bitrate and FLAC genuinely depend on the sound, so those are labelled as estimates.

No, and there is nowhere to put one. This page is arithmetic about a file that may not exist yet, which is usually the point: you want to know before you record or export.