Audio File Size Calculator
Minutes times kilobits — the CD master, the MP3 discount, and the sample-rate law underneath.
Audio File Size Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Constant-bitrate lanes — VBR encodes wobble
- FLAC's 60–75% is doctrine, not computed
In short: Four minutes of CD-quality PCM — 1,411.2 kbps, derived as 44,100 samples × 16 bits × 2 channels — is 42.336000 MB, running 10.584000 MB every minute. The same four minutes as a 320 kbps MP3 is 9.600000 MB, and at 128 kbps just 3.840000: the lossy discount is the psychoacoustic model deciding what you will not miss. Decimal units throughout — the calculator world's 7.03 MB for a three-minute 320 track is the same number dividing by 1,024 twice.
Formula
MB = kbps × seconds ÷ 8,000 ··· CD PCM = 44,100 × 16 × 2 ÷ 1,000 = 1,411.2 kbps
Uncompressed audio is a sample count: 44,100 samples a second, 16 bits each, two channels — 1,411.2 kilobits a second, 10.584000 MB a minute, which is the number every lossy format is measured against. MP3 and AAC keep a running estimate of what the ear will not miss and spend 320 or 128 kbps instead; FLAC keeps everything and spends about 60–75% of PCM depending on the music's predictability. One trap is worth naming: many calculators divide bytes by 1,024 twice and print 7.03 MB for a three-minute 320 kbps track — that figure is mebibytes, not megabytes; decimal honesty reads 7.200000.
Worked Example
- Enter the duration in minutes.
- Pick the bitrate lane.
- Read the size and the per-minute rate.
- Compare the lossy discount honestly.
Defaults: 4 min at 1,411.2 kbps → 42.336000 MB, 10.584000/min, the 320 kbps MP3 at 9.600000. Drive the minutes to 90 (a set, an audiobook hour-and-a-half) at CD rate → 952.560000 MB: the lossless habit, priced.
Strengths & Limits Of This Model
Where this engine is strong
- The PCM derivation shown, not asserted
- The MiB trap named beside the decimal read
Where it stops
- No channel or sample-rate inputs — the chips carry the lanes
Practical Use Cases
Set budgets
a live set on the recorder
Audiobook planning
hours against the shelf
Archive ripping
the whole shelf as FLAC
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Audio File Size Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How do I calculate audio file size?
Bitrate times duration: kilobits per second times seconds, divided by 8,000, lands in megabytes. Four minutes at 320 kbps is 9.600000 MB; the same track as CD-rate PCM is 42.336000 MB. One multiplication, honest units.
Why is CD quality 1,411.2 kbps?
It is the sample rate made arithmetic: 44,100 samples per second, 16 bits each, stereo's two channels — 44,100 × 16 × 2 = 1,411,200 bits per second. Every lossy format is a discount against that derived number.
Why do some calculators say 7.03 MB for a 3-minute MP3?
They are dividing bytes by 1,024 twice and printing mebibytes under a megabyte label. The decimal read is 7.200000 MB for 320 kbps over 180 seconds. Both numbers describe the same file; this page keeps one ruler and names it.
Is 320 kbps MP3 good enough?
For most listeners on most gear, transparent — blind tests rarely separate it from lossless at the same master. The honest answer is budgetary: 320 kbps spends 9.600000 MB on four minutes against 42.336000, and only your ears and your shelf can arbitrate.
How big is a FLAC file?
FLAC is lossless and variable — it spends about 60–75% of the PCM rate depending on how predictable the music is, so a CD-length album lands near 250–300 MB against 441.000000 raw. The per-track card here prices PCM; FLAC's discount rides on top.
How many songs fit on a gigabyte?
At the 320 kbps lane, about 2.3 four-minute tracks per hundred megabytes — call it 23 per GB; at the CD rate, five per GB. The division is the whole answer and the chips are the denominators.
What does 24-bit/48 kHz change?
The sample arithmetic: 48,000 × 24 × 2 is 2,304 kbps — 17.280000 MB a minute, the studio chip here. It buys editing headroom, not audible magic; the delivery ladder still ends in 320 or 128.
Do streaming counts differ from file sizes?
Same bitrate, different ledger — a stream spends its kilobits on the meter, not the shelf. An hour of 96 kbps streaming is about 43.200000 MB, which is why the music lane looks free beside video; the Data Usage page carries that lane.