Audio File Size Calculator

Estimate how large an exported audio file will be based on duration and bitrate — or drop in a real file to see its actual numbers.

How to use the Audio File Size Calculator

  1. Enter your valuesEnter the duration in minutes and seconds (or load a file) and choose a format preset — MP3 64–320 kbps, AAC, Opus, WAV, FLAC — or a custom bitrate.
  2. Read the results instantlyThe estimated size appears in KB/MB/GB with the per-minute and per-hour sizes.
  3. Copy or sharePress the copy icon on any result card, or use Copy link to these values — the page URL stores your inputs so you can bookmark or send the exact calculation.

About the Audio File Size Calculator

The Audio File Size Calculator estimates how large an audio file will be before you record or export it — for MP3, AAC, Opus, WAV and FLAC at common settings. Plan a podcast’s hosting cost, check an episode will fit an upload limit, or compare the cost of 192 kbps against 320 kbps.

Per-minute and per-hour figures make quick budgeting easy: for example an hour of 128 kbps MP3 is 57.6 MB, while an hour of CD-quality WAV is 635 MB.

How the Audio File Size Calculator works

size = bitrate × duration ÷ 8. WAV bitrates follow from the sample format (44.1 kHz × 16 bit × 2 = 1,411.2 kbps; 48 kHz × 24 bit × 2 = 2,304 kbps) plus a 44-byte header; FLAC is shown at about 60% of the PCM size, the usual average for music.

size (bytes) = bitrate (bits/s) ÷ 8 × duration (s)

What people use it for

Podcast hosting

Estimate monthly storage and bandwidth.

Upload limits

Check before exporting.

Library planning

Estimate collection size.

Delivery specs

Know what a master will weigh.

Tips for the best results

  • Opus at 96 kbps often matches 128+ kbps MP3 in quality at 25% smaller size.
  • FLAC size varies with the music — 50–70% of WAV.
  • Use ‘Fill from an audio file’ to read the real duration.

Common problems & fixes

The real file is a bit biggerTags, artwork and container overhead add a little.
VBR gives a different sizeVariable bitrate averages near the target but varies.

Quick facts

PresetsMP3 64–320 · AAC 256 · Opus 96 · WAV 16/44.1 & 24/48 · FLAC
OutputSize, bytes, per-minute, per-hour

Frequently asked questions

How big is a 3-minute MP3 at 320 kbps?

About 7.2 MB.

How big is a 3-minute CD-quality WAV?

About 31.8 MB.

How accurate is this estimate?

It's very close for constant-bitrate (CBR) MP3 and similar formats. Variable-bitrate (VBR) encoders can produce a somewhat smaller or larger file for the same nominal bitrate.

What bitrate should I use for good quality MP3?

192kbps is a common sweet spot for music; 128kbps is usually fine for spoken word/podcasts; 320kbps is closer to CD-quality for critical listening.

Your audio never leaves your device

This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.

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