Audio File Size Estimator | Compare WAV, FLAC, MP3 and AAC Sizes
Estimate how big the same recording becomes in 10 formats at once — WAV, AIFF, FLAC, ALAC, MP3, AAC, OGG and Opus — and see each one's compression ratio against the raw PCM source.
💡 About this tool
Choosing an audio format is a trade-off between size and quality, and the only way to judge it honestly is to see the numbers for your recording. A three-minute stereo track at CD quality is about 30 MB as WAV but only 8 MB as a 320 kbps MP3 — and that gap widens fast for hour-long podcasts or multi-track sessions.
This estimator takes your duration, sample rate (22,050 to 192,000 Hz), bit depth (16/24/32-bit) and channel count, then lays out the resulting file size for ten formats grouped by type: uncompressed (WAV, AIFF), lossless (FLAC, ALAC) and lossy (MP3 at 320/192/128k, AAC 256k, OGG 192k, Opus 128k). The uncompressed PCM size is shown as a reference, and each row carries a compression ratio so you can see, at a glance, that FLAC lands near 55% of the original while a 128 kbps lossy file may be a tenth of it. Click any row to read a short note on what that format is good for.
🧐 Frequently Asked Questions
How is the uncompressed size calculated? Raw PCM size = duration in seconds × sample rate × (bit depth ÷ 8) × channels. That figure is exact and forms the baseline for every ratio shown.
Are the FLAC and ALAC sizes exact? No. Lossless compression depends on the actual audio content, so those rows use a typical ratio (around 50–60% of PCM). Quiet or repetitive material compresses more; dense, noisy material compresses less.
Why are the lossy sizes the same regardless of sample rate? MP3, AAC, OGG and Opus here use a constant bitrate, so their size depends only on bitrate × duration, not on the source sample rate or bit depth. That is why a 320 kbps file is always about 2.4 MB per minute.
Which format should I pick for archiving? For a master you plan to edit later, keep WAV or FLAC — both are lossless. FLAC is roughly half the size of WAV with no quality loss, which is why it is a common archival choice.
Does the ratio use base-1000 or base-1024? The displayed sizes use binary units (KB/MB based on 1024). The percentage ratio is size relative to the uncompressed PCM figure, so the unit base cancels out.
📚 How lossy and lossless differ
Lossless formats such as FLAC and ALAC work like a ZIP file for audio: they find redundancy and pack it away, and decoding rebuilds the original samples bit-for-bit. That is why their size depends on the music itself and cannot be predicted exactly in advance.
Lossy codecs take a different route. They model what the ear can and cannot hear and discard the parts it will not miss — a process called perceptual coding. Because they target a fixed bitrate, their size is wonderfully predictable, but the discarded data is gone for good. Opus is the most efficient of the bunch, often matching older codecs at half the bitrate, which is why streaming and voice apps have embraced it.