How to view a waveform
- Drop an audio file on the box. MP3, M4A, WAV, OGG, FLAC, WebM and the sound in MP4, MOV or MKV video can be opened.
- Set Detail (bars), from 50 to 4,000 (default 600).
- Pick a Colour for the bars.
- Press Draw waveform. The image appears with the file’s figures underneath; download it as an SVG.
What it does and when to use it
A waveform is the fastest way to understand a recording without listening to all of it. Editors use it to find the start of speech, a cough or a long silence. Podcasters compare episodes to see whether one is much quieter. Musicians spot clipped masters, where the bars are flat against the top and bottom. Designers use the SVG for podcast covers, audiograms and posters.
The figures under the picture are a quick health check: a Peak at 0 dBFS hints at clipping, and a Loudness far below −16 LUFS means a spoken file may need lifting with the audio normaliser. For file details such as bitrate, tags and cover art, use the audio metadata viewer. To cut a section you found on the waveform, open the file in the audio trimmer.
How it works
The file is decoded in a Web Worker on your device; WAV directly, other formats through your browser’s WebCodecs decoder. The samples are split into as many equal time slices as you chose bars, and for each slice the tool takes the lowest and highest value across all channels. Each bar is drawn from that minimum to that maximum, so a quiet slice is a short bar and a loud one fills the height. The figures are calculated from the full decoded audio: sample peak, RMS across all channels, and integrated loudness per ITU-R BS.1770-4. Nothing is uploaded.
Worked example
A 5-second mono test memo, with 2 s of tone at −6 dBFS, 1 s of silence and 2 s of quieter tone, gave:
| Figure | Value |
|---|---|
| Duration | 0:05.000 |
| Sample rate | 44,100 Hz |
| Channels | 1 |
| Peak | −6 dBFS |
| RMS | −12.8 dBFS |
| Loudness | −10.3 LUFS |
| Codec | WAV · PCM 16-bit |
The SVG showed a tall block, a flat gap and a short block, and downloaded as memo.wav-waveform.svg. RMS comes out lower than Loudness here because RMS averages in the silent second and the quiet part, while the loudness gates leave both out.
Limits and tips
- The whole file is decoded into memory before drawing, about 21 MB per minute of stereo audio, so very long files can fail on phones.
- Loudness shows “—” for audio shorter than 0.4 s or almost silent.
- This tool has no ffmpeg fallback. AIFF, AMR, WMA and CAF files need converting first with audio to WAV.
- Without WebCodecs (older browsers) only WAV files can be read.
Frequently asked questions
What can I learn from the waveform?
How many bars should I use?
Can I use the SVG in a design?
What is the difference between Peak, RMS and Loudness?
How do we know nothing is uploaded? Test it yourself on the privacy proof page.