How to check an audio file's length
- Open your files. Tap Open audio files and pick one or more recordings, or drop them onto the tool on a computer. MP3, M4A, WAV, AAC, OGG, FLAC and WebM all work in most browsers.
- Read the length. Each file shows its length as hours, minutes and seconds, its total minutes, its size and its format. With two or more files, a total row adds them up.
- Check the limits. Under each file, see whether it fits VoiceScriber's 90-minute limit, the OpenAI API's 25 MB upload limit and Otter's free plan. Copy the results as plain text if you need them elsewhere.
Other ways to check audio length
On a Mac
In Finder, select the file and press Command-I to open Get Info. The length is listed as Duration under More Info. You can also open the file in QuickTime Player and choose Window > Show Movie Inspector. In Terminal, afinfo file.m4a prints an estimated duration in seconds.
On Windows
In File Explorer, switch to Details view, right-click any column heading, choose More… and tick Length. Every audio file in the folder then shows its length. For a single file, right-click it, choose Properties and open the Details tab.
On iPhone
Voice Memos shows the length of each recording in its list. For other audio in the Files app, tap the file to preview it, and the player shows the full length. To check many files at once or get a total, open them with the tool above in Safari.
On the command line
With FFmpeg installed, this prints the length in seconds on any operating system:
ffprobe -i file.mp3 -show_entries format=duration -v quiet -of csv="p=0"Frequently asked questions
How do I check the length of an MP3 without uploading it?
Open the file with the tool above. It reads the length inside your browser, so the MP3 never leaves your device. You can also check it with tools already on your computer: Get Info on a Mac, the Length column in Windows File Explorer, or ffprobe on the command line.
Why does my MP3 show the wrong length?
Most often the MP3 was encoded with a variable bitrate (VBR) and has no header that records how long it is. Players then estimate the length from the first few seconds, so two apps can show different times. Files that were cut or copied incompletely can also report the length of the original. Re-saving the file in an audio editor, or remuxing it with ffmpeg -i in.mp3 -c copy out.mp3, usually fixes the reported length.
How long is a 10 MB MP3?
It depends on the bitrate. At 128 kbps, a common setting, 10 MB holds about 11 minutes of audio, roughly a minute per megabyte. At 64 kbps, which many voice recorders use, it is about 22 minutes. At 192 kbps it is about 7 minutes, and at 320 kbps about 4 minutes. Open the file above to see its exact length.
Can I check Voice Memos recording length on iPhone?
Yes. The Voice Memos app shows the length of each recording in its list. To check several recordings at once or see their total, save them to the Files app with the Share button, then tap Open audio files above in Safari and pick them. Voice Memos recordings are M4A files.
Can it add up the length of several audio files?
Yes. Select or drop as many files as you like. Each file gets its own row, and a total row adds up the length, the minutes and the size. Copy results gives you the table as plain text.
Is my file uploaded?
No. The length is read by your browser on your device, and the audio is never sent to our servers or anyone else. We count anonymous usage, such as how many files were checked and their file types, but never file names or contents.
Does it work on Android?
Yes. It works in Chrome and other Android browsers. Tap Open audio files and pick recordings from your phone's storage, your recorder app's folder or Google Drive.