Free ACX Audio Checker
Drop an audiobook file and see whether it passes ACX/Audible's audio requirements — RMS level, peaks, noise floor, sample rate, and duration — before you submit and wait days for a rejection.
100% private: analysis runs in your browser. Your audio never leaves your device.
Drop your audiobook file here
or click to browse — MP3, WAV, FLAC, M4A, AAC, OGG
What this checks
ACX runs every submitted file through an automated audio analysis. Files outside the required ranges are rejected — often days after you submit. This tool measures the same core specs locally: RMS between -23 dB and -18 dB, peaks no hotter than -3 dB, a noise floor at or below -60 dB RMS, 44.1 kHz sample rate, and a maximum of 120 minutes per file. Final delivery must be 192 kbps or higher constant-bitrate MP3.
For the full requirements — including room tone at the head and tail of each file and consistent mono/stereo across your book — read our complete ACX requirements guide.