WhatsApp Audio Compressor

This compressor finds the highest-quality MP3 that fits under WhatsApp’s 16 MB media limit. You give it a recording; it works out the maximum bitrate from the duration, picks sensible channel and sample-rate settings, encodes, and measures the real size — stepping down until the file is truly under the limit.

WhatsApp allows media — including audio files sent from the gallery or file picker — up to about 16 MB. Anything larger is refused or must be sent as a document (which allows up to 2 GB but does not play inline). Speech mode is on by default because most WhatsApp audio is voice.

Size = bitrate ÷ 8 × duration, so the budget is bitrate = limit × 8 ÷ duration. The tool uses a 1.5% safety margin for MP3 frame overhead, picks the largest legal MP3 bitrate that fits, switches to mono below roughly 112 kbps (speech: 80 kbps) and to 22.05/16 kHz at very low rates for better quality per bit, then encodes for real and checks the byte count. If it is still over, it steps one bitrate down and repeats (up to five times). Sizes use decimal megabytes (1 MB = 1,000,000 bytes), the stricter and safer interpretation for upload limits.