Step 1: Drop your MP3 files using the button above or by deposit and leave.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Receive your converted M4R files.
MP3 to M4R Conversion FAQ
What bitrate does the M4R file use?
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A lossy M4R is encoded at 192 kbps by default. The Audio Quality setting also offers 320 kbps for the best quality and 128 kbps for a smaller file. A lossless M4R (WAV, FLAC) ignores the bitrate and keeps every sample.
Is converting MP3 to M4R a second round of lossy compression?
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Yes, and it is worth planning around. Both formats are lossy, so the M4R encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the M4R from that instead avoids the double pass entirely. MP3 is lossy: a psychoacoustic model discards frequencies the ear is unlikely to notice, typically at 128 to 320 kbps. The payload is AAC, conventionally capped at 40 seconds, which is the longest tone iOS will accept.
Will going from MP3 to M4R reduce my audio quality?
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If MP3 is lossy and M4R is lossless (e.g. MP3 → WAV), the M4R file is no better than the MP3 — you can't recover information that's already been thrown away. If MP3 is lossless and M4R is lossy, expect the M4R codec to recompress; at 192 kbps this is transparent for most content.
Can I batch convert hundreds of MP3 files to M4R?
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Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
Will the M4R keep the same sample rate as MP3?
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By default yes (48 kHz MP3 → 48 kHz M4R). If you need to downsample for compatibility (e.g. 96 kHz → 44.1 kHz for CD burning) the advanced sample-rate option does this with high-quality resampling.
Can I normalize loudness in the MP3 to M4R step?
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Not in this step. The converter has no loudness setting and leaves the level as it is. To even out the volume, run the finished M4R through a Normalize tool on this site.
Will the M4R play on my car stereo / iPod / audiobook app?
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MP3 plays almost everywhere. AAC plays on Apple devices, most Android phones and Sonos. FLAC plays on Sonos and Android but not on older iPods, and WAV plays on nearly everything but makes large files. There are no device presets on this page, so choose the target format your player supports.
Is my MP3 file private during conversion?
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Yes. Nobody listens to or shares the audio, which matters for personal audiobook libraries, and uploaded MP3 files and their converted copies are deleted automatically about 24 hours after conversion.
How long does converting a 10-hour audiobook MP3 to M4R take?
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It depends on the size and length of the file. Small documents and images are usually ready quickly. Long videos take the longest, because most video conversions re-encode every frame.
Why is the M4R file louder / quieter than the MP3 source?
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The converter does not change the level: it has no gain or normalize setting. If you hear a difference, your player or media library is probably applying ReplayGain or its own volume levelling on playback; switch that off to hear the M4R as it is.
