Seeing SBC, AAC, aptX and LDAC on a spec sheet and wondering what matters? Bluetooth codecs explained simply: a codec compresses your music for the wireless trip, and both your phone and headphones must support the same one.
| Codec | Maximum bitrate (as reported) |
|---|---|
| SBC | Up to 345kbps |
| AAC | Up to 320kbps |
| aptX | 352kbps |
| aptX HD | 576kbps |
| LDAC | Up to 990kbps |
| CD-quality, uncompressed | 1411kbps |
These figures come from What Hi-Fi’s codec guide, last updated in November 2024. Specifications can change, so check the source before you rely on them.
What a Bluetooth codec actually does
Music files are large, and Bluetooth has limited bandwidth. A codec squeezes the audio on your phone, sends it, and your headphones unpack it.
Different codecs use different compression methods and bitrates. Bitrate is the rate at which data is transferred, measured in kilobits per second (kbps).
Uncompressed CD-quality audio has a bitrate of about 1411kbps. Compression can reduce that bitrate; lossy compression discards information, while lossless compression preserves it.
Lossy compression does not mean the audio sounds bad. A higher number on paper is not a guarantee of better sound in your ears, especially with everyday listening in a noisy place.
SBC: the codec everything supports
Every Bluetooth audio device supports at least one codec, and it is SBC. It is the most basic codec around, which is why you will find it on nearly every pair of earbuds.
It handles up to 16-bit/48kHz audio, with a bitrate up to 345kbps. Manufacturers often cap devices at 256kbps to avoid more battery drain.
The trade-off is lesser sound quality. Still, a well-tuned pair of headphones can sound good over SBC, and it is the fallback when your devices share nothing else.
AAC: the iPhone default
AAC is a more complex codec than SBC. Sound quality and power use depend on the implementation.
Apple uses AAC by default on iOS, but the format is not Apple’s property. AAC was developed as a successor to MP3. It can handle 24-bit/44.1kHz files with a bitrate of up to 320kbps. Android devices running Android 8 or later support it too.
Results vary by platform. Many listeners report that AAC behaves better on iPhones than on Android phones, so do not assume it beats SBC everywhere.
aptX and its variants
aptX comes from chipmaker Qualcomm. Dating to the late 1980s, aptX served broadcasting and film production before becoming widely used for Bluetooth listening.
The family has several members:
- aptX: a bitrate of 352kbps at 16-bit/44.1kHz.
- aptX HD: released in 2016, with support bumped to 24-bit/48kHz and a bitrate of 576kbps.
- aptX Adaptive: allows a compatible phone to use aptX HD when connecting to headphones that support that older codec.
- aptX Lossless: Qualcomm’s latest, with a bitrate that can scale between 1100 and 1200kbps.
aptX Low Latency is less commonly supported now, as it has essentially been folded into aptX Adaptive.
LDAC: the high-bitrate option
LDAC is Sony’s codec. LDAC’s reported limits are 990kbps for bitrate and 32-bit/96kHz for input audio.
Some recent Sony models use LDAC instead of aptX. To benefit, you need a phone that supports it, and a strong connection.
When the signal weakens, adaptive codecs drop their bitrate. Reducing bitrate can affect sound quality and help maintain the connection, though dropouts remain possible.
How to check which codec you are using
The simplest way to see what your devices support is to look at the spec sheet. On Android, the codec is chosen automatically, and you can override it in the developer menu.
- Open Settings, then About phone.
- Tap Build number to unlock developer mode.
- Go to Settings, System, Developer options, then Bluetooth audio codec.
iPhones support AAC and SBC, though you cannot switch between them. So pairing LDAC or aptX headphones with an iPhone means you will hear AAC or SBC.
Reading the numbers on a spec sheet
Spec sheets pile up three figures: bitrate, bit depth and sample rate. They describe different things, so it helps to separate them.
- Bitrate: how much data per second the codec sends. More data usually means less compression.
- Bit depth: how finely each sample of the sound is measured. Higher depth captures quieter detail.
- Sample rate: how many times per second the sound is measured, in kHz. Higher rates can capture higher frequencies.
A codec may “handle” a big file format yet still compress it hard. LDAC accepts hi-res files, but even its maximum bitrate is below that of uncompressed CD-quality audio.
Treat a headline spec as a ceiling, not a promise. Real-world links often run below it because of distance, interference and the device’s own settings.
Where codecs matter, and where they do not
A codec only shapes the wireless link between your phone and your headphones. It cannot add detail that the music file or streaming service never had.
A high-bitrate codec cannot restore detail missing from a low-quality track. The weakest link in the chain sets the ceiling.
Here is how the usual situations play out:
- Commuting or walking: background noise hides most differences between codecs, so SBC or AAC is usually fine.
- Quiet listening at home: a higher-bitrate codec such as LDAC or aptX HD has the best chance of showing a difference, if both devices support it.
- Video and gaming: delay matters more than bitrate. aptX Adaptive has absorbed the older low latency variant, so it is the family to look for.
- Weak signal: adaptive codecs lower their bitrate to hold the connection, so a crowded room can undo the benefit of a high maximum.
Battery life is the other cost. More complex codecs use more power, which is why some manufacturers cap their bitrate on small earbuds.
Which codec should you care about?
Start with a simple checklist: which phone you own, which headphones you are considering, and what you mostly listen to. If the phone and headphones share only SBC, you will hear SBC, whatever the box says.
Match the codec to your phone first. An iPhone user gains little from a headset’s LDAC support, while an Android owner with a matching headset may notice a difference.
Fit and seal often change what you hear more than the codec does. If you are still choosing a style, read our guide to types of headphones and the comparison of in-ear vs over-ear headphones.
Keep your gear in good shape too, because clogged mesh dulls sound. Our steps on how to clean earbuds show a safe routine.
Frequently asked questions
Is LDAC always better than AAC?
Show answer
No. LDAC has a higher maximum bitrate, but you need both a phone and headphones that support it, and a stable connection. On an iPhone it is not available at all.
Can I switch codecs on an iPhone?
Show answer
No. Apple’s phones pick between AAC and SBC on their own, and there is no menu to override that choice.
Why does my headset support a codec my phone does not use?
Show answer
Both devices must share a codec. If they do not, they fall back to SBC, which every Bluetooth audio device supports.
Does a higher bitrate mean better sound?
Show answer
Not always. Bitrate shows how much data a codec can send, but tuning, fit and your listening environment also shape what you hear.
