The aptX codec family in numbers: classic aptX carries 352 kbps of 16-bit audio at up to 48 kHz, with an official THD+N of -67 dB and SNR of 93 dB. aptX Adaptive adjusts between 279 and 420 kbps with a low-system-latency mode of approximately 80 ms. aptX Lossless is a Snapdragon Sound capability targeting CD-quality 16-bit 44.1 kHz lossless audio at about 1 Mbps, with no standalone spec page of its own. Independent testing measured classic aptX at 316 ms of lag on an Android rig. iPhones negotiate AAC and SBC only.
Figures on this page were checked September 2026. Every table row carries its source and access date.
Spec summary
aptX is Qualcomm's original Bluetooth audio codec, documented on Qualcomm's official aptX page with a full technical specification sheet.
| Field | Value | Source / as of |
|---|---|---|
| Developer | Qualcomm (Qualcomm Technologies, Inc.) | aptX official page, 2026-09-22 |
| Bit rate | 352 kbps (48 kHz sampling) | aptX official page, 2026-09-22 |
| Audio encoding | 16-bit, up to 48 kHz sampling rate | aptX official page, 2026-09-22 |
| THD+N @ 1 kHz | -67 dB | aptX official page, 2026-09-22 |
| SNR @ 1 kHz | 93 dB | aptX official page, 2026-09-22 |
| PEAQ audio quality | -0.18 | aptX official page, 2026-09-22 |
| Frequency range | 20 Hz to 20 kHz | aptX official page, 2026-09-22 |
| DSP load | Kalimba DSP: 42 MHz stereo decode, about 45 MHz stereo encode at 48 kHz | aptX official page, 2026-09-22 |
| Consistency | Fixed compression ratio; interoperability testing program for aptX-enabled products | aptX official page, 2026-09-22 |
The spec sheet still carries the codec's DSP-era details, down to Kalimba core clock loads. The fixed compression ratio is the trait that matters for listeners: a constant 352 kbps payload behaves the same way on every link, which is what Qualcomm's interoperability testing program checks.
The five aptX forms
The brand now spans five forms. One of them, aptX HD, has its own profile on this site.
| Form | Cited rate | Depth / ceiling | Source / as of |
|---|---|---|---|
| Classic aptX | 352 kbps, fixed | 16-bit, 48 kHz | aptX official page + SoundGuys table, 2026-09-22 |
| aptX HD | 576 kbps, fixed | 24-bit, 48 kHz | aptX HD official page, 2026-09-22 |
| aptX Adaptive | Typically 279-420 kbps, dynamic | 24-bit / 96 kHz per third-party table | aptX Adaptive official page (rate) + SoundGuys table, 2026-09-22 |
| aptX Low Latency | No rate published on the official page | 16-bit audio quality | aptX Low Latency official page, 2026-09-22 |
| aptX Lossless | 1,200 kbps maximum per third-party table | 24-bit / 96 kHz per same table | SoundGuys table; no standalone official spec page, 2026-09-22 |
Rates for classic, HD and Adaptive come from Qualcomm's own pages. The Low Latency page publishes no bitrate, and Lossless has no page at all, so those two rows lean on what third parties print. The cross-codec rate view is our bitrate bench.
aptX Adaptive in numbers
Adaptive is the current-generation form, documented on its own official page.
| Field | Value | Source / as of |
|---|---|---|
| Latency | Low system latency, approximately 80 ms | aptX Adaptive official page, 2026-09-22 |
| Bit rate | Typically 279 kbps to 420 kbps, adjusting to radio conditions and content | aptX Adaptive official page, 2026-09-22 |
| Backwards compatibility | aptX and aptX HD in stereo headsets; aptX in earbuds and stereo headsets | aptX Adaptive official page, 2026-09-22 |
| Listening evidence | Salford University test (June 2018), quoted on the official page: no statistically significant difference between aptX Adaptive at 420 kbit/s and linear audio at 24-bit/96 kHz | aptX Adaptive official page, 2026-09-22 |
Its spec sheet lists no bit-depth or sample-rate figure, so the 24-bit/96 kHz ceiling in the family table above is third-party table data. The Salford quote is the codec owner's summary of its commissioned test, the same reading rule as on the HD page.
aptX Lossless status
Lossless is the form without a spec page of its own. The aptX family navigation lists Adaptive, HD, Low Latency and classic aptX, and a dedicated Lossless URL redirects to the Snapdragon Sound intro. The numbers below come from the September 2021 press release that introduced the technology.
| Data point | Status | Source / as of |
|---|---|---|
| Standalone product page | None in the aptX family navigation | aptx.com site structure, 2026-09-22 |
| Official design | A new capability of aptX Adaptive and a feature of Snapdragon Sound, designed to deliver CD-quality 16-bit 44.1 kHz lossless audio over Bluetooth | Qualcomm press release (body text via Internet Archive snapshot of the official URL), 2026-09-22 |
| Published bit rate | About 1 Mbps, scaling down to 140 kbit/s in congested RF environments | Qualcomm press release, 2026-09-22 |
| Operating modes | User-selectable: CD lossless at 44.1 kHz, or 24-bit 96 kHz lossy | Qualcomm press release, 2026-09-22 |
| Availability | Announced September 2021, expected late calendar 2021 | Qualcomm press release, 2026-09-22 |
| Third-party table row | 1,200 kbps maximum, 24-bit / 96 kHz | SoundGuys comparison table, 2026-09-22 |
| Windows 11 | Named among codecs not natively supported; requires special drivers | Microsoft Learn Q&A, 2026-09-22 |
| Independent latency measurement | Not covered by the RTINGS bench | RTINGS not-covered list, 2026-09-22 |
Qualcomm markets Lossless as a Snapdragon Sound capability instead of a standalone codec with a rate card. Note where the sources disagree in emphasis: the press release puts the rate at about 1 Mbps with the 24-bit 96 kHz mode marked lossy, while the third-party table prints a 1,200 kbps maximum with 24-bit/96 kHz listed without that qualifier. Read the table row as a third-party characterization, not an official rate.
Measured latency
| Metric | Measured | Source / as of |
|---|---|---|
| Classic aptX average | 316 ms, 25.7 ms typical variance across four Android phones | SoundGuys (Bluetooth receiver + instrumentation rig, not headphones), published 2021-03, accessed 2026-09-22 |
| aptX Adaptive low-latency mode | "<80 ms is appreciably low" | RTINGS bench verdict (Adaptive Low Latency mode, not classic aptX or aptX LL), accessed 2026-09-22 |
| Direct aptX HD and aptX LL numbers | Not covered; the bench replaced HD with Adaptive (High Quality) and LL with Adaptive (Low Latency) | RTINGS Test Bench 1.6 change log, 2026-09-22 |
| Consistency | "Most implementations of aptX (any form) should be reasonably consistent and predictable" | RTINGS latency research, accessed 2026-09-22 |
The only anchored number for the classic form, 316 ms, puts it in the same lag class as SBC and Sony's LDAC on the same rig. The newer Adaptive low-latency mode is the exception on the bench, where the verdict runs "<80 ms is appreciably low", measured from a USB transmitter dongle its authors suggest is more efficient than a smartphone source. For film and gaming, the low-latency picks in our Bluetooth audio delay guide remain the faster path. The cross-codec record sits in our latency bench.
Device and OS support
| Platform / device | aptX support | Source / as of |
|---|---|---|
| Android phones | Phones and tablets fill much of the official product list; current entries include Sony Xperia 10 VIII, REDMI and Sharp models | aptX official page product list, 2026-09-22 |
| iPhone | No; iPhones negotiate AAC and SBC only | SoundGuys codec support article, 2026-09-22 |
| Windows PCs | aptX HD, Adaptive and Lossless named among codecs not natively supported in Windows 11; special drivers required | Microsoft Learn Q&A, 2026-09-22 |
| Headphones and home audio | Headsets (Fostex T50RP-BT) and home units (Rotel Michi P430) appear on the same official list | aptX official page product list, 2026-09-22 |
Pairing behavior
A link runs an aptX form only when both ends advertise it. Adaptive is listed as backwards compatible with aptX and aptX HD in stereo headphones, which covers the common mismatch of a new phone meeting an older headphone. Where nothing advanced matches, the link settles on SBC, and an iPhone source lands on AAC regardless of what the receiver supports. Per-model phone detail lives in our iPhone codec compatibility page.
FAQ
The classic aptX codec runs at a fixed 352 kbps with 16-bit audio up to 48 kHz. aptX Adaptive moves to a dynamic range of 279 to 420 kbps and adds a low-system-latency mode of approximately 80 ms, with backwards compatibility to aptX and aptX HD in stereo headphones. Measurement programs have shifted too: the RTINGS bench now tests Adaptive in place of both aptX HD and aptX LL.
Not on Qualcomm's own site. The aptX family navigation lists Adaptive, HD, Low Latency and classic aptX, with no standalone Lossless page. The 2021 announcement describes it as a capability of aptX Adaptive that delivers CD-quality 16-bit 44.1 kHz lossless audio at about 1 Mbps, and Windows 11 does not support it natively.
No. iPhones negotiate AAC and SBC only, so an aptX-capable receiver falls back the moment the source is an iPhone. Our iPhone codec compatibility page has the per-model detail.
The classic aptX codec measured 316 ms on average on a four-phone Android rig that used a Bluetooth receiver and instrumentation, not headphones. RTINGS, whose bench replaced the older aptX variants with aptX Adaptive, describes most aptX implementations of any form as reasonably consistent and predictable. For video sync, low-latency chains are the faster path; our Bluetooth audio delay guide covers the options.
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- Qualcomm aptX official page: Bit Rate 352kbps (48kHz sampling), Audio Encoding 16-bit up to 48kHz, THD+N@1kHz -67dB, SNR@1kHz 93dB, PEAQ -0.18, Kalimba DSP 42MHz decode / ~45MHz encode, fixed compression ratio, 20Hz-20kHz, interoperability testing program. aptx.com/aptx, accessed 2026-09-22
- Qualcomm aptX Adaptive official page: Low system latency approx. 80ms, bit rate typically 279kbps to 420kbps, backwards compatible with aptX and aptX HD in stereo headsets and with aptX in earbuds and stereo headsets, Salford University test results June 2018. aptx.com/aptx-adaptive, accessed 2026-09-22
- aptx.com site structure: aptX types navigation lists aptX Adaptive, aptX HD, aptX Low Latency and aptX only; no standalone aptX Lossless product page; Snapdragon Sound described with support for lossless and high-res music streaming. aptx.com, accessed 2026-09-22
- Qualcomm press release (September 1, 2021): aptX Lossless introduced as a new capability of aptX Adaptive and a feature of Snapdragon Sound, designed to deliver CD quality 16-bit 44.1kHz lossless audio over Bluetooth; bit-rate about 1Mbps, scaling down to 140kbits/s in congested RF; user-selectable CD lossless 44.1kHz or 24-bit 96kHz lossy; availability expected late calendar 2021. qualcomm.com/news/releases/2021/09/01/qualcomm-adds-bluetooth-lossless-audio-technology-snapdragon-sound (live page metadata; body text via Internet Archive snapshot 2022-01-03 of the same URL), accessed 2026-09-22
- SoundGuys, Bluetooth codec support for headphones: comparison table rows (aptX 352kbps/16-bit/48kHz, aptX Adaptive 279-420kbps/24-bit/96kHz, aptX Lossless 1200kbps/24-bit/96kHz) and "iPhones only support the AAC and SBC Bluetooth codecs." soundguys.com/bluetooth-codec-support-headphones-61989/, accessed 2026-09-22
- SoundGuys, "Android's Bluetooth latency needs a serious overhaul": classic aptX 316 ms average and 25.7 ms typical variance across four Android phones; measured with a Bluetooth receiver and instrumentation, not headphones. soundguys.com/android-bluetooth-latency-22732/, accessed 2026-09-22
- RTINGS, "Test Bench 1.6: Latency R&D Article": most implementations of aptX (any form) reasonably consistent and predictable; Test Bench 1.6 dropped aptX HD in favor of aptX Adaptive (High Quality) and replaced aptX-LL with aptX Adaptive (Low Latency); aptX-LL and aptX Lossless listed among codecs not covered; low-latency codec mode described as appreciably low at under 80 ms. rtings.com/headphones/learn/research/latency, accessed 2026-09-22
- Microsoft Learn Q&A, Bluetooth codecs supported in Windows 11: "Advanced codecs like aptX HD, aptX Adaptive, aptX Lossless, and LDAC are not natively supported in Windows 11. These require special drivers or external solutions." learn.microsoft.com/en-us/answers/questions/5560825/, accessed 2026-09-22