What's the real speed of Bluetooth 5.1 file transfer?

rambomhtri · 04 Jun 2021

Hi, I'm quite disappointed with the current Bluetooth speed I am getting for a zip file (sequential transfer) or any "large" file. My setup is as good as it can get, or pretty close to the best:
- MSI MPG Z390 GAMING PRO CARBON AC: almost the latest Intel chipset paired with a built-in Intel Wireless-AC 9560, which supports 802.11 a/b/g/n/ac, MU-MIMO Rx, 2.4GHz/ 5GHz (160MHz) up to 1.73Gbps, and Bluetooth 5.1.
- Xiaomi Poco F2 Pro: Android 11, Qualcomm SM8250 Snapdragon 865 5G (7 nm+), Bluetooth 5.1, A2DP, LE, aptX HD, aptX Adaptive...

As you can see, Bluetooth 5.1 is the best one right now, except for some phones that are starting to come with 5.2 version. The hardware, CPU and other things are top tier so I don't know why my speeds are so slow. I remember I did a test about 5 years ago with BT 4.2 between a medium-end $700 laptop and a low end smartphone and I got 150KB/s. Pretty slow but that was it. Now, with the hardware up there, I am transferring a 136MB zip file to my Poco F2 Pro in 20 min. Which means I am transferring at 113KB/s...

I do understand that Bluetooth transferring is not meant to be used to transfer your whole 4K video 40GB library of the phone to the PC, but I think it's more than fair enough to transfer a bunch of pictures made with the Poco to the PC, let's say 20 pics, which is about 150MB. Pretty basic task, very common, nothing crazy here. There is no way you have to wait 20 minutes to transfer 20 pics in 2021 with the top tech of the market.

I've read that the max speed of BT 5.1 is 2Mbps, which is about 250KB/s, still very slow in 2021 to be honest, but more than twice of what I am getting. In case it was something about WiFi interfering or something (my PC has WiFi built in), I disabled the WiFi and transferred a 10MB file, and reached stable 140KB/s during the whole transfer, which was about 74 seconds. Clearly having the WiFi on affects the speed, but still, it is pretty slow. I am getting the exact same performance I had with a low-end smartphone of 2015 and $700 laptop from 2013. We are in 2021. It can't be that this has not evolved.

First question is, how am I getting with a much better hardware and newer revisions of bluetooth the same speed than 5 years ago?

Second question, can you do the same, with a 10MB file or something, and calculate your speed of transferring?
(you should share the devices you used and their BT version)

rambomhtri · 07 Jun 2021

Somebody?

Samuria · 07 Jun 2021

You are right with your speed the main thing with 5.1 is direction and range Latest Bluetooth 5.0 To 5.1 How Is It Different & How It Works (Guide)

pmelo · 03 Dec 2022

The purpose of Bluetooth connection is for low energy data transfer/streaming. Audio being perhaps the most common use, requires as "high" as approximately 320kbit/s, according to the AAC codec used in Spotify, under the Very high quality setting. You really don't gain much (if anything at all) in terms of audible quality from that to raw .wav files.
https://support.spotify.com/uk/article/audio-quality/

Therefore, the up to 2Mbit/s of Bluetooth 5.1 is more than enough to handle it without breaking a sweat, and that's enough. According to this link Bluetooth 5.1 has a data throughout of up to 1.4Mbits/s, though, so I guess that it might vary a little depending on the device's implementation too.
Higher SpeedHow Fast Can It Be? | Bluetooth(R) Technology Website

Note here I assume we're happy with stereo audio over Bluetooth. This link explains why we can't have true surround 5.1 audio over Bluetooth:
How Many Audio Channels Does Bluetooth Support? (2.0, 2.1, 5.1, etc.)

The only occasions of data transfer in these devices are configuration profiles, and being married to a sound engineer I know how much the speakers manufacturers optimise their whole systems through R&D so that such files are the smallest it can be, so their products are plug and play and as autonomous as they can be.

Wearables, smart watches only need small amount of data as well. I imagine json files with data from weather forecast would be in the 10kb ballpark, and not much more for heart sensor kind of data. Perhaps it can get complicated when it comes to roomba kind of room mapping for autonomous hoover, but I imagine these might have hardware and storage to do the heavier computations on the actual device, leaving the data transfer mostly for commands and authentication, profiles, etc (again, small files).

Printers are the only devices I can think of that could do the bad decision of using Bluetooth to receive the pdf images to print. However, the one I know and own (HP Envy, but I believe that's the common industry practice too), uses wi-fi direct for the first setup and then it sets up a wi-fi local server to receive the data supposed to be printed, not Bluetooth.

In the early days of Bluetooth, I felt it wasn't clear which direction it would take, and using Bluetooth would drain a phone's battery very quickly. So, the industry quickly realised that's not the way to transfer big files. Wi-fi is there for that.

So, long story short, from my understanding the reason for this is that Bluetooth is designed for low data transfer, and improvements should come for extra range, richer metadata, features, reliability, power draw (low energy), mesh pairing and syncing, etc. If you want to send files, use cable, wi-fi or wi-fi direct 😉

What's the real speed of Bluetooth 5.1 file transfer?

What's the real speed of Bluetooth 5.1 file transfer?

That's by design. Speed is not the point