DirectConnectTest results
Real copies between Mac, Windows PC and Linux computers on one cable. Every copy checked byte for byte on the receiving computer.
Fast copy, Mac to Mac
Two M1 MacBook Airs on a 40 Gb/s Thunderbolt cable, copying in both directions.
| Copy | Fast copy | Through the drive |
|---|---|---|
| 2,000 small files (53 MB) | 0.25–0.52 s | 2.1–5.4 s |
| One 1 GiB file | 12.5–20.7 Gb/s | 8.6–10.3 Gb/s |
The same 2,000 files take 0.80–0.90 s to copy within one Mac, so fast copy between two Macs is faster than copying on one. Long copies settle at the receiving drive’s write speed.
Against network file sharing
Finder copies of one large file and a folder of 20,000 small files over a 10 Gb/s link.
20,000 small files
331 MB total · Time to copy
6.9×faster than SMB file sharing
- DirectConnectMeasured · 10 Gb/s Thunderbolt
- 34.4 s
- macOS SMB → SambaMeasured · 10 Gb/s Thunderbolt
- 3 min 57.8 s
Small-file overhead matters.
Shorter is faster · Each chart has its own time scale
Solid = measured · Striped = calculated
One large file
4 GiB (4.3 GB) · Time to copy
4.3 snear cable speed
- DirectConnectMeasured · 10 Gb/s Thunderbolt
- 4.3 s
- macOS SMB → SambaMeasured · 10 Gb/s Thunderbolt
- 4.5 s
- Gigabit EthernetTheoretical minimum · 1 Gb/s line rate
- ≥34 s
- AirDropEstimated · 40 MB/s · Apple devices only
- ~1 min 47 s
- Wi-Fi 6Estimated · SMB via router · 250 Mb/s
- ~2 min 17 s
Ethernet shows a theoretical minimum; wireless times are estimates. Setup and storage overhead are excluded.
Shorter is faster · Each chart has its own time scale
Solid = measured · Striped = calculated
Finder copies from an M1 MacBook Air to a Linux computer over 10 Gb/s Thunderbolt: DirectConnect against the Mac’s built-in file sharing to a Linux Samba server.
Calculated large-file times use 4 GiB divided by the stated rate, excluding setup, preparation and storage overhead. AirDrop is Apple-only and is not a Mac → Linux route. Wi-Fi and AirDrop rates are published reference points, not guaranteed speeds. Sources and assumptions are under “About these numbers”.
How it compares
Large-file transfers between computers. Longer bars are faster.
| Method | Speed in bits per second | Speed in bytes per second | Time to move 100 GB |
|---|---|---|---|
| DirectConnect40 Gb/s Thunderbolt cable | 40 Gb/sgigabits per second5 GB/sgigabytes per second5,000 MB/smegabytes per secondCable rating. Copies run slower. | 5 GB/s | as little as 20 s* for 100 GB |
| DirectConnect10 Gb/s USB-C cable | 8 Gb/sgigabits per second1 GB/sgigabytes per second1,000 MB/smegabytes per second8 bits (b) = 1 byte (B). Cables are sold in bits per second; file copies show bytes per second. | 1 GB/s | 1 min 40 s for 100 GB |
| macOS SMB → Samba10 Gb/s link | 7.6 Gb/sgigabits per second950 MB/smegabytes per secondMac to a Linux Samba server. | 950 MB/s | 1 min 45 s for 100 GB |
| Mac file sharing (SMB)Wi-Fi 7, both computers on Wi-Fi | 1 Gb/sgigabits per second125 MB/smegabytes per secondIdeal-condition estimate. Published laptop-to-wired tests reached 1.6–2.2 Gb/s; two wireless computers share airtime. Small files will be slower. | 125 MB/s | 13 min for 100 GB |
| AirDroptypical | 320 Mb/smegabits per second40 MB/smegabytes per secondPublished reference. Around 700 Mb/s is possible nearby with no competing Wi-Fi traffic. | 40 MB/s | 42 min for 100 GB |
| Mac file sharing (SMB)Wi-Fi 6, both computers on Wi-Fi | 250 Mb/smegabits per second31.25 MB/smegabytes per secondEstimate within reported 100–320 Mb/s router-based copies. Small files will be slower. | 31 MB/s | 53 min for 100 GB |
Measured Rated or estimated Gb/s ÷ 8 = GB/s · Right column: time to move 100 GB
* Cable rating. Real copies are slower.
The slowest part sets the pace.
- ReadSending drive
- TransferCable and ports
- WriteReceiving drive
A 10 Gb/s link copies at about 8 Gb/s. Drive caches can slow long transfers.
What a 40 Gb/s cable gives you
40 Gb/s is the speed in each direction, over two 20 Gb/s lanes. Between two Macs, the cable itself carried 37.7 Gb/s each way.
Some computer pairs connect over only one lane, which gives about 20 Gb/s each way. A Linux laptop and a Mac did this on the same cable, at 16.3–17.8 Gb/s.
Copies run below the cable’s speed, because the drives and the copy itself take their share. Mac-to-Mac copies run at up to 20.7 Gb/s.
Typical drive speeds
- Hard drive
- 0.8–2 Gb/sgigabits per second100–250 MB/smegabytes per second8 bits (b) = 1 byte (B). Cables are sold in bits per second; file copies show bytes per second.
- SATA SSD
- 4 Gb/sgigabits per second500 MB/smegabytes per second8 bits (b) = 1 byte (B). Cables are sold in bits per second; file copies show bytes per second.
- NVMe SSD
- 8+ Gb/sgigabits per second1+ GB/sgigabytes per second1,000+ MB/smegabytes per second8 bits (b) = 1 byte (B). Cables are sold in bits per second; file copies show bytes per second.
Typical sequential writes, not guaranteed rates.
Windows PC and Mac, through the drive
A Mac copying to and from a Windows PC’s shared folder, a Dell Latitude 5430 with Windows 11 and an M1 MacBook Air on USB4.
| Copy | Mac to Windows PC | Windows PC to Mac |
|---|---|---|
| 3 GiB folder, fast copy | 16.6–21.8 Gb/s | – |
| 3 GiB folder, Finder | 8.2–10.8 Gb/s | – |
| One 1 GiB file, Finder | 8.0–8.9 Gb/s | – |
| One 1 GiB file, fast copy | 15.9–19.0 Gb/s | – |
| One 1 GiB file, Terminal copy | 12.2–12.9 Gb/s | 10.3–10.5 Gb/s |
| One 40 GB file, Terminal copy | 5.9–6.0 Gb/s | – |
Finder takes a moment to start each copy. That’s why the 3 GiB folder ran faster than the single 1 GiB file. Fast copy is DirectConnect’s own copy, for files you drop on the other computer in the DirectConnect window.
The 40 GB copy runs at the speed of the PC’s disk: on its own, the disk writes 40 GB at 7.95 Gb/s.
Linux computer and Windows PC
A Lenovo ThinkPad P1 with Fedora Linux and a Dell Latitude 5430 with Windows 11, on one 20 Gb/s USB4 lane. Copies started on the Windows PC.
| Copy | Windows PC to Linux | Linux to Windows PC |
|---|---|---|
| One 1 GiB file, fast copy | 16.3–17.3 Gb/s | 14.5 Gb/s |
| One 1 GiB file, File Explorer | 12.1–12.3 Gb/s | 9.8–10.4 Gb/s |
| 2,000 small files, fast copy | 0.16–0.21 s | 0.30–0.31 s |
| 2,000 small files, File Explorer | 4.5–4.6 s | 4.7–4.8 s |
Started on the Linux computer, fast copy brings the 1 GiB file over at 11.1–14.5 Gb/s and the 2,000 files in 0.10–0.12 s.
Linux computer and Mac
A Dell Latitude 5430 with Fedora Linux and an M1 MacBook Air, on Thunderbolt.
| Fast copy | Started on Linux | Started on the Mac |
|---|---|---|
| One 1 GiB file, from the other computer | 15.4–17.4 Gb/s | 12.4–14.6 Gb/s |
| One 1 GiB file, to the other computer | 12.8–13.5 Gb/s | 11.0–14.3 Gb/s |
| 2,000 small files, from the other computer | 0.08–0.11 s | 0.15–0.25 s |
In Finder, the Mac copies the 2,000 files to the Linux computer in 3.3–3.6 s and from it in 1.7–1.9 s.
Sending files, Mac to Mac
Send files to a computer set to Receive only. Two M1 MacBook Airs on a Thunderbolt cable.
| Send | Time or speed |
|---|---|
| 2,000 small files (53 MB) | 1.2–1.7 s |
| One 1 GiB file | 9.8–10.5 Gb/s |
Small files from a Windows PC, the first time
Microsoft Defender scans each file on a Windows PC the first time any program opens it. A folder of 2,000 small files that Defender hadn’t scanned copied from a Windows PC to a Mac in 18.8 seconds. The next copy took 1.3 seconds. See Known issues on Windows.
Cable speed by computer pair
Raw network speed over the cable, before files or DirectConnect are involved. Each pair used its own cable.
| Computers | Link | Raw TCP, Gb/s |
|---|---|---|
| Mac ↔ Mac | Thunderbolt, 40 Gb/s, two lanes | 37.7 each way |
| Windows ↔ Mac | USB4, 40 Gb/s | Mac → Windows 24.2, Windows → Mac 12.0 |
| Windows ↔ Mac (Dell) | USB4, 20 Gb/s adapter | DirectConnect link test: Mac → Windows 20.5–23.3, Windows → Mac 21.4–22.6 |
| Linux ↔ Mac | 40 Gb/s cable, one 20 Gb/s lane | Linux → Mac 17.8, Mac → Linux 16.3 |
| Linux ↔ Windows | USB4, one 20 Gb/s lane | Linux → Windows 17.3, Windows → Linux 4.0 |
A 40 Gb/s link runs two 20 Gb/s lanes, and each lane carries data both ways at once, so 40 Gb/s is the ceiling in each direction. When a pair comes up on one lane, the ceiling is 20 Gb/s each way.
About these numbers
Speeds are ranges from repeated copies, in decimal units. Every copy was checked byte for byte on the receiving computer.
The comparison with network file sharing uses Finder copies from an M1 MacBook Air to a Linux computer over a 10 Gb/s Thunderbolt link: a folder of 20,000 files (331 MB) and one 4 GiB file. File sharing used the Mac’s built-in SMB client and a Samba server on Linux.
Striped bars are calculations, not copies: 4 GiB divided by the stated rate, without setup time. Gigabit Ethernet uses its 1 Gb/s line rate. AirDrop uses a 40 MB/s published Mac-to-Mac figure from Eclectic Light. Wi-Fi 6 uses 250 Mb/s, within the computer-to-computer range reported in the TP-Link community.
Bits and bytes
Lowercase b means bits; uppercase B means bytes. Divide bits by 8: 8 Gb/s = 1 GB/s. Cables and network ratings use bits; file sizes use bytes. The (i) buttons on this page show both.
Why long copies slow down
An SSD may fill its fast cache or get hot. The slower drive limits the transfer, even with a fast cable.