Guides

The fastest way to transfer large files between two computers

A Thunderbolt or USB4 cable between the two computers is the fastest way: 100 GB can cross in minutes. It needs those ports on both computers and some file-sharing setup. Without them, an Ethernet cable or a fast portable SSD beats Wi-Fi, AirDrop and cloud storage.

Why this is harder than it should be

• Cloud storage copies everything twice. Files go up to a server and back down again, and home upload speeds are usually a fraction of download speeds. A 100 GB project can take most of a day.
• Wi-Fi is slower than its rating. A Wi-Fi 6 router may be sold as 1.2 Gb/s or more, but computer-to-computer copies often run at 100–320 Mb/s, because each file crosses the air twice.
• AirDrop is convenient but slow for big jobs, and it only works between Apple devices.
• External drives mean copying twice, plus finding a drive with enough space and formatting it so both computers can use it.
• Small files make everything worse. Network file sharing handles files one at a time. A folder of 20,000 small files took almost four minutes over SMB in our tests, on a link that moves one large file of the same size in seconds.
• The fastest option needs the most setup. A cable only gives you a network connection. You share a folder, change network settings, find a self-assigned address and sign in, then connect again after every sleep or restart.

How long 100 GB takes

Best-case times, calculated from each method’s typical rate. Real copies are slower, especially for folders with many files.

Which to choose

• Both computers have Thunderbolt or USB4: use a cable. Check with how to tell if your laptop has Thunderbolt or USB4, then follow the setup below.
• No compatible ports, but both have Ethernet: connect them to the same wired network and share a folder.
• Neither: a fast portable SSD formatted as exFAT. Copy, eject, copy again.
• Small amounts, different places: cloud storage.

Set up a cable transfer with built-in file sharing

Connecting two computers with a Thunderbolt or USB4 cable creates a network connection between them. Nothing appears in Finder or File Explorer until you share a folder on one computer and connect to it from the other. Use a Thunderbolt 3 or newer, or USB4, cable. A phone charging cable won’t work.

Share a folder on the computer that has the files

On a Mac:

1. In System Settings, choose General > Sharing and turn on File Sharing.
2. Click the info button (ⓘ) next to File Sharing, then add the folders to share and set who can read or write them.
3. If a Windows PC will connect, click Options…, select your account under Windows File Sharing and enter its password.

On a Windows PC:

1. In File Explorer, right-click the folder and choose Properties.
2. On the Sharing tab, click Share…, choose who can open the folder, then click Share.
3. In Settings, choose Network & internet > Advanced network settings > Advanced sharing settings.
4. Under Private networks, turn on Network discovery and File and printer sharing.

On Linux, share the folder with Samba. That means installing it, adding the share, setting a Samba password for your account and allowing it through the firewall. See transferring files between a Mac and Linux.

Find the address on the cable connection

With no router on the cable, each computer gives itself an address starting with 169.254. That’s normal, and it’s the address you connect to.

• On a Mac: in System Settings, choose Network > Thunderbolt Bridge. It shows Self-assigned IP. Click Details… to see the address.
• On Windows: the cable appears as a new Ethernet connection, usually labelled Unidentified network and set to Public, which blocks file sharing. In Settings, choose Network & internet > Ethernet, select the connection and set Network profile type to Private network. The IPv4 address is listed on the same page.
• On Linux: the cable appears as a wired connection named thunderbolt0. In its IPv4 settings, set the method to Link-Local Only, then read the address from the connection’s details.

Connect from the other computer

On a Mac:

1. In Finder, choose Go > Connect to Server.
2. Enter smb:// followed by the other computer’s cable address, for example smb://169.254.12.34, and click Connect.
3. Choose Registered User, enter the name and password of an account on the other computer, and click Connect.
4. Select the shared folder. It opens in Finder and appears under Locations in the sidebar.

On a Windows PC:

1. In the File Explorer address bar, type \\ followed by the address, for example \\169.254.12.34, and press Enter.
2. Enter the name and password of an account on the other computer, and select Remember my credentials. The shared folders appear.

On Linux, open Files and choose Network in the sidebar (Other Locations in older versions). Enter smb:// followed by the address in the box at the bottom, click Connect and sign in.

Reconnect after sleep, restart or unplugging

The shared folder disconnects when either computer sleeps, restarts or loses the cable. Connect again the same way. On a Mac, Go > Connect to Server keeps a list of recent servers. On Windows, a mapped network drive with Reconnect at sign-in selected comes back after a restart, though it can show as disconnected until you open it.

A self-assigned address can change after the cable is unplugged. If connecting fails, check the address again. See why network shares disconnect after sleep.

Common problems with cable file sharing

• The other computer doesn’t show up under Network. Connect by its cable address instead. On Windows, check that the cable connection is set to Private. See File Explorer can’t see the other computer.
• The copy runs at Wi-Fi speed. If you connect by computer name, or pick the computer from the Network list, the copy can go over Wi-Fi instead of the cable. Connect using the 169.254 address, or turn off Wi-Fi for the copy.
• Your password is refused. A Windows PC signed in with a Microsoft account wants that account’s email address and password, not your PIN. An account with no password can’t sign in over the network.
• Copies run well below the cable’s speed. Windows 11 version 24H2 and later require SMB signing by default, which costs speed on fast links. Mac and Windows aren’t tuned for each other either. See why file sharing over Thunderbolt runs below the cable’s speed.
• Folders of small files crawl. SMB took almost four minutes to copy 20,000 small files over a 10 Gb/s link in our tests. Zip them first, then copy the zip.

Getting the most from a cable

• Use a Thunderbolt or USB4 cable rated 40 Gbps, not a phone cable.
• Copy to a fast internal SSD. A slow receiving drive caps the whole transfer.
• Check the copy is going over the cable, not Wi-Fi, by connecting to the cable address.