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Why AirDrop is slow with large files, and what’s faster

AirDrop is slow with large files because it sends over a wireless link, at about 320 Mb/s between Macs in published tests. For big projects, a Thunderbolt cable between the two Macs is many times faster, though the built-in way to use it takes some setup.

Why AirDrop is slow with large files

  • It’s wireless. AirDrop uses a direct Wi-Fi link between the two Macs. Published Mac-to-Mac tests put it around 320 Mb/s, and about 700 Mb/s at best. At 320 Mb/s, 100 GB takes over 40 minutes.
  • It shares the radio with your Wi-Fi. The Mac switches between AirDrop’s link and your Wi-Fi network, so a busy network, walls or distance slow both.
  • Folders are packed first. AirDrop packs a folder into one archive before sending it, so a big folder can wait a while before any progress shows.
  • No resume. If either Mac sleeps, moves out of range or cancels, the transfer fails and you send it again from the start.
  • Someone has to accept it. Unless both Macs use the same Apple Account, the receiving Mac has to click Accept.
  • Apple only. AirDrop doesn’t work with Windows or Linux.

Get the most from AirDrop

These steps help a large AirDrop transfer finish:

  1. Put the two Macs close together, in the same room, with nothing in between.
  2. Plug both Macs into power.
  3. On a Mac laptop, open System Settings, choose Battery, click Options and turn on Prevent automatic sleeping on power adapter when the display is off.
  4. Sign both Macs into the same Apple Account, so transfers are accepted without a click.
  5. If the Macs use different accounts, open Control Centre on the receiving Mac, click AirDrop and choose Everyone for 10 Minutes.
  6. Optional: pause anything else using Wi-Fi on both Macs, such as downloads, backups or AirPlay.
  7. Send several medium-sized batches rather than one huge folder, so a failed transfer costs less.

Use a Thunderbolt cable instead

If both Macs have Thunderbolt or USB4 ports, a cable between them gives a private network link called Thunderbolt Bridge. Between two Macs we measured 37.7 Gb/s each way on the cable itself. To copy files over it with macOS, you turn on File Sharing on one Mac and connect from the other.

On the Mac that has the files

  1. Connect the Thunderbolt cable between the two Macs.
  2. Open System Settings, choose General, then Sharing, and turn on File Sharing.
  3. Click the info button next to File Sharing. Under Shared Folders, click + and add the folders you want to copy.
  4. Under Users, check that your user account has Read & Write or Read Only access. You sign in with this account’s name and password, so it needs a password.
  5. In System Settings, choose Network, then Thunderbolt Bridge, then Details. Note the IP address under TCP/IP. It starts with 169.254.

A 169.254 address and a “Self-assigned IP” status are normal for a direct cable. There’s no router to hand out addresses.

On the Mac that receives the files

  1. In Finder, choose Go > Connect to Server.
  2. Type smb:// followed by the address you noted, for example smb://169.254.10.20, and click Connect.
  3. Choose Registered User, enter the other Mac’s user name and password, and click Connect.
  4. Select the shared folder and click OK. It opens in Finder and appears in the sidebar.
  5. Drag the files you want into a folder on this Mac.

What to watch for

  • Connecting by name can use Wi-Fi. If you pick the other Mac from Finder’s Network list, Finder may find its Wi-Fi address, and the copy runs over Wi-Fi instead of the cable. Connect by the 169.254 address.
  • The firewall can block it. If Block all incoming connections is on in the firewall options (System Settings, Network, Firewall), File Sharing can’t accept the connection.
  • Small files are slow. File sharing handles each file with several back-and-forth requests. In our tests, Finder took almost four minutes to copy 20,000 small files from a Mac to a Linux computer over a 10 Gb/s link.
  • Sleep and unplugging end the connection. After either Mac sleeps or restarts, or the cable comes out, you connect and sign in again.
  • The address can change. The self-assigned address can be different after you reconnect the cable, so a saved server address may stop working.

More detail, including Share Disk and Migration Assistant, is in transferring files with Thunderbolt.

Other ways to move big files

  • Ethernet: both Macs on a wired network with File Sharing, at up to about 1 Gb/s on most networks. The setup is the same as above, using each Mac’s network address.
  • A fast external SSD: copy the files on, then off. It needs no wireless or sharing, but you copy everything twice.

Compare times for each in the fastest way to transfer large files.