Which Cable to Connect Two Macs? Thunderbolt 3, Thunderbolt 4, USB4 and the Traps
It's question number one at DiskBridge support, and the cause of nearly every "it doesn't work": the cable. A USB‑C cable can be a USB 2 charging cable (480 Mbit/s, no computer‑to‑computer link possible), a USB 3 cable (data, but no host‑to‑host mode), or a Thunderbolt / USB4 cable — the only kind that creates a Thunderbolt Bridge between two Macs.
How to spot a good cable
- The ⚡ lightning logo on the connectors with the number 3 or 4: Thunderbolt 3 or Thunderbolt 4. The most reliable marker.
- "USB4" together with "40 Gbps": a 40 Gbit/s USB4 cable works too (USB4 carries the Thunderbolt 3 protocol).
- The cable that came with a Thunderbolt display, dock or drive: almost always Thunderbolt.
- Apple's Thunderbolt 4 Pro cable (1 m or 3 m) and Thunderbolt 5 cables: yes.
Cables that won't work
- The USB‑C charging cable that came with a MacBook, an iPhone or a charger: it's USB 2; it charges, it doesn't link.
- A USB‑C cable rated "10 Gbps" or "20 Gbps" with no Thunderbolt logo: USB 3.x, no host‑to‑host mode.
- USB‑C to USB‑A cables: never.
- An older active "Thunderbolt" cable over 2 m (first‑generation Thunderbolt 3 active): it may cripple USB; prefer Thunderbolt 4.
What length?
Passive up to 0.8 m for 40 Gbit/s; between 0.8 and 2 m you need a certified Thunderbolt 4 cable (all of them guarantee 40 Gbit/s up to 2 m); beyond that, an active cable (Apple's 3 m Thunderbolt 4 Pro, or optical up to 30 m and more). For two Macs side by side, 0.8 m is plenty and costs less.
Older Macs: Thunderbolt 1 and 2
Macs from 2011 to 2015 have a Thunderbolt port shaped like Mini DisplayPort. They connect to a recent Mac with Apple's Thunderbolt 3 (USB‑C) ⇄ Thunderbolt 2 adapter plus a Thunderbolt 2 cable. The link drops to 10 or 20 Gbit/s, still far beyond Wi‑Fi. Those Macs can't install the DiskBridge app (macOS 13 required), but a "service" version exists for them — contact us.
Do I need a hub or a dock?
No, and it's best avoided: the host‑to‑host link must be direct, Mac to Mac. A USB‑C hub between the two prevents the Thunderbolt Bridge from coming up. A Thunderbolt dock in a chain can work, but nothing beats the direct cable.
Check in 10 seconds
Plug the cable into both Macs. Open System Settings › Network: "Thunderbolt Bridge" should turn to "Connected" (or "Self‑assigned IP") within seconds. If it stays "Not connected", change the cable before anything else. DiskBridge shows the same information in its Diagnostics window.
Our advice
A 0.8 to 1 m Thunderbolt 4 cable from a certified brand (Apple, Belkin, Cable Matters, OWC, Anker, CalDigit): US$25 to 70. It will also serve a Thunderbolt display or drive. With the right cable in hand, DiskBridge makes the other Mac's disks appear in the Finder the moment you plug in.
Get DiskBridge on the Mac App Store
More guides
- How to Connect Two Macs with a Thunderbolt or USB‑C Cable (2026)
How to link two Macs with a Thunderbolt 3, Thunderbolt 4 or USB4 cable, set up Thunderbolt Bridge and see the other Mac's disks in the Finder — manually, or automatically with DiskBridge.
- DiskBridge vs Intel Thunderbolt Share — Linking Two Computers with a Cable, on Mac and on PC
Intel Thunderbolt Share lets two Windows PCs talk over a Thunderbolt cable; DiskBridge does the same between two Macs. What each one does, what it costs, and why they are not interchangeable.
- Migrating to a New Mac over a Cable: Migration Assistant or Manual Copy?
How to move your data to a new Mac as fast as possible with a Thunderbolt cable, what Migration Assistant does well and badly, and how to keep using the old Mac afterwards.
- Moving Video Footage from a MacBook to a Mac Studio Without an External SSD
For editors and photographers — moving 4K/8K footage, RAW libraries and Final Cut, DaVinci or Lightroom projects from a laptop to a desktop workstation at Thunderbolt cable speed.