Moving Files Between Two Computers

Moving a large amount of data between two machines is one of those tasks where the obvious method is often the slowest. The right choice depends on how much data, how often, and whether both machines are in the same room.

Direct network transfer, same network

The fastest option for most people, and consistently overlooked.

If both machines are on the same network, data can move between them directly at the speed of the network, without touching the internet.

On Windows: enable network discovery and file sharing, right-click the folder, choose Properties, then Sharing, then share it. The other machine reaches it through Network in File Explorer, or by typing the machine name in the address bar.

On macOS: System Settings, General, Sharing, then File Sharing. The other Mac connects through Finder's Network section, or with Go, then Connect to Server.

Between Windows and macOS: this works, because both speak SMB. Connect from the Mac using smb:// followed by the Windows machine's name or address.

Speed: on wired gigabit, expect around 100 MB per second in practice — 100 GB in roughly twenty minutes. On Wi-Fi, considerably less and highly variable.

An Ethernet cable directly between the machines

If you have a lot to move and no fast network, connect the two machines with a single Ethernet cable.

Modern network ports handle the crossover automatically, so an ordinary cable works. Both machines will assign themselves link-local addresses within a minute or two, and file sharing works exactly as above.

This gives you the full speed of the slower network port with no other traffic competing. For a one-off migration of several hundred gigabytes it is the best option available without buying anything.

External drive

Simple, universally understood, and slower than people assume because the data is written twice.

The trap is file systems. A drive formatted NTFS is read-only on macOS without extra software. A drive formatted APFS or HFS+ is unreadable on Windows. exFAT works on both and is the right choice for a drive that will move between them.

Speed depends on the connection and the drive. A USB 3 SSD moves data quickly. A USB 2 port or a mechanical drive is far slower, and for very large transfers a network transfer will beat it.

Cloud storage

Convenient, and the wrong tool for bulk transfer.

The data goes up to a server and back down. Home upload speeds are typically a fraction of download speeds, so a 50 GB upload can take many hours. If both machines are in the same building, the data is travelling a very long way for no reason.

Where it does make sense: small to moderate amounts, machines in different places, or an ongoing sync rather than a one-time move.

One caution: if you are moving files by syncing a folder, wait for the upload to complete before wiping the source. A sync client showing files locally does not mean they are safely on the server.

Transfer over the internet, machine to machine

For moving data between distant machines without a cloud intermediary, several tools establish a direct connection and encrypt it end to end. Some are browser-based and require nothing installed; others are command-line tools that give you a short code to type on the other side.

These are well suited to sending a large file to someone else once. They are limited by the sender's upload speed, so the same caveat applies as with cloud storage.

Built-in migration tools

For moving to a replacement machine rather than moving individual files, the operating system's own tool is usually the right choice, because it moves settings and accounts as well as data.

Windows has limited built-in migration; most people move files manually or use the backup and restore path.

macOS has Migration Assistant, which will move a whole user account, applications and settings from another Mac or from a Time Machine backup. Over a direct cable or a wired network it is genuinely good.

Choosing quickly

Under a gigabyte, same room: a USB stick, or a network share.

Under a gigabyte, different places: cloud storage or a direct transfer tool.

Ten to a hundred gigabytes, same network: a network share, ideally wired.

Several hundred gigabytes: direct Ethernet cable between the machines, or an external SSD.

Replacing a machine: the operating system's migration tool.

Ongoing, repeated: set up a sync tool once rather than repeating a manual copy.

Two things that save grief

Verify before deleting. Count the files at both ends, and check total size. A transfer that reported success can still have skipped files whose names contain characters the destination file system dislikes.

Watch for path length limits on Windows. Deeply nested folders can exceed the traditional limit and fail partway. Copying to a short destination path first avoids it.

Mistakes people make

Using cloud storage for a transfer between machines in the same room. The data travels to a data centre and back, limited by an upload speed that is usually a fraction of the download speed.

Deleting the source before verifying. Compare file counts and total size at both ends. Transfers report success while having skipped files with awkward names.

Formatting a shared external drive as NTFS or APFS. One of the two machines will only be able to read it, or not see it at all. exFAT works on both.

Forgetting Windows path length limits. Deeply nested folders fail partway through a copy. Copy to a short destination path first.

Trusting a sync client's file list. A file shown locally is not necessarily uploaded. Wait for the client to report completion.

The short answer

Same network: share a folder and copy directly, ideally over a cable. Very large one-off transfer: an Ethernet cable between the two machines. Different locations: cloud or a direct transfer tool. Replacing a machine: the operating system's migration tool.