File Transfer Time Calculator

Not every large file transfer goes over the internet. Copying files to an external drive, moving a media library across a home network, or transferring data between two computers on the same LAN all have their own speed characteristics, often very different from internet download speeds. This calculator estimates transfer time across any of these connection types.

What the Result Means

Enter the size of the data you’re moving and the speed of the connection carrying it — whether that’s a local network link, a Wi-Fi connection, or a wired USB or Ethernet interface — and the calculator estimates how long the transfer should take. Unlike an internet download, many of these transfer types are capable of far higher sustained speeds, which changes the practical planning question from “will this take all evening” to “will this take a few minutes or a few seconds.”

This is especially useful for figuring out realistic timing for large jobs like transferring a full photo or video library to a new external drive, migrating files between two computers over a local network, or backing up a NAS.

How This Calculator Works

The approach is the same core division as internet download time, but the achievable speed depends entirely on the specific connection type involved:

• Gigabit Ethernet (1 Gbps): theoretical max ~125MB/s, with real-world sustained rates often in the 80-115MB/s range depending on hardware and drive speed.
• Wi-Fi: varies widely by standard and signal strength — commonly well below wired speeds, especially at distance or through walls.
• USB 3.0 external drive: theoretical max ~625MB/s (5 Gbps), though actual speed is usually limited by the drive itself rather than the USB interface.

Worked example: transferring a 500GB media library over a Gigabit Ethernet home network, with a real-world sustained rate of about 100MB/s:

• 500GB = 500,000MB
• 500,000MB ÷ 100MB/s = 5,000 seconds ≈ 83 minutes

Compare that to the same 500GB over a typical home Wi-Fi connection at, say, 30MB/s real-world — roughly 4.6 hours — a good illustration of why plugging in an Ethernet cable for a large one-time transfer is often worth the hassle.

Important Limitations

• The slowest link in the chain sets the pace. A fast network means little if the source or destination drive itself is the bottleneck — an older mechanical hard drive can cap a transfer well below what the network connection could otherwise support.
• Many small files transfer slower than one large file of the same total size. File-system overhead per file (especially over Wi-Fi or network shares) adds up, so a folder of thousands of small files often takes noticeably longer than a single large archive of equal size.
• Wi-Fi speed is highly situational. Distance from the router, interference, the number of other connected devices, and the Wi-Fi standard in use all affect real throughput, sometimes dramatically.
• Advertised interface speeds (like USB 3.0’s “5 Gbps”) are ceilings, not typical results. Real-world sustained speed is usually well below the interface’s theoretical maximum, particularly for USB flash drives and SD cards.