File transfer time calculator
Pick a connection or type a speed, enter the size of what you are copying, and see how long it takes. Interface speeds are nominal, so turn on the efficiency option for a realistic estimate.
Nominal signalling rates. Real-world throughput is lower.
Off by default. Real transfers rarely reach the full advertised or nominal rate; 85–95% is typical on a good wired connection.
- Seconds80
- Minutes1.333333
- Hours0.0222222
The same file at other speeds
| Speed | Time |
|---|
Runs entirely in your browser. Nothing you type is sent anywhere.
How the transfer time is calculated
Transfer time is size divided by rate:
seconds = size in GB × 8,000 ÷ link speed in Mbps
The connection presets fill in the nominal signalling rate of each interface:
| Connection | Nominal rate | 100 GB at nominal rate |
|---|---|---|
| USB 2.0 | 480 Mbps | 27 min 47 s |
| Gigabit Ethernet | 1 Gbps | 13 min 20 s |
| 2.5GBASE-T | 2.5 Gbps | 5 min 20 s |
| USB 3.2 Gen 1 | 5 Gbps | 2 min 40 s |
| USB 3.2 Gen 2 / 10GBASE-T | 10 Gbps | 1 min 20 s |
| Thunderbolt 3/4 | 40 Gbps | 20 s |
These are best cases for the link alone. The efficiency option (90% by default, editable) scales the rate down, and for real copies it is worth lowering further when the storage is slow.
Worked examples
- Photo library to a USB 2.0 stick. 100 GB at 480 Mbps is 1,667 seconds, about 27 minutes 47 seconds, at the nominal rate. At 90% it is about 30 minutes 52 seconds, and a slow flash drive can make it much longer.
- Backup to a NAS over Gigabit Ethernet. 100 GB at 1,000 Mbps is 800 seconds. Using the typical 940 Mbps ceiling instead, it is about 851 seconds, or 14 minutes 11 seconds.
- Video footage over 10 GbE. 1 TB at 10,000 Mbps is 800 seconds (13 minutes 20 seconds), but only if both drives can read and write about 1.25 GB/s. Check drive speeds in GB/s to Mbps to see which side limits you.
Why copies miss the nominal rate
Nominal rates describe the wire, not the data you get. Encoding, packet headers and file-system work all take a share, and the copy can never go faster than the slowest part of the chain: the source drive, the destination drive, the cable, the port or the protocol. A hard drive or a cheap flash drive is often slower than a USB 3.2 or 10 GbE link. Many small files copy much more slowly than one large file of the same total size, because each file adds its own open, write and close steps.
After a copy, measure what you actually got with the network throughput calculator: enter the size and elapsed time and it shows the rate and how much of the link you used.
Tips
Plug into the fastest port both devices share; a USB 3.2 drive in a USB 2.0 port runs at USB 2.0 speed. Bundle many small files into one archive before a network copy. For internet downloads rather than local copies, the download time calculator is set up for plan speeds, and Mbps to Gbps helps compare a multi-gig plan with your local network.
Frequently asked questions
How long does it take to copy 100 GB over USB 3.2 Gen 1?
At the nominal 5 Gbps it takes 160 seconds, or 2 minutes 40 seconds. Real copies usually take longer because the drive, not the port, sets the pace.
Why is my USB copy so much slower than the port's rated speed?
The rated speed is the link's signalling rate. Encoding overhead, the drive's own read and write speed, and small files all slow the copy down. A slow drive limits any port.
Is Gigabit Ethernet faster than USB 2.0 for copying files?
On paper, yes: 1,000 Mbps against 480 Mbps. A 100 GB copy takes about 13 to 14 minutes over gigabit and at least 28 minutes over USB 2.0.