Enter a file size and transfer rate.
Speed & transfer
File Transfer Time Calculator
Plan a local or network transfer from the rate your drive or connection reaches.
What does the File Transfer Time Calculator do?
It estimates how long copying data will take when you know the transfer rate – for example moving a photo library to an external drive, backing up to a NAS or copying files across a local network.
The formula
Time = file size ÷ transfer rate. If the rate is in Mbps the tool divides by 8 to work in bytes, so MB/s and Mbps inputs both give a correct answer.
Example
Copying 50 GB at 80 MB/s takes 50,000 ÷ 80 = 625 seconds – about 10.4 minutes.
What sets your transfer rate?
The slowest part of the chain wins: a hard drive, a USB port, a Wi-Fi link, a 1 Gbps Ethernet port (about 110–115 MB/s in practice) or the disk on the receiving side. Many small files are also slower than one large file of the same total size.
FAQ
Frequently asked questions about the File Transfer Time Calculator
How long does it take to copy 1 TB?
At 100 MB/s, 1 TB (1,000,000 MB) takes 10,000 seconds, roughly 2.8 hours.
Why is copying many small files slower?
Each file adds overhead for opening, writing and closing it, so small files rarely reach the drive's headline speed.
What is a realistic speed over gigabit Ethernet?
Around 110–115 MB/s, because the 125 MB/s theoretical limit is reduced by protocol overhead.
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Use this toolResults are estimates for planning. Last reviewed 20 September 2026.