How long will it take to copy?
Enter the size and pick the link. We show the time at the theoretical speed and at a realistic estimate.
Click a row to watch the copy play out in fast-forward.
| Link or medium | Real speed | Time (realistic) | Time (theoretical) |
|---|
Why does a copy take longer than advertised?
- bits and bytes: 1 Gbit/s is 125 MB/s, not 1000.
- Many small files are much slower than one big file because each file has its own overhead.
- The slowest link rules: copying from a fast SSD to a cheap flash drive runs at the flash drive's speed. Flash drives and cards slow down a lot once their cache fills.
- Wi-Fi and mobile share the air with the neighbours and vary with distance.
- Protocol overhead: TCP/IP, encryption and the file system take about 5 to 10 %.
The "real" figures are typical estimates, not measurements of your gear. For your own number, time a big file and enter the speed above. With your own speed we use 90 % of it to allow for overhead.