Find the internet speed you need to transfer a file in a given time, or how long a transfer takes at a given speed.
Required speed
How to use this tool
Enter the data size and choose MB, GB or TB.
Enter the time available and choose seconds, minutes or hours.
Add protocol overhead under advanced options if you want a safety margin.
Read the required speed in Mbps and MB/s, plus time per GB.
Formula & worked example
Transferring 10 GB in 10 minutes needs 133.33 Mbps (16.67 MB/s); with 10% protocol overhead the line speed needed is 146.67 Mbps.
Limitations — read this before you rely on it
Idealised calculation: it assumes a constant speed with no throttling, congestion, Wi-Fi loss or server limits, so treat the result as a minimum line speed.
Frequently asked questions
Network speeds are quoted in decimal bits per second, so this tool uses 1 GB = 1,000 MB. If your file size is in GiB, multiply by 1.074 first.
Headers, retransmissions and encryption add bytes beyond the file itself, so the line speed must be higher than the raw data rate.
Server limits, Wi-Fi, congestion and other devices sharing the connection all reduce the speed one transfer actually gets.
Use the same idea in reverse: a 25 Mbps stream needs a connection comfortably above 25 Mbps once other household use is added.
Yes for sending files: the same calculation applies, using your upload speed instead of download speed.