Calculating file transfer time across large distances

File transfer time isn't just dependent on file size and bandwidth.

If your destination is geographically far away, for example cross-country or maybe even located in another continent two other often missed factors can dramatically increase the file transfer time: latency and packet loss. In this article we explain those two factors and provide you a way to take them into account when calculating file transfer time.


Latency measures the time it takes for some data to get to its destination across a network. Usually when people talk about network latency they are referring to Round Trip Time (RTT). Latency is impacted by a number of factors including: distance from source to destination, the transmission mediums used such as WAN or fiber optic cables, and the routers used.

Packet Loss

When files are sent across the internet, they aren't sent in their entirety in one go. Instead they are first broken up into bite sized pieces of information called packets which are then sent to and reconstructed into the complete file at the destination. These packets can be lost or dropped for a variety of reasons, and when this happens the packet needs to be resent, and thus high packet loss can lead to slow file transfer. Packet loss is caused by factors including: faulty routers, lousy Wi-Fi signal, bandwidth restrictions, and network congestion.

Latency and Packet loss can increase file transfer time by a 1000x, when we send files to our editors in Munic, even though our own speed is great it takes days instead of hours.

To better take into the account of latency and packet loss, especially for cross country file transfer, we at Tachyon have built a file transfer time calculator. Try it out here