About this tool
Work out how long transferring a file will take, entirely in your browser. Enter the file size and pick its unit (KB, MB, GB, TB or the binary MiB/GiB), then enter your connection speed and its unit (Kbps, Mbps, Gbps, MB/s or GB/s). The estimated time updates live as a clean h/min/s breakdown plus the exact number of seconds.
The maths converts both figures to the same base — bits. Because one byte is eight bits, a 1 GB file is 8 billion bits, and a 100 Mbps line moves 100 million bits per second, so time = file-bits ÷ speed-bits-per-second. That 1 GB at 100 Mbps works out to 8,000,000,000 ÷ 100,000,000 = 80 seconds. The classic trap is bits vs bytes: ISPs quote megabits (Mbps) while download managers show megabytes (MB/s), and 1 MB/s equals 8 Mbps.
This is the theoretical best case. Real-world transfers are typically 10-20% slower because of TCP/IP and protocol overhead, latency, server limits, Wi-Fi loss and congestion, so treat the result as a floor and expect actual downloads to take a little longer.