Download Time Calculator

File size is converted to bits (bytes times 8), then divided by your speed in bits per second. A 5 GB file is 40 billion bits; a 100 Mbps line moves 100 million bits per second, so the theoretical time is about 400 seconds. The calculator handles the unit conversion so you don't multiply or divide by 8 by hand.

Real downloads never hit the theoretical maximum. Protocol overhead, server throttling, Wi-Fi loss, and congestion typically cost 10-20%, so the realistic estimate adds about 15%. If a specific server is slow or capping your speed, the real time can be far longer than either figure.

Not exactly. This tool uses decimal GB (1,000,000,000 bytes), matching how speeds are advertised. Operating systems often report binary GiB (1,073,741,824 bytes) but label it GB, making files look about 7% larger. The difference shifts the estimate slightly but the method is the same.