How do I calculate download time?
Divide the file size in bits by the speed in bits per second. For example, a 1 GB file contains 8 billion bits. At a constant 100 Mbps, the theoretical transfer time is 80 seconds. This calculator also lets you choose a lower effective speed to allow for overhead and other limitations.
What is the difference between Mbps and MB/s?
A byte contains eight bits. Broadband plans usually quote megabits per second, written Mbps. Many download apps show megabytes per second, written MB/s. In decimal units, 100 Mbps equals 12.5 MB/s before overhead. Choosing the correct unit avoids an eightfold error.
Are GB and GiB the same size?
No. A gigabyte (GB) is 1,000,000,000 bytes. A gibibyte (GiB) is 1,073,741,824 bytes. Some software uses labels loosely, so check which convention the reported file size uses. This calculator keeps decimal KB/MB/GB/TB and binary KiB/MiB/GiB/TiB separate.
Why is my actual download slower than the estimate?
Wi-Fi signal, other users, VPNs, server limits, protocol overhead and your device’s storage can affect a transfer. Advertised broadband speed is not a promise that one file server will send at that rate. The 90% default is an illustration, not a predicted efficiency. Enter your measured speed from the speed test and adjust the allowance to compare scenarios.
Can I calculate upload or backup time too?
Yes. Enter the size of the data being sent and your upload speed. Use the total size for a batch of files, allowing extra time for many small files, connection setup or a backup app that scans or compresses data first. The estimate covers data transfer rather than those additional tasks.
Does the calculator download anything to test my connection?
No. It only does the calculation in your browser. No files, file names, entered sizes or calculated results are uploaded or added to Analytics event values. For a measured snapshot, use the optional internet speed test. For intermittent delays, try the connection stability monitor.