How to use this calculator
Enter decimal gigabytes and the connection speed in megabits per second. Use upload speed for an upload and download speed for a download. The throughput percentage allows for overhead and conditions that reduce useful speed.
The formula
A worked example
Transferring 2 GB at 20 Mbps and 80% usable throughput takes 1,000 seconds, or 16 minutes 40 seconds.
Assumptions & limitations
Assumes a constant effective transfer rate. One GB is 1,000,000,000 bytes here; GiB is a different unit. Server limits, connection changes, retries, and compression can affect real time.
Common questions
Are Mbps and MB/s the same?
No. There are 8 bits in a byte. At 100% throughput, 20 Mbps is 2.5 decimal MB/s.
Can I estimate download time too?
Yes. Use the download speed instead of upload speed.
Units reference
The calculation follows the method above. This reference supports the units and conversions.
NIST: binary prefixes and decimal units ↗Formula and worked example checked against automated test cases. About our methodology.