How this calculator works
File size is converted to bits and divided by effective bits per second. Effective speed is the entered connection speed multiplied by your efficiency percentage. At the default 100%, no loss is assumed; lower efficiency increases transfer time. The estimate assumes constant effective throughput. Latency, congestion and server limits can vary during a transfer.
The formula
Effective bits/second = connection bits/second × efficiency / 100
Seconds = file bytes × 8 / effective bits/second
1 Mbps = 1,000,000 bits/s; 1 MB/s = 8,000,000 bits/s.A quick example
A decimal 1 GB file at 100 Mbps takes 80 seconds ideally: 1 minute 20 seconds. At 100 MB/s, it takes 10 seconds.
How to use this calculator
- Enter file size and its decimal or binary unit.
- Enter positive speed and choose bits/s or bytes/s units.
- Calculate ideal time and allow for real-world overhead.
Planning adjustments
Connection efficiency adjusts the entered speed. At 100% the result assumes full throughput; at 80% the same file takes 25% longer. Choose your own efficiency rather than assuming a fixed network loss.
A few common questions
Is Mbps the same as MB/s?
No. A megabyte contains eight megabits; 100 MB/s equals 800 Mbps.
Does this include network overhead?
The default 100% assumes no loss. You can enter a lower efficiency to model reduced effective throughput; actual overhead is not measured by this tool.
Why can my download be slower?
Wi-Fi conditions, server capacity, competing traffic and protocol overhead can reduce sustained throughput.