Data Transfer Speed Calculator
Calculate transfer time from file size and connection speed - correctly distinguishes Mbps (megabits/sec) from MB/s (megabytes/sec).
Enter a file size and your connection speed - this tool correctly converts between bits-per-second (Mbps) and bytes-per-second (MB/s) to estimate transfer time.
Mbps (megabits per second) is how internet speeds are usually advertised; MB/s (megabytes per second) is how download progress is usually shown - 1 byte = 8 bits, so 100 Mbps is only 12.5 MB/s, not 100 MB/s. Real-world transfer time varies due to network conditions, protocol overhead, and other traffic - this is a theoretical estimate assuming a sustained, uninterrupted speed.
Real-world transfer time is almost always longer than this calculation due to protocol overhead, network congestion, and other factors - this shows the theoretical best case based on the numbers you enter.
Why Mbps ≠ MB/s
Internet connection speeds are almost always advertised in megabits per second (Mbps), while file sizes are measured in megabytes (MB) - since 1 byte = 8 bits, a 100 Mbps connection transfers at most 12.5 MB per second, not 100 MB. Confusing the two leads to a transfer-time estimate that's off by a factor of 8.
How to Use It
- Enter your file size and its unit.
- Enter your connection speed and specify whether it's in bits-per-second or bytes-per-second units.
- View the estimated transfer time.
Important Notes
This is a theoretical best-case calculation based on the numbers you provide - actual transfer time is virtually always longer in practice due to protocol overhead, network congestion, and other real-world factors this tool has no way to measure.