Free tool
Transfer Time Calculator
Enter a file size and a connection speed to estimate download or upload time.
Estimated time
8m 53s
Internet speeds are usually advertised in bits per second (Mbps) — file sizes are measured in bytes. This calculator converts between them for you.
Estimating transfer time trips people up for one reason: file sizes are measured in bytes, but internet speeds are almost always advertised in bits — a “100 Mbps” connection is 100 megabits per second, not 100 megabytes per second. Since there are 8 bits in a byte, that connection tops out around 12.5 MB/s in practice, not 100 MB/s.
This calculator converts between the two for you, so you can go straight from “I have a 20 GB file and a 300 Mbps connection” to a real answer in minutes and seconds.
How to use it
- 01Enter the file size and pick its unit (MB, GB or TB).
- 02Enter your connection speed and pick its unit — bits per second (Kbps/Mbps/Gbps) or bytes per second (KB/s/MB/s/GB/s).
- 03Read the estimated time. This is a theoretical maximum — real transfers are usually a bit slower.
Frequently asked questions
Why is my 100 Mbps connection so much slower than 100 MB/s?
Because Mbps measures bits and MB/s measures bytes, and there are 8 bits per byte. A 100 Mbps connection has a theoretical maximum of 100 ÷ 8 = 12.5 MB/s — a common point of confusion when shopping for internet plans.
Does this account for real-world network conditions?
No — this is the theoretical maximum at your rated speed. Actual transfer speed is usually lower due to network overhead, server-side limits, Wi-Fi conditions and other traffic sharing your connection. Expect 70–90% of the theoretical number in practice.
What's the difference between Mbps and MB/s?
Mbps (megabits per second) is how internet speeds are marketed. MB/s (megabytes per second) is how your operating system usually reports transfer progress. To convert Mbps to MB/s, divide by 8.
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