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Data Transfer Time Calculator

Estimate how long a download or upload takes from a file size and connection speed. Factors in transfer efficiency to show a realistic effective-speed estimate.

Input

Data size

Unit

Transfer speed

Unit
%

Result

Estimated transfer time

1 min 26 sec

(85.9 seconds total)

Data size (bits)

8,589,934,592 bit

Effective speed

100 Mbps

Data size (bytes)

1,073,741,824 byte

Data size (in bits)8,589,934,592 bit
Data size (bytes)1,073,741,824 byte
Nominal speed100 Mbps
Effective speed (with efficiency)100 Mbps
Transfer time85.9 seconds

How it works

  • Transfer time is found as 'data size (bits) divided by speed (bps)'. File sizes are usually given in bytes, so the value is multiplied by 8 to convert it to bits before calculating.
  • The unit bps means 'bits per second' while the file-size unit byte means 'byte', where 1 byte = 8 bits. Note that even on a 100 Mbps line the theoretical maximum download is only about 12.5 MB per second.
  • Connection speed (such as Mbps) uses decimal units where 1 Mbps = 1,000,000 bps, while file size (KB/MB/GB) uses binary units where 1 KB = 1,024 bytes. Because the systems differ, the result can deviate slightly from a simple division.
  • Transfer efficiency estimates what fraction of the nominal speed is actually achieved due to congestion, overhead, wireless conditions and so on. In practice it is often around 50-80%, and lowering the efficiency increases the time required.
  • The displayed time is only a theoretical estimate. Actual times vary with server-side limits, concurrent connections, storage write speed and other factors.