File Transfer Time Calculator
Enter the file size and the connection speed to get the transfer time. You can also set an efficiency, the share of the nominal speed you expect to get in practice.
How the transfer time is calculated
The transfer time is the file size divided by the amount of data that can be sent per second.
- Transfer time (seconds) = size (bits) ÷ (speed (bits per second) × efficiency ÷ 100)
- Size (bits) = size (bytes) × 8
Bits and bytes: Mbps vs MB/s
Connection speeds are usually quoted in bits (bps, Mbps, Gbps), while file sizes are usually quoted in bytes (MB, GB). One byte is 8 bits.
- 100 Mbps is 100,000,000 bits per second, which is 12,500,000 bytes per second, or 12.5 MB/s.
- A download speed shown in MB/s (as many browsers and apps do) is 8 times the figure in Mbps: 1 MB/s = 8 Mbps.
In this calculator, k, M and G in a speed are powers of 1,000 (1 Mbps = 1,000,000 bits per second), and 1 MB/s is 1,000,000 bytes per second. For file sizes, KB, MB and GB are powers of 1,000, and KiB, MiB and GiB are powers of 1,024. The Data Size Converter shows the difference between the two.
Examples
- A 10 GB file at 100 Mbps: 10 GB = 80,000,000,000 bits. 80,000,000,000 ÷ 100,000,000 = 800 seconds (13 min 20 s).
- A 1 GB file at 8 Mbps: 1 GB = 8,000,000,000 bits. 8,000,000,000 ÷ 8,000,000 = 1,000 seconds (16 min 40 s).
- With an efficiency of 50%: a 100 Mbps connection is treated as 50 Mbps, so the 10 GB file takes 1,600 seconds (26 min 40 s).
Nominal speed and effective speed
The speed you enter is the nominal (theoretical) speed. The efficiency is the share of it that actually carries the contents of the file. The product of the two is the effective speed the calculation uses, shown in the result. The default is 100%, which is the theoretical best case.
In real transfers the speed is lower than the nominal speed for reasons such as:
- Part of the data is used for headers and other protocol overhead.
- The line is shared with other traffic, or a wireless signal (Wi-Fi) is weak.
- The sending or receiving device, or the server, limits the speed.
Because the efficiency varies a lot between environments, this tool does not suggest a typical figure. The simplest approach is to measure your real speed and enter it as the speed, with the efficiency at 100%.
Notes
- The size and the speed can have decimals (up to 12 digits before the decimal point and 6 after). Use a period as the decimal separator; commas are accepted only as thousands separators.
- The efficiency can have up to 2 decimal places.
- The time is rounded up to a whole second. A size of 0 gives 0 seconds.
- To find the size of a video from its length and bitrate, use the Video File Size Calculator.
Frequently asked questions
What is the difference between Mbps and MB/s?
Mbps is megabits per second and MB/s is megabytes per second. 1 MB/s = 8 Mbps.
My connection is 100 Mbps and the download shows about 12 MB/s. Is that normal?
Yes. 100 Mbps is 12.5 MB/s in theory, so a download of around 12 MB/s is within that figure. Overhead usually keeps the real speed a little below the theoretical value.
Are the upload and download speeds the same?
Not always. Many connections upload more slowly than they download, so use the matching speed for the direction you are transferring.
How do I calculate the time for several files?
Add the sizes together and enter the total.