Download Time Calculator

How long will this download take?

Result

How it is calculated

The tool converts everything to bits and divides: seconds = size × 8 / speed. File size is taken in decimal units (1 MB = 1,000,000 bytes, 1 GB = 10⁹ bytes, 1 TB = 10¹² bytes) and multiplied by 8 to get bits. Speed units are Mbps (megabits per second, 10⁶ bits/s), Gbps (10⁹ bits/s) or MBps (megabytes per second, counted as 8 × 10⁶ bits/s). The seconds are then shown as hours, minutes and seconds. The result is the ideal time at a constant full speed: real transfers are slower because of protocol overhead, shared connections, server limits and Wi-Fi quality. Size and speed must be above zero.

Worked example

A 4.5 GB game download on a 100 Mbps connection. Size in bits: 4.5 × 10⁹ × 8 = 36 × 10⁹ bits. Speed: 100 × 10⁶ bits per second. Time = 36 × 10⁹ / 100 × 10⁶ = 360 seconds, which the tool shows as 6 min. If you mistakenly read 100 as megabytes per second, you would expect about 45 seconds, an eightfold difference.

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Common mistakes

  • Mixing up megabits (Mbps, used for internet plans) and megabytes (MBps, used for file sizes); one byte is 8 bits, so the answer differs by a factor of 8.
  • Choosing the wrong unit in the dropdown, such as TB instead of GB.
  • Expecting to reach the advertised speed; real throughput is often lower than the plan's maximum.
  • Forgetting that the speed is shared between all devices on the network.
  • Using binary sizes (GiB) and expecting an exact match, since the tool uses decimal GB.

About this calculator

This calculator divides a file's size by your connection speed to estimate how long a download or upload will take, converting between the units files are measured in (megabytes, gigabytes) and the units internet speeds are advertised in (megabits, gigabits per second) — a distinction that trips a lot of people up since 1 byte equals 8 bits.

It's used to sanity-check an ISP's advertised speed against real-world transfer times, to plan around a large download like a game update, video file or OS image before starting it, and by IT staff estimating how long a backup, file transfer or software deployment will take over a given network link.

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Comments (1)

  • Editorial team

    File managers often report sizes in binary units, where one gigabyte is 1,073,741,824 bytes, while this tool counts a gigabyte as 1,000,000,000 bytes. For a large file that makes the real transfer about 7 percent longer than shown, before any network overhead. When estimating an upload, enter your plan's upload speed, which is frequently much lower than the download figure. Which speed unit or file size would you like to see added?

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