Why is my download slower than my plan speed?

Your plan speed is the maximum possible under ideal conditions. Real download speeds are reduced by network congestion, Wi-Fi signal quality, server throttling, the number of simultaneous connections and protocol overhead. A rough rule of thumb is to expect 60 to 80 percent of your advertised speed for typical downloads.

Why does this calculator use megabits not megabytes?

Internet connection speeds are measured in megabits per second (Mbps), while file sizes are usually shown in megabytes (MB). There are 8 bits in 1 byte, so a 25 Mbps connection transfers about 3.125 MB per second. This calculator handles the conversion automatically: enter the file size in MB and the speed in Mbps.

How long does a 1 GB file take to download?

At 25 Mbps, 1 GB (1024 MB) takes about 327 seconds, or roughly 5 minutes and 27 seconds. At 100 Mbps the same file takes around 82 seconds. Use this calculator to get the exact figure for your file size and connection speed.

Download Time Calculator

Whether you are deciding whether to start a large software download before bed, planning a video upload schedule, or comparing internet plans, knowing how long a file will take to transfer at a given speed is immediately useful. The relationship is straightforward in principle: divide the file size in bits by the connection speed in bits per second. In practice the unit conversion trips people up because file sizes are advertised in megabytes or gigabytes while broadband speeds are quoted in megabits per second, and there are 8 bits in every byte. A 25 Mbps connection transfers 25 million bits per second, which is about 3.125 megabytes per second, not 25. This calculator handles that conversion for you. Enter the file size in megabytes and your connection speed in Mbps, and you get the download time in hours, minutes and seconds, plus a comparison table showing how the same file would perform across a range of common connection speeds from 1 Mbps up to 1000 Mbps (1 Gbps). The comparison table is useful when weighing up whether a faster plan would make a meaningful difference for your typical file sizes. Results assume a sustained connection at the stated speed with no overhead or congestion. Real-world downloads are typically 20 to 40 percent slower than the advertised maximum.

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File size

Connection speed

Mbps

3m 44s

download time at your speed

Total seconds224

MB per second3.13 MB/s

File size in megabits5,600 Mb

Results assume sustained speed with no congestion or overhead. Real downloads are usually 60-80% of plan speed.

How it works

File size in megabytes is multiplied by 8 to convert to megabits, then divided by the connection speed in Mbps to get the total seconds. Hours are the integer division of seconds by 3600; remaining minutes are the integer division of the remainder by 60; remaining seconds are the modulo of 60. The comparison table runs the same calculation for a fixed set of reference speeds (1, 10, 25, 50, 100 and 1000 Mbps) using the file size you entered, so you can see the effect of upgrading or downgrading your plan.

Worked example

A 700 MB file at 25 Mbps: 700 MB times 8 equals 5,600 megabits. 5,600 divided by 25 equals 224 seconds. That is 3 minutes and 44 seconds. The transfer rate is 25 divided by 8 = 3.13 MB per second. These figures match the defaults pre-filled in the calculator above.

Related calculators

Bandwidth Calculator: total bandwidth for multiple simultaneous users or devices.
File Size Converter: convert between bytes, kilobytes, megabytes and gigabytes.
Typing Speed Calculator: measure words per minute and characters per minute.

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