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Internet speed vs download speed
Why a 100 Mbps plan downloads at 12.5 MB/s, how long a file should take, and how much monthly traffic a connection can carry.
Download Time Calculator
Enter a file size and your connection speed to see how long the download will take. The download time calculator converts between Mbps and MB/s for you.
Runs in your browser. Your data is not uploaded.
The same file at common speeds
| Speed | MB/s | Download time |
|---|
How to use the Download Time Calculator
- Enter the File size and pick its unit, such as GB or GiB.
- Enter your Speed and its unit. Internet plans are usually in Mbps. Tick Include network overhead for a more realistic estimate.
- Press Calculate. The time appears in hours, minutes, and seconds, with a table of the same file at other common speeds.
How it works
seconds = (sizeBytes × 8) ÷ (speedBitsPerSecond × (1 − overhead))
- sizeBytes: the file size in bytes. 1 GB is 10^9 bytes, and 1 GiB is 2^30 bytes.
- × 8: turns bytes into bits, because speeds are measured in bits
- speedBitsPerSecond: the speed in bits per second. 1 Mbps is 10^6 bits per second, and 1 MB/s is 8 × 10^6.
- overhead: the share of the speed lost to protocols and the network, 0 by default or 10% when turned on, adjustable up to 50%
Examples
- 5 GB at 100 Mbps = 6 min 40 s (400 seconds). With 10% overhead: 7 min 24 s.
- 50 GB at 25 Mbps = 4 h 26 min 40 s.
- 1 GB at 100 Mbps = 80 s.
5 GB at 100 Mbps
The first example in the calculator: a 5 GB file at 100 Mbps takes 6 min 40 s, or 400 seconds, at 12.5 MB/s with no overhead. This example is one of the automated tests for the tool, so a code change that gives a different answer fails the test run.
Download times at 100 Mbps
| File size | Time at 100 Mbps |
|---|---|
| 100 MB | 8 s |
| 1 GB | 1 min 20 s |
| 5 GB | 6 min 40 s |
| 50 GB | 1 h 6 min 40 s |
| 100 GB | 2 h 13 min 20 s |
These are ideal times. Doubling the speed halves the time, so at 200 Mbps each figure is cut in half, and at 50 Mbps it doubles.
Limitations
- Real downloads vary with server limits, Wi-Fi, congestion, and peak versus sustained speed. The result is a best-case estimate.
- A speed of 0 gives an error.
- Results longer than 30 days are also shown in days.
- The calculator assumes a constant speed for the whole download.
Sources
- Prefixes for binary multiples, NIST. Why 1 GB is 10^9 bytes and 1 GiB is 2^30 bytes.
Frequently asked questions
Why is my download slower than the calculator says?
Advertised speeds are maximums. Protocol overhead, Wi-Fi quality, busy networks, and server limits all reduce the real speed. Turn on overhead for a more realistic estimate.
What is the difference between Mbps and MB/s?
Mbps is megabits per second, and MB/s is megabytes per second. One byte is 8 bits, so 100 Mbps is 12.5 MB/s.
How long does 1 GB take at 100 Mbps?
About 80 seconds in ideal conditions: 1 GB is 8,000 megabits, and 8,000 ÷ 100 = 80.
Related tools
Often used together with Download Time Calculator.
Byte ConverterConverters
Converts any data-size unit to all other units at once.
Mbps to MB/s Converter
Converts internet speeds between Mbps, MB/s, and other units.
Bandwidth Calculator
Speed for a data volume, website bandwidth, and GB/month vs Mbps.