What this calculator does
Mbps measures how many megabits a connection can move each second, but file sizes are almost always shown in megabytes or gigabytes, which are eight times larger in bits. That mismatch is the usual reason an "estimated time remaining" figure looks slower than the advertised connection speed suggests it should be.
This mbps calculator converts a file size and a connection speed into a download or upload time, or works the other way, telling you the Mbps speed needed to move a given file in a target time. Both directions account for the megabyte-to-megabit conversion automatically.
The formula
A file of a given size in gigabytes is first converted to megabits by multiplying by 1024 (GB to MB) and then by 8 (MB to Mb, since one byte is eight bits). Dividing that megabit figure by the connection speed in Mbps gives the time in seconds. Working from a target time instead, the same megabit figure is divided by the time in seconds to give the Mbps speed required.
| Term | Meaning |
|---|---|
| Mbps | Megabits per second, the standard unit for internet connection speed, advertised by ISPs and shown in speed tests. |
| MB vs Mb | A megabyte (MB) is 8 megabits (Mb). File sizes are shown in megabytes or gigabytes; connection speeds are shown in megabits per second, so the two need converting before they can be compared directly. |
| Download time | File size in megabits divided by connection speed in Mbps, giving the time in seconds a transfer takes at that speed with no other traffic competing for the connection. |
The inputs explained
| Field | What to enter |
|---|---|
| Solve for | Whether to solve for the download time given a speed, or for the speed needed given a target time. |
| File size (GB) | The size of the file being downloaded or uploaded, in gigabytes. |
| Connection speed (Mbps) | The connection speed, in Mbps, used when solving for download time. |
| Target time (minutes) | The target time to finish the transfer, in minutes, used when solving for speed needed. |
When to use it
Estimating how long a large download will take
Entering a file size and an advertised or measured connection speed gives a realistic download time, useful before starting a large game, video or backup download over a mobile hotspot or a slower connection.
Checking whether a plan is fast enough for a deadline
Working from a target time backwards shows the minimum Mbps speed needed, useful when deciding whether an internet plan upgrade is worth it before a large upload is due.
Explaining why an advertised speed feels slower than expected
Because Mbps counts bits and file sizes count bytes, a "100 Mbps" connection moves at most 12.5 megabytes per second in practice, a distinction that explains a lot of "why is my internet so slow" confusion.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How long does a download take at 100 Mbps, by file size?
A range of file sizes, each converted to a download time at a fixed 100 Mbps connection speed.
| File size | Download time | In seconds |
|---|---|---|
| 1 GB | 1.37 min | 82 s |
| 2 GB | 2.73 min | 164 s |
| 5 GB | 6.83 min | 410 s |
| 10 GB | 13.65 min | 819 s |
| 25 GB | 34.13 min | 2,048 s |
| 50 GB | 1.14 h | 4,096 s |
What Mbps speed is needed to download a 5 GB file in a given time?
A range of target times, each converted to the Mbps speed required to finish downloading a fixed 5 GB file within that time.
| Target time | Speed needed | In Gbps |
|---|---|---|
| 1 min | 682.67 Mbps | 0.6827 Gbps |
| 5 min | 136.53 Mbps | 0.1365 Gbps |
| 10 min | 68.27 Mbps | 0.0683 Gbps |
| 15 min | 45.51 Mbps | 0.0455 Gbps |
| 30 min | 22.76 Mbps | 0.0228 Gbps |
| 60 min | 11.38 Mbps | 0.0114 Gbps |
Questions
How do I calculate Mbps to download time?
Convert the file size to megabits (gigabytes × 1024 × 8), then divide by the Mbps speed to get the time in seconds. A 5 GB file at 100 Mbps takes 5 × 1024 × 8 ÷ 100 = 409.6 seconds, about 6.8 minutes.
Is 100 Mbps fast?
It is a solidly fast home connection, enough for 4K streaming on several devices at once and downloads at up to about 12.5 megabytes per second. Fibre and cable plans now commonly advertise 500 Mbps to 1 Gbps for heavier or multi-user households.
Why does my download speed not match my Mbps plan?
The advertised Mbps figure is a maximum, shared across every device on the network and subject to the download server's own speed, Wi-Fi signal strength and network congestion; actual throughput is often noticeably lower.
How many MB is 1 Mbps?
One Mbps moves one megabit per second, which is 0.125 megabytes per second, since a megabyte is 8 megabits. A 100 Mbps connection therefore moves at most 12.5 MB per second.
For a decimal-hours to hours-and-minutes conversion instead of a transfer estimate, see the minutes to hours calculator. For general duration arithmetic, see the time duration calculator.