What this calculator does
Internet speed is sold in megabits per second (Mbps), but data usage, storage and download caps are almost always measured in gigabytes (GB). This mbps to GB calculator bridges the two: give it a connection speed and a length of time, and it works out the total data that moves in that window.
The conversion trips people up because megabits and megabytes are not the same unit, and the confusion compounds when megabytes are then converted to gigabytes. There are 8 megabits in a megabyte, and 1,024 megabytes in a gigabyte, so a "100 Mbps" connection is not doing 100 GB of work per second, or even close to it.
The formula
Convert the chosen duration to seconds. Multiply the speed in megabits per second by that number of seconds to get the total megabits transferred. Divide by 8 to convert megabits to megabytes, then by 1,024 to convert megabytes to gigabytes.
| Term | Meaning |
|---|---|
| Mbps | Megabits per second, the unit internet and network speeds are almost always advertised in. |
| MB | Megabytes, equal to 8 megabits. |
| GB | Gigabytes, equal to 1,024 megabytes. |
| Duration | The length of time the connection runs at the given speed, in seconds, minutes or hours. |
The inputs explained
| Field | What to enter |
|---|---|
| Connection speed (Mbps) | The connection speed as advertised or measured, in megabits per second. |
| Duration | How long the transfer runs for, in whatever unit is selected next to it. |
| Duration unit | The unit the duration above is entered in. |
When to use it
Checking a download cap or data allowance
A mobile or satellite plan with a fixed monthly data cap in GB can be checked against how much a given speed uses up over an hour of streaming or downloading.
Estimating file transfer volume for backups
Continuous transfers, such as an overnight backup running at a known network speed, can be sized in GB ahead of time to check they will fit available storage or bandwidth budgets.
Comparing plans by real-world data throughput
Two plans quoted in Mbps are easier to compare once translated into how much data each actually moves over the same period, such as a typical hour of use.
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 much data transfers in one hour at different speeds
The same one-hour window, run at a range of common connection speeds.
| Connection speed | Data transferred |
|---|---|
| 10 Mbps | 4.395 GB |
| 25 Mbps | 10.986 GB |
| 50 Mbps | 21.973 GB |
| 100 Mbps | 43.945 GB |
| 250 Mbps | 109.863 GB |
| 1000 Mbps | 439.453 GB |
How data transferred grows over time at 100 Mbps
A steady 100 Mbps connection, run for a range of durations.
| Duration (minutes) | Data transferred |
|---|---|
| 1 min | 0.732 GB |
| 5 min | 3.662 GB |
| 10 min | 7.324 GB |
| 30 min | 21.973 GB |
| 60 min | 43.945 GB |
| 120 min | 87.891 GB |
Questions
How many Mbps does it take to transfer 1 GB in a minute?
Rearranging the formula, 1 GB in 60 seconds needs roughly 137 Mbps (1 GB × 1,024 × 8 ÷ 60). Use the reverse mode on the mbps calculator if you want the speed needed for a specific file size and target time instead.
Why is my download slower than my advertised Mbps would suggest?
Advertised speeds are a maximum, not a guarantee, and real transfers are also capped by the server, network congestion, wifi overhead and how many devices share the connection at once. This calculator shows the theoretical maximum at the speed you enter, not what any single download will actually achieve.
Why divide by 8 and then by 1,024 rather than by 8,192 in one step?
Both give the same result, since 8 × 1,024 = 8,192. Splitting it into two steps just makes the megabyte figure visible along the way, which is useful for checking file sizes that are already quoted in MB.
Does this account for upload versus download speed?
No, it simply uses whatever speed figure you enter. Many connections have different upload and download speeds, so use the correct one for the direction of transfer you are estimating.
To go the other way and find the download time for a file of a known size, or the speed needed to hit a target time, see the Mbps download time calculator. To convert a speed figure between Mbps and Gbps directly, see the Mbps to Gbps converter.