Mbps to GB: how much data your speed moves
Divide Mbps by 8 to get megabytes per second. At full speed, 1 Mbps moves about 0.45 GB per hour, so 100 Mbps tops out near 45 GB per hour.
- Mbps measures how fast data can flow, while GB measures how much data moves.
- Plan speed is a ceiling, and your household almost never uses that much data.
- Check your real monthly use against the data cap in your own plan terms.
The quick answer: how Mbps becomes GB
Internet speed is sold in megabits per second (Mbps). Files and data caps are counted in gigabytes (GB). To connect the two, you need one rule: 8 bits make 1 byte.
- Divide your Mbps by 8 to get megabytes per second (MB/s).
- Multiply by 3,600 to get megabytes per hour.
- Divide by 1,000 to get gigabytes per hour.
For 1 Mbps, that works out to 0.125 MB per second, or 450 MB per hour. That is about 0.45 GB per hour if the line ran flat out.
Why bits and bytes trip everyone up
Mbps has a small b, which means megabits. MBps or MB/s has a capital B, which means megabytes. They look almost the same, but one byte is eight times bigger than one bit.
Plans are usually advertised in bits. File sizes, downloads and caps are usually shown in bytes. That is why a 100 Mbps plan doesn't download a 100 MB file in one second. It takes about eight seconds.
This guide uses decimal units, where 1 GB equals 1,000 MB. Some devices and operating systems count in binary units, so you may see small differences. That is normal.
Chart: what common plan speeds can move per hour
This chart shows the theoretical maximum. It assumes the connection runs at full plan speed for the whole hour, which almost never happens.
| Plan speed | MB per second | GB per hour at full speed |
|---|---|---|
| 25 Mbps | 3.125 | 11.25 |
| 100 Mbps | 12.5 | 45 |
| 300 Mbps | 37.5 | 135 |
| 500 Mbps | 62.5 | 225 |
| 1,000 Mbps | 125 | 450 |
How long a download takes at your speed
To estimate a download, convert the file to megabits (GB times 8,000), then divide by your speed. Or divide the file size by the GB per hour in the chart above.
For 50 GB at 300 Mbps: 50 GB is 400,000 megabits, and 400,000 divided by 300 is about 1,333 seconds. That is a little over 22 minutes at full speed.
| Plan speed | 5 GB file | 50 GB file |
|---|---|---|
| 25 Mbps | about 27 minutes | about 4.5 hours |
| 100 Mbps | about 7 minutes | about 67 minutes |
| 300 Mbps | about 2 minutes | about 22 minutes |
| 500 Mbps | about 1.3 minutes | about 13 minutes |
| 1,000 Mbps | about 40 seconds | about 7 minutes |
Treat these as ideal-case times. Real downloads usually take longer.
Speed is a ceiling, not what you use
Speed tells you how fast data can move. Usage tells you how much data actually moved. A fast plan doesn't use more data on its own. It only lets a big download finish sooner.
Here are commonly seen ranges for everyday activity. They vary by service and settings.
- Streaming in standard quality: often under 1 GB per hour.
- Streaming in HD: often about 1 to 3 GB per hour.
- Streaming in 4K: often about 7 to 12 GB per hour.
- Video calls: often about 0.5 to 2 GB per hour.
- Large updates and game downloads: from a few GB to tens of GB each.
Compare that with the 45 GB per hour ceiling of a 100 Mbps plan. Even a household streaming on several screens uses a small share of it. Speed matters most when many devices run at once or when you grab very large files. For help judging what you need, see what is a good internet speed.
Why your real numbers come in lower
Real-world throughput is usually below the plan speed. Several things cause this:
- Protocol overhead. Some of the traffic is addressing and error checking, not your file.
- Wi-Fi conditions. Distance, walls and crowded channels slow the signal.
- Device limits. Older phones, laptops and network ports may not handle top speeds.
- The other end. A server may send data slower than your line can take it.
The gap changes from home to home and hour to hour. A speed test shows what you get at that moment. Our guide on how to test your internet speed explains how to get a fair reading.
How to check your usage against a data cap
Not every plan has a cap, and cap sizes differ by plan and connection type. Read your own plan terms and broadband label instead of assuming a number. For more background, read internet data caps explained.
To compare your use with a cap, follow these steps:
- Find your monthly usage in your provider account or router settings, if offered.
- Add up your own estimate from hours of streaming, calls and updates using the ranges above.
- Compare both numbers with the cap in your plan terms.
Questions to ask your provider:
- Does my plan have a monthly data cap, and what is the exact amount?
- What happens if I go over it, and are there overage charges or slower speeds?
- How do you measure usage, and does it include both downloads and uploads?
- Can I see my usage during the month?
Common questions
How many GB is 100 Mbps per hour?
At full speed, 100 Mbps moves about 45 GB per hour. Real use is almost always lower because of overhead, Wi-Fi and device limits.
How do you convert Mbps to GB per month?
Multiply the Mbps by 0.45 to get GB per hour, then by the hours in the month. For a 30-day month that's about 324 GB per Mbps, so 100 Mbps could move roughly 32,400 GB if it ran flat out nonstop. Your actual use will be far smaller.
What is the difference between Mbps and MBps?
Mbps means megabits per second and is how plan speeds are usually listed. MBps means megabytes per second and is closer to how files are sized. One byte is 8 bits, so divide Mbps by 8 to get MBps.
How long does it take to download 50 GB at 300 Mbps?
About 22 minutes at full speed. 50 GB is 400,000 megabits, and dividing by 300 gives roughly 1,333 seconds. Real downloads often take somewhat longer.