Bits and bytes
A byte is eight bits. Plans are sold in megabits a second (Mbps), while browsers and download bars show megabytes a second (MB/s), so a 100 Mbps line peaks at 12.5 MB/s.
Data and bandwidth converter
Convert link speeds between bits and bytes, file sizes between decimal and binary units, and work out how long a download or a data bundle lasts. It runs in your browser: nothing you type is sent anywhere.
Speed
- bps
- 100,000,000
- Kbps
- 100,000
- Mbps
- 100
- Gbps
- 0.1
- B/s
- 12,500,000
- KB/s
- 12,500
- MB/s
- 12.5
- GB/s
- 0.0125
Size
- KB
- 1,000,000,000
- MB
- 1,000,000
- GB
- 1,000
- TB
- 1
- KiB
- 976,563,000
- MiB
- 953,674
- GiB
- 931.323
- TiB
- 0.909495
That is 1,000,000,000,000 bytes. Why an ISP's GB and Windows' GB differ: ISPs, drive makers and macOS count 1 GB as 1,000 MB. Windows counts in binary, 1 GiB is 1,024 MiB, but labels it GB, so a 1 TB drive shows as about 931 GB.
Download time
- Download time at full speed
- 13 min 20 s
- Data used per hour at that speed
- 4.5 GB
How long a data bundle lasts
- Runs out after, at full speed
- 2 h 13 min
- Data used per hour at that speed
- 4.5 GB
What each figure means
Why the numbers on a plan, a download bar and a drive never quite agree.
Download time is a floor
The time shown assumes the full line speed for the whole download. Protocol overhead, Wi-Fi and a busy server all make a real one take longer.
Data bundles
A bundle only runs out this fast while something downloads or streams flat out. Browsing and messaging use a fraction of the line most of the time.
Measure the speed you get
Plug in a real figure rather than the plan's: the speed test measures download and upload in one run.
Size an ISP's upstream
For the whole network rather than one line, the bandwidth calculator works out the capacity a subscriber base needs.