Understanding Bandwidth & Data Transfer
Bandwidth is the maximum rate of data transfer across a given path. It is commonly measured in bits per second (bps). In consumer internet plans, bandwidth is often marketed in Megabits per second (Mbps) or Gigabits per second (Gbps).
A common point of confusion is the difference between a "bit" and a "byte". File sizes on your computer are typically measured in Bytes (e.g., Megabytes, Gigabytes), while network speeds are measured in bits. Since there are 8 bits in 1 byte, a 100 Mbps (Megabits per second) connection will optimally download at 12.5 MB/s (Megabytes per second).
Bits vs. Bytes
The capitalization of the letter 'b' is crucial in networking:
- b (lowercase): stands for "bits". (e.g., Mbps = Megabits per second)
- B (uppercase): stands for "Bytes". (e.g., MB/s = Megabytes per second)
- 1 Byte = 8 bits
Key Terms
- Download SpeedThe rate at which data is transferred from the internet to your device.
- Upload SpeedThe rate at which data is transferred from your device to the internet.
- OverheadNetwork protocols (like TCP/IP) require extra data to ensure successful transmission, typically adding 5-10% to the total file size.
Common File Sizes & Estimated Download Times (at 100 Mbps)
| Media Type | Average Size | Time at 100 Mbps |
|---|---|---|
| MP3 Audio Track | 5 MB | 0.4 Seconds |
| High-Res Photo | 15 MB | 1.2 Seconds |
| Software Update | 500 MB | 40 Seconds |
| HD Movie (1080p) | 4 GB | 5.3 Minutes |
| 4K Ultra HD Movie | 20 GB | 26.6 Minutes |
| Modern AAA Video Game | 80 GB | 1.8 Hours |