Common Internet Speed Terminology Explained for Non-Techies
Every term a provider, router or support agent will use, explained in one sentence each — and why bandwidth is not speed.
Internet speed has accumulated a vocabulary that sounds interchangeable but is not. Here is every term you will meet on a bill, a router page or a support call, in plain English.
The units
Bit (b)
The smallest unit of digital data — a single 1 or 0. Networks are measured in bits.
Byte (B)
Eight bits. Files are measured in bytes. The capital letter is the entire difference — see bits vs bytes explained.
Mbps (megabits per second)
The unit ISPs advertise. Also written Mbit/s or Mb/s. One thousand of these is a Gbps.
MB/s (megabytes per second)
The unit your computer shows during a download. Always one eighth of the Mbps figure.
MB/s = Mbps ÷ 8Kbps and Gbps
A thousandth and a thousand times a megabit respectively. 1 Gbps = 1,000 Mbps = 125 MB/s.
Speed, bandwidth and throughput
These three get used interchangeably and mean genuinely different things.
- Bandwidth is capacity — the maximum the connection could carry. The width of the pipe.
- Throughput is what you actually achieve, after overhead and congestion. The water actually flowing.
- Speed is a loose everyday word usually meaning throughput, though marketing uses it for bandwidth.
Your plan sells you bandwidth. Your speed test measures throughput. They are never quite the same number.
The timing terms
Latency
How long one packet takes to travel to a server and back, in milliseconds. Completely independent of bandwidth — a satellite link can have huge bandwidth and terrible latency.
Ping
In everyday use, a synonym for latency. Strictly it is the diagnostic tool that measures it. Under 20 ms is excellent; over 100 ms is noticeable in games and calls.
Jitter
How much latency varies between packets. Low jitter matters more than low latency for voice and video: a steady 40 ms beats one swinging between 10 and 90 ms.
Packet loss
The percentage of packets that never arrive and must be resent. Anything above about 1% causes audible glitches in calls and rubber-banding in games.
The plan and network terms
Asymmetric
Download and upload speeds differ, usually by a lot. Standard on cable, DSL and 5G — see upload vs download speed.
Symmetric
Download and upload are equal. Typical of fibre.
Contention ratio
How many households share the same local capacity. High contention is why cable slows at 8pm.
"Up to"
A ceiling, not a promise. The advertised figure is the best case under ideal conditions.
Throttling
Deliberate speed reduction — after a data cap, for particular traffic types, or during congestion.
Data cap / fair use policy
A monthly volume limit. At 125 MB/s, a 1 TB cap is about two hours and fifteen minutes of continuous downloading.
Overhead
Bandwidth consumed by protocol headers rather than your data. Typically 5-10% of any transfer.
The hardware terms
| Term | Means |
|---|---|
| Router | Directs traffic between your devices and the internet |
| Modem | Converts the ISP's signal into Ethernet; often built into the router |
| Ethernet | Wired network connection — faster and steadier than Wi-Fi |
| Wi-Fi 5 / 6 / 6E / 7 | Successive wireless standards; each faster and better in crowds |
| 2.4 GHz | Long range, slow, congested |
| 5 GHz | Shorter range, much faster — what you want for most devices |
| Mesh | Multiple access points sharing one network name for coverage |
| QoS | Router feature prioritising interactive traffic over bulk transfers |
Three conversions worth memorising
- Mbps to MB/s: divide by 8. 500 Mbps = 62.5 MB/s.
- MB/s to Mbps: multiply by 8. 12 MB/s = 96 Mbps.
- Gbps to MB/s: multiply by 125. 2 Gbps = 250 MB/s.