Mbps is a rate
Megabits per second, written Mbps, measures a data transfer rate. File sizes are often written in megabytes, or MB. Bits and bytes differ: one byte contains eight bits.
Bandwidth and throughput
Bandwidth describes capacity. Throughput is the rate achieved during an actual transfer. A service’s advertised rate is not a promise that every device and every website will deliver that rate at all times.
Latency describes delay
Latency is time, usually measured in milliseconds. A common measurement is round-trip delay: the time for a request to reach a destination and a response to return. A connection can have high capacity while still showing noticeable delay.
Download and upload
Downloading brings data to your device, such as receiving a video. Uploading sends data from it, such as sharing a file. A video call uses both directions. Different internet plans may provide different download and upload rates.
Why a single result is limited
A measurement reflects a particular device, connection path, destination, and moment. It cannot, by itself, establish the cause of an issue. This lesson explains the vocabulary; it does not perform a connection test or diagnose a service.
Check your understanding: Does more Mbps always mean less delay?
No. Capacity and delay are different measurements. A larger transfer rate does not guarantee a shorter round-trip time.
Further reading
Cloudflare: latency, bandwidth, and throughput.
Jitter and packet loss
Jitter describes variation in delay. If data arrives at uneven intervals, real-time audio or video can be harder to deliver smoothly. Packet loss means that some units of transmitted data do not reach their destination. Applications handle this differently, depending on how they communicate.
Shared use in a household
A home’s internet connection can carry traffic from several devices at once. A large file transfer, a cloud backup, and a video call may compete for available capacity. That is why a plan’s transfer rate should not be read as a dedicated rate guaranteed to every device simultaneously.
Compare like with like
When reading measurement results, notice the units, direction, device, connection type, and time. A Wi-Fi measurement from a phone and an Ethernet measurement from a laptop describe different paths. Neither is automatically a complete assessment of the household’s service.