How fast is a 10/100/1000 switch?

A 10/100/1000 switch is as fast as 1000 Mbps (1 Gbps).

The numbers 10, 100, and 1000 refer to the maximum network speed a connected device can negotiate with the switch:

10 Mbps = 10 Megabits per second
100 Mbps = 100 Megabits per second
1000 Mbps = 1 Gigabit per second

Think of it like a road that can change its width depending on the vehicle using it.

An old printer might only need a narrow one-lane road (10 Mbps).
An older PC might use a two-lane road (100 Mbps).
A modern PC, NAS, or server can use the full highway (1000 Mbps).

The switch automatically picks the fastest speed that both devices support.

For example:

PC ─── 1 Gbps ─── Switch ─── 1 Gbps ─── NAS

The PC can transfer files to the NAS at up to 1 Gbps because both ends support Gigabit Ethernet.

One common misunderstanding is that the switch shares 1 Gbps across all ports. It does not.

Think of a 24-port Gigabit switch as 24 separate roads, not one road split into 24 lanes. If multiple devices are talking at the same time, each port can still run at up to 1 Gbps, provided the switch has enough switching capacity.

In file transfer terms, 1 Gbps equals about 125 MB/s (Megabytes per second) under ideal conditions. Real-world speeds are usually a bit lower due to protocol overhead and storage limitations.