Definition
Bandwidth is the capacity of a network link — how much data can move through it per unit of time. It is commonly measured in megabits per second (Mbps) or gigabits per second (Gbps). Bandwidth is often confused with speed but is not identical: bandwidth is the size of the pipe, throughput is how much actually flows through it under real conditions, and latency is how long a single packet takes to travel from one end to the other.
How a VPN Affects Bandwidth
A VPN cannot give you more bandwidth than your underlying internet connection provides — it can only equal it or, more commonly, reduce it. Encryption and decryption consume CPU cycles, packet headers add overhead (40 to 100 bytes per packet), and routing through an intermediate server adds physical distance. A modern VPN running WireGuard on capable hardware loses very little — often less than 10 percent. An older OpenVPN setup over TCP on a distant server can lose 50 percent or more.
Bandwidth Caps
Some providers, especially on free tiers, impose explicit bandwidth caps — for example, 10 GB per month — after which the connection is throttled or cut. Reputable paid providers advertise unlimited bandwidth, though their terms typically reserve the right to throttle abusive traffic. Note that a VPN can also help recover bandwidth: if your ISP throttles specific services like video streaming or torrenting, a VPN hides the protocol from them and may restore full speed.