How Fast Is Cable Internet?

Make sure you have the fastest speed possible

Cable remains one of the most popular types of high-speed internet access in the U.S., Canada, and other countries. Learn about cable internet speeds and how those speeds may vary depending on circumstances.

How Fast Is Cable Internet?

Rated connection speeds of cable internet connections typically range between 20 Mbps and 100 Mbps. In the early days of the internet, cable internet providers supported broadband network speeds as low as 512 Kbps (0.5 Mbps) for downloads. These speeds have increased over the years by a factor of 100 with improvements in internet network technology.

Actual data rates vary, depending on the provider and network conditions.

The Role of Cable Modems in Cable Internet Speed

Cable modem technology follows the industry standard Data Over Cable Service Interface Specification (DOCSIS). Older DOCSIS 2.0 cable modems supported download speeds up to about 38 Mbps and uploads up to about 27 Mbps. These modems worked well when cable internet providers offered service plans with 10 to 15 Mbps or lower data rates.

As cable technology has improved, the need for faster cable modems led to the introduction of DOCSIS 3.0, which increases modem performance compared to older DOCSIS versions. DOCSIS 3.0 (and newer 3.x) cable modems support connection speeds over 150 Mbps. Many cable internet providers sell plans for service that runs faster than 38 Mbps (typically, 50 Mbps for downloads).

Larger providers sell or rent DOCSIS 3.0 modems to ensure customers achieve the desired performance levels on home networks. Consumers can also buy modems if they prefer.

Things That Slow Down Cable Internet

Cable speed varies depending on usage patterns. A single cable line connects to many households, and the total available network bandwidth is shared among subscribers in that locality. If several of your neighbors access the internet simultaneously, it's possible that cable speeds for you (and them) will decrease during those times.

Otherwise, the causes of slowdowns are similar to those of DSL or other high-speed internet services:

  • Service glitches: Cable speed can suddenly drop if the service provider has technical difficulty with their network. Speeds should return to normal after a few minutes or hours (depending on the severity of the issue).
  • Bandwidth cap: Providers can throttle the performance of an individual subscriber's internet connection based on their terms of service. A customer who exceeds the monthly allowance of bandwidth, for example, may have their maximum download speed restricted to a lower value than normal.
  • Misconfigured or malfunctioning router: Home routers sit between home computers and the internet connection. If overloaded, overheated, or defective, a router can limit the speed at which devices stream or download data over the internet.
  • Slow connection to the router: Due to dynamic rate scaling, some Wi-Fi connections operate below 10 Mbps under certain conditions. No matter how fast the cable modem and its internet pipe, the speed of the internet for that device is limited by the slow Wi-Fi link.
  • Issues with devices: Old computers that lack sufficient processing power or memory cannot keep pace with a high-speed internet connection. Devices may also have apps that run in the background and consume these resources.

If your cable internet isn't performing as you expect, the service provider's connection may or may not be the cause. Perform some basic internet troubleshooting before contacting your service provider.

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