DSL vs. Cable: Broadband Internet Speed Comparison

Choosing Between DSL and Cable High-Speed Internet

Illustration of a DSL and Cable store next to each other with posters extolling their services

 Lifewire / Jo Zixuan Xiuan

Both Digital Subscriber Line (DSL) and cable internet services far outclass, speed-wise, technologies like dial-up modems. Each approach offers a competing mix of trade-offs.

Bottom Line: Cable Is Faster in Theory

Cable-modem internet services on average promise higher levels of bandwidth than DSL internet services, and this bandwidth roughly translates to raw speed. However, while cable internet theoretically runs faster than DSL, several technical and business reasons can reduce or eliminate cable's speed advantage.

In terms of theoretical peak performance, cable modems run faster than DSL. Cable technology currently supports approximately 1000 Mbps of bandwidth (and some as high as 2000 Mbps) in many areas, whereas most forms of DSL reach speeds of less than 100 Mbps.

DSL vs. Cable: Real-World Speed

In practice, cable's speed advantage over DSL is much less than the theoretical numbers suggest. 

  • Cable modem services can slow down significantly if many people in your service area access the internet simultaneously.
  • Both cable modem and DSL performance vary from one minute to the next, depending on the pattern of use and traffic congestion on the internet.
  • DSL and cable internet providers sometimes implement speed caps that limit the bandwidth of their services.
  • Some home networks cannot match the speed of the internet connection, lowering performance.

About Speed Caps

Both cable and DSL service providers commonly employ bandwidth and speed caps for residential customers. Bandwidth caps place an artificial limit on the amount of data a customer can use in a month. Companies control the maximum speed a customer can achieve by monitoring their individual traffic flow and throttling network packets

Service providers offer several reasons for imposing bandwidth and speed caps:

  • Providers concerned about the capacity limits of their network may implement a cap so that they can accommodate more customers.
  • Providers may believe that the vast majority of customers do not actually need any more bandwidth than that allowed under the cap.
  • Providers may want to create a fair-and-equal distribution of bandwidth of customers. Without a cap, for example, some DSL subscribers would enjoy much higher bandwidth levels than others in the same neighborhood.
  • Some providers combat high bandwidth usage by certain customers by allotting a certain amount of data transfer each month. When the customer goes over that amount, the company slows down the data connection or charges an additional fee.
  • Providers that want to charge higher or lower rates for greater or lesser speeds do so through a modem setting. That way, the company can increase your speed when you upgrade your contract.

Tips for Improving Internet Speed

Whether you have high-speed cable or DSL service, you can improve connection speeds in several ways. If you aren't getting the speed you expect:

  • Cut back on the number of devices downloading, streaming, or gaming. You may have one or more computers, tablets, a PS4, Roku, Apple TV, or Slingbox all sharing your connection.
  • Security cams and other smart home devices also affect speed.
  • Wireless connections are slower than a wired connection. Connect your computer directly to the router with an Ethernet cable for the fastest speed. 
  • Update your router and modem to the most current specifications. A five-year-old modem probably can't handle the speeds your service providers. 
  • With wireless connections, your distance from the router makes a difference. The closer your device is to the router, the faster the wireless speed. 

Both cable high-speed internet and DSL services are available across the country, although in a few areas, only one is available. Both are popular and secure services. When you're shopping for a new service, ask about speed and bandwidth limits. You'll likely find that the company you deal with offers several different packages with increasingly faster connection speeds for increasingly higher prices. Your choice is guided by how you use the internet in your home. If you have a large family, and they are all streaming movies, the smallest package probably won't be sufficient. If you use the internet for email and occasional web surfing, it will be.