What is Latency and Why Should I Care?
Latency is most often (but not always) responsible for what internet users call “lag,” and you should care because high-latency internet is beyond frustrating. Unfortunately, latency is rarely discussed or advertised by companies selling internet.
Latency is the time it takes for your computer's internet to contact a server. It is most often measured in milliseconds (ms), which are 1/1000ths of a second. When talking about internet speeds, however, providers almost always advertise their bandwidth, which is measured in megabits (Mbps). High latency and low bandwidth can both cause “slow internet,” but high latency will be more consistently noticeable. To understand the difference between the two, think about turning your kitchen faucet on as an analogy for loading a web page. Latency would be the time it takes for water to start coming out. Bandwidth is most similar to how much water comes out. If filling up a glass is compared to loading a website, both high latency and low flow (bandwidth) would cause a delay, but in a different way. It is technically possible to have a “gig” connection that feels slow if the latency were high. Using the water analogy, it would be like having an industrial sized pipe and faucet that took several seconds to turn on, but filled the glass instantly once it started flowing.
What types of service have better latency?
In general, fiber internet will have the lowest latency, followed by cable. Both should be below 100ms. DSL may have slightly higher latency, but it will generally be hard to notice while browsing with response times under 150ms. Satellite internet tends to have the highest and most noticeable latency, with average latencies around 700ms. Latency varies the most when it comes to wireless internet. Some users pointing dishes (e.g. microwave receivers) at far-away towers may have very high latency, while other users may experience fiber-like latency. It all depends on the provider and the technology being used. In general LTE and 5G wireless providers will have lower latency than other types of wireless providers, and may even compete with fiber for ultra-low latency. Other wireless providers may have latency just slightly better than satellite.
How do you know whether high latency or low bandwidth makes your internet slow?
First, you can run a speed test to determine your internet's speed and latency. Some speed tests measure both download latency and upload latency in milliseconds. Anything under 25ms is considered excellent, and under 75ms is good. The table below shows how high latency and low bandwidth might be felt differently in different use cases:
Activity |
High Latency Only |
Low Bandwidth Only |
Gaming |
Jumpy performance, delays between a click and the action, and being kicked by servers |
Long times to download and patch games. Generally gaming works fine, but players may load slower |
Video and voice calls, e.g. Zoom |
Users have delays in receiving sound, and usually delays in having their voice received. The result is usually a delayed conversation where it's hard to avoid speaking over one another |
Grainy video, poor voice quality |
Browsing: Instagram or an image-heavy website |
Images take a long time to start loading, but a full page of images could load quickly once the first appears |
The first image loads quickly, with one image loading at a slow, steady pace after that |
Browsing: Google |
There is a noticeable delay between your search and the results |
There is no noticeable delay in getting results |
Downloading a large file i.e. a videocast or long podcast |
The download takes a second to start, but downloads quickly |
The download starts instantly, but takes a long time to finish |
Streaming |
Videos take a long time to start, and buffering may be common |
Video quality is grainy, and buffering may be common |
Regarding video and voice calls, some users have found that they can see others' videos clearly and hear others, but other people cannot hear them, or that their video hangs. This is an indication of a high download speed, which is usually the only number advertised, and a low upload speed. So you can see that diagnosing internet problems can be difficult, but between a speed test and the symptoms you experience this should help you narrow it down.
What is causing my high latency?
High latency can be caused by any of the following:
- Being connected to WiFi instead of through a wired connection, i.e. to your router. The further you are and the weaker your WiFi signal, the greater your latency.
- Using very old hardware. Some modems and routers will be faster than others, but this is mostly a problem of the past. The difference between a “fast” modem/router combo and a “slow” modem/router combo with modern hardware would be less than 10ms, and probably less than 5ms.
- Having excessively slow firewall technology or traffic management hardware/software. This is rare for homes, and most users who know how to set up firewalls would also know how to diagnose latency issues.
- The technology and infrastructure of your internet provider (most common)
What can I do to improve my latency?
- Plug in to your router. If there's no room in the router, you can get an “unmanaged switch” that allows you to plug in multiple devices
- Make sure you're using hardware made in the last 6 or so years. Note: It's generally cheaper to buy your own modem rather than rent it from your ISP.
- Speak with your tech support if things are slow at work.
- Switch from your internet providers DSL or wireless service to fiber
- Switch internet providers
For most people, noticeably bad latency is an internet provider issue, and the only solution is to switch internet providers. Click the link below to see what's available.
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