How to Test LAN Speed

It's often useful to test the speed of your local area network to ensure you're getting the amount of bandwidth that you need for various tasks. A LAN speed test can be useful in conjunction with an internet throughput test measuring how fast you can upload and download content from the internet at large or on its own to see how fast you can transfer files and data on your local network. You can find a variety of free apps to test the speed on your LAN.

A local area network is a set of computers and other devices like smart phones and printers connected within a relatively small space, such as an office, a university or a home. A LAN can include devices connected wirelessly, ones connected by wired connections or a mix of the two.

Today, many LANs are also connected to the internet, and some are primarily set up simply to send local traffic to the world at large. But it's often also useful to send data between computers on a LAN, whether you're connecting to a network-enabled monitor for a presentation, storing files on a local server or sending print jobs to a printer on your network.

If, thanks to heavy use, configuration issues or wireless interference, your LAN isn't particularly speedy, it can make these tasks slower. It can also interfere with your internet connection, since you'll usually send data through your LAN to a router or modem en route to the rest of the internet.

You can find downloadable tools and websites that will test your connection to the internet, as well as ones that can help you test connection speeds between two devices on your LAN. If you're diagnosing a network issue, it's often useful to do both to see where the problem lies.

When you check internal network speed, you'll usually want to measure the bandwidth and data transfer time between two computers on your network. Keep in mind that rates can vary between different sets of devices on the network.

One tool to use for measuring speed between two computers is iPerf, an open-source tool available for most modern computer operating systems, including Microsoft Windows, Apple macOS and Linux. Download and install iPerf on two computers on your network, and follow the instructions to set one up as an iPerf server and to have the other computer connect to it. You'll then get a report of the network speed between the two devices. If you can't connect from one computer to another, you may need to adjust your firewall settings.

Another free tool for this purpose is ping, which is also open-source and included with many operating systems. If you type "ping" in the command prompt on your computer, followed by an internet protocol address or domain name of another computer, such as "ping 192.168.0.1" or "ping www.example.com", your computer will send a message to the other asking it to reply. The program will display the amount of time it took to get a reply, with slower times being a sign of a faster connection. If you don't get a reply, you may need to adjust your firewall.

Another useful tool for understanding network speeds is traceroute, which works much like ping, but effectively asks for a reply from each router and computer between your computer and another one on the same network. It will allow you to understand what path messages take between two computers on your network and where connection bottlenecks may be. As with ping, type "traceroute" followed by the name or IP address of another computer to use the program. Read the manual for the version of traceroute on your computer to see what other options are available.

In addition to checking connection speeds within your network, you may want to check connection times and bandwidth between your computer and various servers on the internet.

You can use tools like traceroute and ping to connect to other online systems if your firewall rules allow it, and you can also use internet bandwidth testing programs to see how fast you can connect to other computers. Many internet providers offer speed-testing tools, and you can also use the well-known service called Speedtest from the tech company Ookla.

If your internal network appears speedy, but your internet connection is slow, consider contacting your internet provider for help.