What is an Internet Speed Test?

A speed test is the best way to check your internet speed. Internet service providers (ISPs) promise "up to" a certain speed under optimal conditions, but a speed test shows you exactly how fast or slow your connection actually is.

What is a Speed Test?

An internet speed test is the best way to determine your current connection speed. The service you connect to varies depending on the plan you choose, local congestion, throttling rules, and more. Typically, providers limit both download and upload speeds according to your connection.

The trick is that internet service providers almost always include the phrase "up to." If they promise "up to 30Mbps" speed and you consistently get only 28Mbps, you can say the provider is keeping their promise. However, if you're seeing 10Mbps, you're not getting what you paid for, so now you need to contact your service provider.

Speed tests measure ping and download and upload speeds. Measuring the last two is important because most ISPs promise download and upload speeds separately. Typically, download speed is noticeably prominent, but if you look at the details, ISPs typically set slower upload speeds for each tier. For example, a local ISP may offer a plan with 50Mbps download speed but only 5Mbps upload speed.

How Does an Internet Speed Test Work?

You can easily test your speed with TestSpeed.it.
After selecting a server, ping, download, and upload tests are performed.
When you start a speed test, more than one thing happens. The TestSpeed.it Speed Test sends a simple signal (ping) to the server, which responds. The test measures this round trip in milliseconds.

Once the ping is complete, the download test begins. The client opens several connections to the server and attempts to download small pieces of data. At this point, two things are measured: how long it takes to capture the data and the amount of network resources used.

When the client detects there's spare capacity, it opens more connections to the server and downloads more data.

Imagine your internet service as a speed-limited highway. Opening additional links is like adding lanes to a highway. The speed limit hasn't changed, but more vehicles can traverse the same area faster. So the 50th vehicle arrives earlier from a 2-lane road now using a 4-lane highway.

Once the client confirms it has the right connections to test the internet service, it downloads additional data chunks, measures how much was downloaded in the allocated time, and provides the download speed.

Next is the load test. It's actually the same process as the download test, but in reverse. Instead of the client getting data from the server to your computer, it uploads data from your computer to the server.

Are Internet Speed Tests Accurate?

Speed tests sound simple, but accurately measuring connection speed can be much more difficult than you think. Several factors can affect a speed test.

Consider the first step of the process: selecting a test server. Often, the closest server may be incredibly close or even in the same city. This proximity is optimal, so there's not enough data to travel. Companies know that proximity makes a difference, so some like Netflix use content delivery networks to bring data closer.

However, not all of the internet is close to you. Most of it is on remote computers, sometimes across the country or in another country. So while a speed test may show very fast throughput, if the server hosting the data is far away, your program download speed may be very slow. In this scenario, results may reflect performance faster than actual usage.

When testing with TestSpeed.it, you may see different speed results. Your service provider may also offer a speed test service. However, you shouldn't rely on speed tests created by your ISP. Provider tests are typically optimized for ideal conditions using nearby servers that remain on the same ISP network being tested.