What's the difference between bandwidth and throughput?

Bandwidth and throughput are two metrics that measure how much data can move through a network. Although they are frequently used synonymously, bandwidth refers to a network's maximum theoretical capacity for data transfer, while throughput indicates the actual amount of data that is successfully transmitted in practice.

When shopping for an internet plan, the two terms you’ll likely hear the most are bandwidth and speed. These are theoretical terms, however, and your network’s throughput is a more realistic measure of its performance even though ISPs don’t use this term nearly as often, and you may not have even heard of it before. Understanding it and its differences with bandwidth can help you pick the right internet plan for you and better evaluate your internet speed.

So what are a network’s bandwidth and throughput, and what’s the difference between them?

What is network bandwidth?

Bandwidth is a network’s capacity. It’s the maximum volume of information that a wired or wireless channel can theoretically ferry from one point to another in a given period of time. Each network has its own bandwidth, established at the time of setting up that network. It’s measured in bits of information. So when you see an internet service provider advertise a 1 Gbps connection, it means every second it can carry a maximum of one gigabit of data from the source to the destination.

A network can only accomplish its bandwidth in ideal, controlled environments. In reality, a network is hindered by a host of factors that can slow it down and take a hit on its efficiency. There could be a leak in the connection, the distance between the sender and the recipient may be too long to quickly exchange requests, or the quality of routers could be poor. Therefore, you’re unlikely to ever reach the bandwidth your ISP promised when you purchased its internet plan.

More importantly, the bandwidth is a finite and fixed resource. It is shared across all members of a network and how much each member is assigned is based on their internet activities. For example, say one person on your home internet is downloading a high-res movie online and another is on a group video call. The network may allocate most of its capacity to the former, causing the latter to face interruptions and stuttering feeds.

In such congested scenarios, the only way to ensure each participant has a smooth internet experience is to upgrade to a plan with more bandwidth. The higher the bandwidth, the more data a connection can transfer in an instance.

To further illustrate this, let’s take a water pipe. There’s a certain volume of water that can pass through it at a time, and if you want it to carry more, your sole option is to switch to a pipe with a wider diameter. Here, the water is your online data, and the pipe’s diameter and volume are the bandwidth.

What is network throughput?

If the pipe’s volume in the aforementioned analogy is the bandwidth, the amount of water passing through it at any given time is the throughput. Bandwidth is a theoretical metric that stays fixed no matter what. Throughput, on the other hand, is its practical equivalent. It refers to how much actual data a network is successfully transferring at any given moment.

Throughput indicates a connection’s performance and how significantly its bandwidth is affected by issues like packet loss and congestion. Its value is never more than the bandwidth and is only equal when the network is at its peak performance.

Similar to bandwidth, the throughput of a network is equated in terms of bit rates. In a network that has a 1 Gbps bandwidth and a 250 Mbps throughput, we can say that the network is performing at a quarter of its max capacity. The average quantity of data that moves from the server where a website is stored to your browser in a period of time is the network’s throughput.

A connection’s throughput varies constantly and is influenced by a wide variety of factors. When there are too many people on a network requesting large files, for instance, some may have to wait for the channels to be free, and packets of data will take longer to complete their journeys, decreasing the overall throughput. Similarly, if the distance between the server and the device is farther than usual (which is also known as “high latency”), the network will take more time to deliver files, further diminishing the throughput.

What's the difference between bandwidth and throughput?

Bandwidth defines the maximum amount of data that can travel in a network, while throughput measures the actual amount of data that’s traveling through that network at any given time.

Think of bandwidth as a highway designed to accommodate and move no more than 300 cars from origin to destination in an hour. But an accident on one afternoon blocks the traffic, and only 200 cars are able to cross it. Later in the evening, one of the lanes becomes unusable due to potholes and overuse, and now just 150 cars are passing in an hour.

The 200 and 150 figures are the highway’s real-time throughput, and the accident and broken lane are like the many bottlenecks networks face, such as packet loss and congestion, which make it impossible to realistically achieve the max bandwidth.

As we observed in the highway analogy, throughput is a variable metric while bandwidth is constant. You don’t have any control over your internet’s bandwidth except to switch to a better plan with a higher data capacity. But to boost your network’s throughput, you can consider a host of steps yourself like upgrading your internet equipment, switching from a wireless connection to a wired one, or removing some devices from the connection.

How do bandwidth and throughput affect your internet speed?

Your internet speed is the total amount of data your device can download or upload in a second. The network’s bandwidth represents a ceiling for this speed, as it’s the maximum amount of data your device is allowed to download or upload per second. The throughput indicates actual speeds for all participants, which is what ultimately determines how fast your internet performs.

Once the bandwidth is subjected to real-world snags like traffic overload and high latency, it gives us the network’s throughput. Therefore, the wider the network’s initial bandwidth, the better its throughput and your internet speed.

Plus, a higher bandwidth makes sure no matter the number of people hopping onto your Wi-Fi network, your internet speed will remain consistent. Otherwise, if someone else ends up hogging your network’s bandwidth, your internet speed can dip dramatically.

At the same time, it’s key to remember bandwidth is a fixed resource on paper and not directly proportional to the internet speed. An internet service provider, for example, can offer higher bandwidth, and you can still end up with slow internet due to several other factors that can interfere with the connection in reality.

The throughput, in comparison, is a more direct representation of your internet speed, as it reflects the network’s real-time performance. However, it’s not a measure of just a single device. It’s the average of all the devices on a network, and there’s no guarantee your internet speed will be exactly equal to the throughput either.

Your internet speed itself is dependent on your circumstances. Your laptop, for example, might be outdated, and have an old Wi-Fi chip, which means it will limit your speed irrespective of how high the bandwidth or throughput is. Alternatively, your friend can get faster speeds because they’re connected to the internet via an Ethernet cable, and you could experience hiccups since you’re on Wi-Fi sitting far from the router.

So while bandwidth and throughput can paint a picture of your potential internet speed, they’re not the bottom line.

How does latency affect throughput?

Every action you take on the internet sends a request to a server. When you download an image, for example, you ping the server where the file is located and ask it for the relevant bits of data. The server then sends a request with the relevant information. The time it takes for both these requests to travel is called your network’s latency and it heavily influences its throughout.

Latency is inversely proportional to your network’s throughput. Any delay in your request’s roundtrip slows down your internet speed and makes the rest of your internet activities wait. A higher latency, therefore, means a lower throughput, and vice versa.

How to improve your network's throughput

If your internet is acting up often despite having a reasonably high bandwidth, there’s a chance the network is getting bogged down. Though it’s not possible to trace exactly what’s pulling it back, there are many aspects you can control and improve to hopefully boost your network’s throughput.

Free up congestion

One of the most common culprits behind low throughput is network congestion. This happens when there are too many users connected to the same channel and simultaneously eating up the bandwidth. If you have several devices at home connected to your internet, like your television, tablet, computers, etc., try disconnecting some, and see if it helps.

Upgrade your network hardware

Another factor that could potentially be hampering the throughput is low-quality networking equipment. You can take advantage of your network’s full bandwidth only when your equipment, like your router and cables, support the latest technology. The best path forward here is to check with your internet service provider and make sure you’ve deployed the correct equipment.

Use networking monitoring tools

You can equip network monitoring tools to understand whether there’s an app or software that’s covertly hogging the throughput on your computer. On a Mac, you can check your network activities from the “Network” tab in the Activity Monitor app. On a Windows PC, launch the Task Manager program and click “App History” to see how much data each of your installed apps have consumed. If you spot an app that’s using a suspiciously high amount of data, you can try updating or uninstalling it.

What throughput and bandwidth mean for you

Learning about network bandwidth and throughput is crucial to pick the right internet plan for you. It also helps you ensure your internet service provider is delivering on its claims and decide for yourself whether its network performance is adequate for your use.

There are also numerous factors you can look into to figure out how much internet speed you need and whether a high-end multi-gig speed internet makes sense for you.