Why is my mobile data so slow?

We all have some bad days with our internet services from time to time, and mobile internet is no different. In mobile communications, the mobile internet is mostly referred to as mobile data or cellular data which can sometimes be slow.

Your mobile data may be slow due to poor coverage, throttling, outdated phone, or poor mobile operator selection. For slow mobile data, check if: your operator has decent 4G LTE coverage, the operator is not capping your speed, your device is up to date, and you are with a reliable operator.

In order to get good enough speeds on your mobile phone, all you need is to think about having a relatively newer phone model and not a very old SIM card. Since I raised the terminology point, let me elaborate on that before diving into further details. LTE is the technology within a mobile network and the mobile phone that connects you to the 4G network. Similarly, NR (New Radio) is the technology within the mobile network and your phone that connects you to the 5G network. Mobile operators keep adding new functionalities and enhancements to their networks all the time. For you to benefit from those enhancements, you need some updates on your device also. That is where the different device categories come in, for example, LTE category 16, 17, etc. These enhancements include hardware capabilities that impact the maximum achievable download/upload speeds. But as mentioned earlier, as long as you have a relatively newer phone model, you shouldn’t have to worry about that so much.

What is the normal speed of mobile data?

Before looking at the reasons why your mobile data might be slow, let’s find out what real-life data speeds you can actually expect. The straightforward rule is to expect higher data rates from newer generations and enhancements as long as you have a compatible device that supports it. The table below provides a summary of what data speeds you can normally expect from your mobile data. Looking at the extreme cases – if you are on a 5G network and you have a 5G device, then you can expect average speeds of around 150 Mbps to 200 Mbps in the UK at the time of writing (Aug 2021). Similarly, if you are on a 2G GSM network and are served by one of the initial data enhancements, EDGE, then you shouldn’t expect more than 200 kbps.

Network Generation/TechnologyRelevant symbols & abbreviationsAverage speed*
5G – NR5G, NR150-200 Mbps
4G – LTE Advanced4G +, LTE+, LTE-A50-80 Mbps
4G – LTE4G, LTE15-20 Mbps
3G – UMTS – HSPA+H+5-8 Mbps
3G – UMTS – HSPAH<5 Mbps
3G – UMTS3G384 kbps
2G – GSM – EDGEE130-200 kbps

Network technologies, symbols and expected average speeds—[* Reading, UK, 2021, and can vary a lot depending on your operator, location, etc.]

Is it really your mobile network that is slowing you down?

The first thing you want to check is if it really is the mobile network that is slowing you down. Sometimes, when you are connected to a WiFi network with poor signal quality, your phone may continuously switch between the WiFi network and the cellular network. As a result, you may get inconsistent overall connectivity. If the WiFi is slowing you down, switch off the WiFi on your phone or disconnect the particular WiFi connection that is slowing you down. That way, the phone can “freely” benefit from the mobile data.

Connected to both WiFi and mobile networks

How do I know if my mobile internet is slow?

Once we have ruled out the possibilities of multiple connection types slowing us down, we can focus solely on mobile data. A mobile data connection is dependent on three things; your device, your network and your subscription (tariff). Problems or limitations with any of these can negatively impact your mobile data speeds.


The mobile device is something you can easily check and control, so it is important to get the device checks out of the way as soon as you can. If you run a Google search, you can find tons of blog posts that will give you tips and tricks on addressing device-related data speed issues. Feel free to go through the checklist, although as a telecom person, the only ones that I think are worth considering are the following:

  1. Restarting your phone – This one can help soemtimes.
  2. Try multiple apps and browsers including speed checks through apps like Ookla before drawing any conclusions on the data speed.
  3. Make sure your phone is not locked to a lower network technology (e.g. 3G, 2G) than what it is capable of. So, if you have a 5G phone, make sure your preferred network is set to 5G. Similarly, if it is a 4G phone, make sure your preferred network type is set to 4G.
  4. Finally, if you have another device handy e.g. someone else’s phone, you can insert your SIM into that phone to find out if the results are the same. For this one to work, you need an unlocked phone unless the other phone is locked to the same mobile operator as the one you are using.


If your device is not slowing you down, you need to check if it is the mobile network that is causing the data speed issue. The most important thing to check in that regard is to see which network technology you are most connected to. So, if you have a 4G phone but you mostly find yourself on the 3G network, e.g. seeing symbols like 3G, H, H+, symbols, you may have a 4G network coverage issue. Similarly, if you bought yourself a new shiny 5G capable phone, but you only get 4G network coverage in your desired locations, then the results won’t be as appealing. Look at the table above to determine if the average speeds you are getting on 3G, 4G and 5G networks are similar to what we have captured. At the time of writing (Aug 2021), in Reading UK, we have already recorded outdoor 5G speeds of up to 450-500 Mbps+, which means that the table above is not optimistic at all.


Mobile operators have MANY tariffs, and even the tariffs that allow you to access the same 4G or 5G network may not allow you to use the same network features. For example, there are tariffs in the UK that allow you to use the 4G LTE network, but they may limit your maximum download/upload speeds. The easiest way to spot that is if you suddenly find a tariff price that looks too good to be true. If you encounter a tariff like that, always check the details around speed caps (throttling) and network types (4G, 5G). Throttling is when mobile operators put a cap on your maximum download/upload speeds. For example, some tariffs may use throttling to control customers’ data usage after exceeding their data allowance.

What if my mobile data is slow all of a sudden?

If your mobile data speeds were as per your expectations and the change happened all of a sudden, then it is likely that whatever the issue is, it may not be a long term issue. You can do the device and network checks as explained above and if that doesn’t help, give it some time. Often, mobile networks can run into capacity issues due to maintenance or any sudden changes in the network demand. If for whatever reason, many new people start using the same base station (cell) that you are connected to, it can negatively impact your data speed. For example, if you live close to a train station or stadium or a big shopping mall where big crowds gather, there may be times when your mobile data speeds go down in busy hours. But if you have a good mobile operator, they will manage the necessary capacity demands by investing in additional network resources to address the needs.

What if I am on 4G and my 4G data is slow?

4G LTE networks have different versions, including the regular LTE, LTE-Advanced and LTE-Advanced Pro. It is imperative to select your mobile network operator carefully. You want to be with a mobile operator with the right coverage levels in your locations of interest. For example, if you spend most of your time in two or three locations, e.g. home, office, gym etc., you want to be with a mobile operator who covers those areas well. And covering doesn’t mean just having 2G/3G/4G coverage to tick the coverage box, but having advanced 4G coverage. If your mobile operator has a good 4G coverage, but the speeds on your phone are never higher than 15-20 Mbps, then either they don’t have LTE-Advanced in their network -OR- your device does not support the latest network enhancements. In both cases, check with your mobile operator because they can tell you exactly which network resources (cells) are serving you and what speeds you should be getting. If you want to do the checks yourself, search for “cellular tower” in the app stores to find an app that can tell you which cell is serving you. You can also check your device specs on the GSM arena’s website to find out which network technologies your device supports. You can check out our dedicated post to learn about the average 4G LTE speeds and latency.


There are many reasons why your mobile data might be slow. If your data speeds are slow, the key things to investigate are your device, network support, and tariff type. You need at least the basic 4G LTE network connectivity for average speeds of around 15-20 Mbps. LTE-Advanced can offer higher speeds, and 5G networks can improve the speeds even further. Getting a higher data speed depends on which network you are allowed to use as part of your mobile tariff (subscription), what the network coverage is in your geographical location and if your device supports the network technology that will give you the desired speeds.

Here are some helpful downloads

Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support, especially when preparing for a new job, studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:

Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.

Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.

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