In short: The actual speed of an eSIM depends on the local operator's network, not the eSIM itself, so it almost never matches the "full-speed 4G/5G" they advertise. With 5-10 Mbps, you can browse, use maps, and watch HD video without a problem: for traveling, you need much less speed than you think, even if you don't reach the theoretical maximum published.
Why isn't the actual speed what's advertised?
You buy a travel eSIM, see the promise of "full-speed 4G/5G" on the plan's details, and then load Instagram at the airport and it doesn't work as you expected. It's not a scam: it's how mobile networks work anywhere in the world, with or without an eSIM. The advertised speed is a theoretical maximum for the technology, measured under laboratory conditions, not a promise of what you'll see on your screen.
Simply put: an eSIM gives you the same speed a local would have with that operator, in that location, at that exact time. There's no special or worse "eSIM speed"; you use the country's infrastructure as it is, with its antennas, saturation, and coverage. That's why in downtown Tokyo you'll go super fast, and in a mountain village in the Alps, you won't, even if both eSIMs are identical.
Think of it like a car's advertised fuel consumption: the manufacturer gives a figure measured under perfect conditions, and then your actual consumption depends on how and where you drive. The same goes for connectivity. The advertised speed is the showroom; what you see on your phone is the result of your specific situation: operator, city, time of day, and how many phones are competing for the same antenna at that moment. Understanding this saves you frustration during your trip and helps you choose a plan wisely, without falling for "unlimited speed" promises that no network on the planet can guarantee everywhere at once.
What 4G and 5G really mean
In practice, good 4G/LTE gives you between 10 and 50 Mbps download, more than enough for almost everything a traveler does: maps, HD streaming, video calls, and social media without interruptions. 5G can reach hundreds of Mbps where it's truly deployed (not just the icon on the screen), but for checking a map or sending photos via WhatsApp, you won't notice a difference compared to decent 4G. The difference of 5G is noticeable for heavy downloads or sharing a hotspot with several devices at once, not in everyday mobile use.
| Technology | Typical real speed | Sufficient for |
|---|---|---|
| 3G | 1-5 Mbps | Messaging, maps, light websites |
| 4G / LTE | 10-50 Mbps | HD streaming, video calls, all normal use |
| 5G | 100-500+ Mbps | Large downloads, intensive hotspot, multiple devices |
One nuance that many people miss: the "5G" icon in the status bar doesn't always mean real 5G. Some operators show "5Ge" or similar on a network that is actually still improved 4G. If you want to delve deeper into the generation leap and in which destinations 5G is already widely deployed, you can find more details on how to install an eSIM step by step before landing, so that configuration doesn't take away network minutes upon arrival.
Factors that slow down your eSIM
Before blaming the eSIM, check what's actually limiting the connection. It's almost always a combination of these factors, and none have to do with it being an eSIM instead of a physical card:
- Location coverage: inside a stone building, in a valley, or going underground, the signal drops even if the plan is max speed. Old hotels with thick walls are among the worst places to measure speed.
- Network saturation: at a festival, a crowded airport, or the historical center at midday, thousands of phones compete for the same antenna. Speed drops even if the coverage is full.
- Your phone: an older device may not pick up the specific 4G/5G bands used by the local operator, even if it works perfectly in Spain with those same bands.
- Data policies: some plans reduce speed after consuming a certain daily allowance; it's advisable to read the fine print before assuming it's "unlimited" without caveats.
Key fact: if your plan says "unlimited data," there's almost always a period of maximum speed, and then it's reduced. This isn't a trap exclusive to travel eSIMs; traditional physical tariffs also do it.
To avoid surprises with this, it's also important to understand the difference between using an eSIM and activating roaming with your home operator: they are distinct mechanisms and affect speed and cost very differently. And if you've never used data outside your country, you'll want to know exactly what data roaming is before comparing plans.
How to measure your real speed
Measuring is easy and removes doubts in 30 seconds. Use a reliable speed test (Speedtest or similar) and follow these rules for a fair and comparable test:
- Do it outdoors, with good signal, not inside the hotel or in the basement of a museum.
- Check that your phone shows 4G or 5G in the status bar, not 3G or "E" (that already tells you it will be slow before testing).
- Repeat at different times: the network doesn't perform the same at three in the afternoon downtown as it does late at night in the suburbs.
- Note the latency (ping) in addition to the download speed: for video calls, it's as important as Mbps, or more so.
If the test results are good but a specific app is slow, the problem is usually with that app or its server, not your eSIM. This is an easy nuance to forget: Netflix or Zoom might have servers further away or more saturated in one country than another, and no SIM card can fix that.
Speed you need per task
The good news: for traveling, you need much less speed than you think. An average traveler is perfectly fine with normal 4G, without even getting close to the published maximum:
- WhatsApp and maps: 1-3 Mbps is more than enough.
- Social media and browsing: 5-10 Mbps is fluid, with no waiting when loading photos or short videos.
- HD streaming and video calls: 5-15 Mbps is enough to avoid seeing the loading symbol in the middle of a series.
- Hotspot for laptop: the more, the better, but 20 Mbps already provides an office experience for answering emails or making a work video call.
In other words, even if you don't reach the advertised maximum, you almost certainly have more than enough for what you do during your trip. If you're going to work on the go or need to connect your laptop, check out how to safely use a VPN while traveling without privacy costing you extra speed.
A note on latency that almost no one measures: Mbps indicates how much data passes, but ping measures how long each packet takes to go and return. For browsing or watching video, it hardly matters, but in video calls or games, high ping is more noticeable than a few less Mbps. If your call cuts out with good download speed, the culprit is almost always the network's latency at that moment, not the eSIM or the plan you purchased.
What almost no one tells you
There are a series of small details that explain most of the "my eSIM is slow" inquiries that reach support, and almost none have to do with the quality of the plan:
- The "data roaming" switch must be activated on the eSIM line, even if you're not going to roam with your home operator. This is one of the most confusing things: in your phone's settings, within the eSIM line, there's a data roaming option that may be deactivated by default, and if it is, the eSIM simply won't browse even if it shows full coverage.
- Battery saver mode limits background data speed. If you activate power saving as soon as you land to extend your flight's battery, you might notice the connection is slower than usual: the operating system itself is slowing down processes and downloads to consume less.
- With dual SIM, check which line has mobile data assigned. If the phone is still using your physical home SIM for data by mistake, you might see coverage but incur expensive roaming charges, or simply not browse if that line doesn't have active data. This is one of the most common oversights upon arrival at your destination.
- A VPN always reduces speed somewhat, due to encryption and the distance to the chosen VPN server. This is not an eSIM fault: if you need a VPN for work, choose a server close to the country you're in, not one on another continent.
- Manual network selection can save your afternoon. If your eSIM allows it and you notice that the automatic operator is saturated (typical at a massive event or a bustling airport terminal), manually switching to another operator with coverage in the area sometimes instantly improves speed.
And one thing that needs to be said honestly, even if it's not a selling point: if you travel within the European Union with a home operator that includes roaming at no extra cost, your usual tariff already covers you with the same speed as at home, and buying an additional eSIM won't make you go faster. In that case, the eSIM makes sense for other reasons (a second line, avoiding touching your main SIM, or traveling outside the EU where roaming costs do skyrocket), but not for speed. Where the eSIM truly makes a difference is outside the EU: on a long trip to the United States, for example, with no roaming involved and no surprises on the bill upon return.
How to get more speed
If you notice it's slow, try these adjustments before giving up and thinking the plan is bad:
- Restart the connection: activate and deactivate airplane mode so the eSIM reconnects to the best available antenna at that moment.
- Force 4G/5G in network settings if the phone got stuck on 3G for some reason.
- Move a few feet or go outside: sometimes a thick wall or a metal roof changes everything.
- Manually select the network if your eSIM allows it, to escape a saturated operator at that specific point.
- Check system data saver settings: some phones limit background apps that you're not using on screen, which can appear as slowness when it's actually an app being intentionally slowed down.
And if you suspect the problem is configuration rather than network, this list of common problems when setting up an eSIM will help you diagnose it step by step. To squeeze every megabyte when the network is tight, don't forget the tricks to save data abroad, which are useful whether you have plenty of speed or are pushing your plan to the limit.
Frequently asked questions
Is an eSIM slower than a physical SIM?
No. eSIMs and physical SIMs use exactly the same local operator network, so the speed is identical under equal conditions. The difference is in activation convenience (you scan a QR code and you're done, without waiting at a store), not in connection performance.
Why is my eSIM slow if I have 5G?
Having the 5G icon doesn't guarantee maximum speed: there might be antenna saturation, poor actual coverage of that specific band where you are, or plan limits after a certain consumption. Try running a speed test outdoors and at different times to see what you actually get, not just what the icon promises.
How do I know my real speed?
With a speed test app like Speedtest, outdoors and with good signal. Pay attention to download speed (Mbps) and ping. Repeat the test at various times, because the network changes a lot depending on the time and the number of people connected around you at that moment.
Is the advertised speed a lie?
No, it's a theoretical maximum of the technology under ideal conditions, not a promise of what you will see. It works just like your home fiber optic: you contract a speed "up to X" and in practice you get something less depending on many factors that are not up to the provider.
How many Mbps do I need for travel?
Very few: with 5-10 Mbps, you can browse, use maps, watch HD video, and make video calls without a problem. So, even if you don't reach the advertised maximum, you'll almost always have enough speed for everything you do during your trip.
Why does my eSIM show coverage but nothing loads?
Most commonly, the "data roaming" switch for that line is deactivated in your phone's settings, or, on a dual SIM phone, data is still assigned to the other line. It could also be temporary saturation of the antenna you're connected to; try restarting the connection before assuming the plan is failing.
Does speed vary much between countries?
Yes, quite a lot. It depends on the network deployment of each local operator, not the eSIM. In very dense cities, the network can be overloaded at certain times, and in rural or mountainous areas, coverage can simply be 3G or non-existent, with or without an eSIM. Before a trip with remote sections, it's advisable to download offline maps just in case.
Conclusion
The actual speed of an eSIM depends on the country's network, the location's coverage, and the saturation at the moment, not a trick by the provider: that's why you'll rarely see the advertised maximum, and you don't need it to travel well-connected. Measure with a test, check roaming and dual SIM settings before blaming the plan, and always choose an honest provider about what they promise. At PuraSIM, we work with more than 200 destinations and offer 24/7 support via email and WhatsApp in all languages, so if something doesn't go as expected, you have someone to talk to. With a quality eSIM, you'll have more than enough speed to travel connected without surprises, whether for moving around Europe or for a long trip with an eSIM for the United States.
