eSIM, roaming or a local SIM: what each one really costs in 2026
An honest comparison of the three ways to get online abroad — including when roaming is the right answer and when a local SIM still wins.
onesim team
There are three ways to have working data in another country, and the internet is full of people insisting that one of them is always right. It is not.
Here is what each actually costs, and the situations where each one wins.
The short version
| Roaming on your own plan | A local SIM | A travel eSIM | |
|---|---|---|---|
Set-up | None | Shop, passport, sometimes a queue | Installed before you fly |
Typical cost | £2–3 or $5–12 a day | Cheapest per GB | Between the two |
Your own number | Keeps working | Usually lost while it is in | Keeps working on the other line |
Runs out how | Charged, or throttled | Stops, top up locally | Stops, buy another package |
Best for | Short trips inside your own roaming zone | Long stays in one country | Most trips of 3–21 days |
Roaming: fine inside your zone, expensive outside it
If you have an EU or EEA plan and you are travelling inside the EU, stop reading. Roam-like-at-home means your domestic allowance works across the union at no extra charge, and the rules run to 2032. Nothing beats free.
Outside that, roaming is sold by the day.
- UK networks mostly reintroduced European roaming charges after Brexit, at roughly £2 to £3 a day — EE around £2.47, Vodafone and Three around £2, with O2 still the exception on standard consumer plans as of mid-2026. Outside Europe it is much more.
- US networks sell day passes at roughly $5 to $12 a day per line depending on carrier and plan. T-Mobile's is the cheapest of the three big ones; AT&T and Verizon sit at the top of that range.
- Everywhere else varies enormously, and pay-as-you-go roaming without a pass is where the horror stories come from.
The arithmetic is simple: a day pass is good value for two or three days and bad value for two or three weeks. At £2.50 a day, a fortnight in Spain from a UK plan is £35 before you have used a single megabyte.
Roaming wins when: you are inside your own free zone; the trip is two or three days; you need your own number for calls and texts, not just data; or your plan genuinely includes the destination.
A local SIM: still the cheapest per gigabyte
Buy a SIM in the country you are visiting and you get local prices, which in Thailand, Türkiye, Indonesia or most of the Balkans are dramatically lower than anything a foreign company can sell you.
The costs are not financial. You need to find an official shop rather than an airport kiosk with a markup. Many countries require passport registration, which takes time. Your own number is out of the phone unless it is dual-SIM. And in some places there are rules that catch visitors out — Türkiye, for example, requires foreign handsets used with a Turkish SIM to be registered against your passport after a set period, or the phone is blocked on Turkish networks.
A local SIM wins when: you are staying a month or more; you are in one country rather than several; you need a local number for deliveries, banking or a landlord; or you need very large amounts of data.
A travel eSIM: the middle, for most trips
A travel eSIM is a data package you install before you leave, over Wi-Fi, from home. There is no shop, no queue and no plastic. Your physical SIM stays in the phone, so your own number still receives calls and texts while the data runs over the travel line.
The honest limitations, so nobody is surprised:
- Your phone must support eSIM and be carrier-unlocked. Most phones from the last five years do; some regional variants and carrier-locked handsets do not.
- Most travel eSIMs are data only. No local number, no SMS. For two-factor codes, keep your own number reachable.
- A package is tied to a region or a country list. Crossing outside the list means no data until you buy something that covers where you are.
A travel eSIM wins when: the trip is roughly three days to three weeks; you are crossing several countries in one region; you want the price fixed before you go; or you simply do not want to solve a connectivity problem in an arrivals hall at 1am.
What this looks like in numbers
A two-week trip through Italy, Croatia and Greece, from a UK plan:
- Roaming: 14 days at about £2.50 = £35, and your full domestic allowance.
- Local SIMs: three SIMs, three shops, three registrations. Cheapest per gigabyte, worst per hour of your life.
- One regional eSIM: a single package covering all three countries, bought before you fly, at a price you saw before you paid.
For the same trip from a German plan, roaming wins outright, because all three countries are inside the EU zone.
That is genuinely the answer: check your own zone first. If the trip is inside it, do nothing. If it is not, compare a day pass against a package for the length of the trip, and take the smaller number.
What to check before you buy anything
Before you pay for any of the three
- Does your existing plan already cover the destination, and at what daily rate?
- Is your phone eSIM-capable and carrier-unlocked?
- Does the package cover every country on the route, not just the first one?
- What happens when the data runs out — does it stop, throttle, or charge?
- Do you need a local number, or only data?
