Travel eSIM or a local SIM card? The honest comparison
The airport SIM kiosk is the default answer for a lot of travellers, and for some trips it is still the right one. But the comparison is rarely made honestly — it is usually eSIM marketing against a strawman, or a kiosk price quoted without the queue. Here is the actual trade-off, including where the local SIM wins.
The four differences that matter
1. When you get connected
An eSIM installed before departure is working within a minute or two of leaving airplane mode. A local SIM means finding the counter, queueing, handing over your passport in most countries, waiting for registration, and swapping a tray in an arrivals hall. On a good day that is twenty minutes. On a bad day the counter is closed because you landed at 2am.
This matters most in the exact window where you need data most: working out where the taxi rank is, or messaging whoever is meeting you.
2. What happens to your own number
This is the difference people notice after the trip, not during it. Putting a local SIM in the tray means taking your own out — so your normal number stops receiving calls and, critically, SMS verification codes from your bank. Plenty of people have discovered mid-trip that their banking app wants a code sent to a SIM sitting in a hotel-room drawer.
An eSIM adds a second line instead of replacing the first. Your usual number stays live for calls and texts; the eSIM carries data. Nothing is swapped, and nothing small gets lost.
3. Price
Local SIMs are often genuinely cheap, especially for large data bundles in Asia and the Middle East. Airport prices, though, are rarely the prices advertised in town — kiosks price for a captive audience, and tourist bundles frequently cost several times what a local pays at a supermarket.
In Thailand, our plans start at £2.49 for 1 GB, with 5 GB at £6.49. For a short trip that is usually at or below the airport price once you include the time. For a month-long stay with heavy data use, a local prepaid SIM bought in a city shop will often still beat it — and that is a fair result to state rather than hide.
4. Coverage
A local SIM gives you one network. A travel eSIM roams, which means it can use more than one — in Thailand that is AIS, DTAC, TrueMove H. Where a single operator has a weak patch, the roaming profile can fall back to another. This is the one technical advantage of a travel eSIM that has nothing to do with convenience.
When the local SIM is genuinely the better buy
- Long stays. Beyond about three weeks in one country, a local prepaid plan bought in town usually wins on price per gigabyte.
- You need a local phone number. For a delivery app, a local bank, or anything that texts a code to a domestic number, a data-only eSIM will not do it.
- Very heavy data use. Tethering a laptop all day for weeks is where local unlimited-style plans still have the edge.
- Your phone cannot take an eSIM. Settled in thirty seconds by dialling *#06# and looking for an EID — see device compatibility.
When the eSIM is clearly better
- Trips under about two weeks, where setup time is a real fraction of the trip.
- Multi-country trips. One regional profile from £1.49 replaces a SIM purchase at every border. Regional or local covers where the line falls.
- You need your own number to keep working — bank codes, work calls, family.
- Late arrivals and small airports, where the kiosk may be shut.
- Newer iPhones bought in the United States, which have no SIM tray at all. A local physical SIM is not an option on those.
The short version
For most trips of a week or two, an eSIM bought before you fly wins on time, on keeping your own number, and usually on total cost once the airport markup is counted. For a long stay in one country with heavy use, buy local — in a city shop, not at arrivals.
If you are comparing against your home carrier's roaming instead, that is a different sum: eSIM vs roaming vs a local SIM works it through.
