eSIM vs roaming vs local SIM

Option 1: your carrier's roaming

The simplest option, because there is nothing to do. Your phone connects on landing using your normal number, and you are billed either nothing or a daily rate depending on your plan and destination.

Inside the European Union, plus Iceland, Liechtenstein and Norway, EU residents get roam like at home under EU rules, so their domestic allowance travels with them subject to a fair use policy - see the official Your Europe guidance. Outside an inclusive zone, roaming turns into a daily pass or a per-megabyte rate, and the per-megabyte rate is where holiday phone bills become news stories.

Best when: your destination is genuinely included in your plan, or your trip is short enough that two or three daily passes cost less than an eSIM plus the effort.

Option 2: a travel eSIM

You buy online before you leave, install on home wi-fi, and switch it on when you land. Prices are set per destination and per data bundle rather than per day, and almost all travel eSIMs are data-only, so your home number stays on your other line for calls and texts.

Best when: your destination is outside your inclusive roaming zone, your trip is longer than a couple of days, and you want a fixed cost known in advance.

Option 3: a local prepaid SIM

Bought on arrival from a kiosk or a phone shop. You get a local number and domestic pricing, which is genuinely the cheapest data available almost everywhere.

The costs are elsewhere. Airport kiosks charge a captive-audience premium over the same SIM bought in town. Several countries require identity registration before activation. Your home SIM has to come out unless your phone has two slots. And you spend part of your first day in a queue rather than at your hotel.

Best when: you are staying for a month or more, you want a local number for taxis and deliveries, or you need very large amounts of data.

Worked example: ten days in Thailand

A traveller expecting to use around 10GB. Using verified prices from our Thailand comparison, Saily sells 10GB over 30 days at $10.99, and Airalo sells 20GB over 30 days at $18, which works out at $0.90 per GB. Either covers the trip comfortably for roughly the price of two airport coffees.

Against that, a typical daily roaming pass outside an inclusive zone costs several pounds a day, so ten days of roaming is usually a multiple of the eSIM cost for the same connectivity. A local Thai tourist SIM would be cheaper still per gigabyte, but requires a kiosk visit on arrival and, on a single-SIM phone, means losing access to your home number for the trip.

Worked example: a weekend in France

Two nights, light usage. For an EU resident this is easy: roam like at home means the domestic allowance applies and buying anything is a waste of money. For a traveller from outside the roaming zone the calculation changes - Ubigi sells 3GB over 30 days for France at $4, which is likely to cost less than a single day of carrier roaming.

This is the general shape of the decision. Short trips inside an inclusive zone favour roaming. Everything else favours an eSIM, and only long stays favour a local SIM.

Side by side

The one-minute rule

1. Check whether your destination is included in your existing plan at no extra cost. If it is, stop - use roaming.
2. If not, and the trip is under a month, buy a travel eSIM before you fly and keep data roaming switched off on your home line.
3. If the trip is a month or more, or you need a local number, plan on a local SIM but still carry a small eSIM for the first day so you land connected.

Step 3 is worth taking seriously. Buying a cheap short eSIM to bridge your arrival costs a few dollars and removes the worst hour of any trip - see eSIMs for long trips.

Compare real prices

Every price in this guide came from our destination tables, where each figure is dated and linked to the provider page it was read from. Work out how much data you need first with how much eSIM data do you need.

Compare prices for your destination

Common questions