Staying connected in Thailand.

This is a comfortable decision because both answers are cheap. An airport tourist SIM is roughly 9 to 18 dollars for a big or unlimited allowance over 8 to 30 days, with your passport, from counters that are open late and used to tourists. A Nomad eSIM at a few dollars per gigabyte lands in similar territory for a normal week's usage and activates before you fly.

So the tiebreaker is practical. The local SIM wins if you want a Thai number for Grab, hotel calls and app verifications, if you are staying a month, or if you are a heavy user on an unlimited plan. The eSIM wins if you land at 1am at Suvarnabhumi and would rather walk past the queue with data already working, if you are hopping between Thailand and neighbours on one regional plan, or if you want your US number to stay live on the physical SIM. Both beat roaming by a wide margin.

In Bangkok, Chiang Mai, Phuket and the main resort areas any network is fine and speeds are genuinely good. Outside them, AIS has the broadest footprint, including the northern hills around Pai and Mae Hong Son, the Isaan countryside and the smaller islands, with TrueMove H close behind and strongest in the cities and big resorts. If your trip is a Bangkok and Samui week, the difference will not show up; if it is a motorbike loop in the north, ask for AIS.

The thin spots worth knowing: the far northern hills and border areas, the interior of the big national parks such as Khao Yai and Khao Sok, some dive boats and the crossings out to the more remote islands, and stretches of the Mae Hong Son loop. The overnight trains and the ferries to the main islands hold a signal for most of the route.

Roaming is the expensive default here rather than a competitive option: AT&T and Verizon day passes are about 10 to 12 dollars a day, so a week is 70 to 84 dollars against about 12 dollars for a local SIM covering the same week. AT&T caps its Day Pass at 10 daily fees per line per bill period, about 120 dollars, while Verizon's TravelPass has no equivalent cap and keeps billing daily, which is worth knowing for the long winter trips Thailand attracts. T-Mobile's current tiers include roughly 5GB on Experience More, Magenta MAX and Go5G Plus, 15GB on Experience Beyond and Go5G Next and 30GB on Better Value, slowing to 256kbps after that, so a T-Mobile customer on a mid or upper tier may need nothing at all for a short trip.

The genuine bill-shock risk is roaming with no plan at about 2 dollars a megabyte, and Thailand is a place it happens, because a long-haul arrival at 1am with a dying phone is exactly when people switch data roaming on without thinking. Turn off data roaming before you land and leave it off until an eSIM, a local SIM or a pass is active. This guide is written for US travelers departing the US. For more, see cash or card in Thailand, taxis and apps in Thailand, and the Thailand money guide.

Common questions

Quick answers.

More on Thailand

The little money things nobody warns you about.

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