Thailand eSIM for Bangkok, Chiang Mai, the islands, and the borders

Thailand is a Grab from the airport, a QR code at the street stall, and a ferry to an island where the resort's Wi-Fi stops at the pool, and Suvarnabhumi's arrivals hall is the place to have a phone that already works. The best eSIM for Thailand is the one added at home, on Wi-Fi, so the Airport Rail Link is tapped through and the Chiang Mai sleeper booked before the SIM sellers reach you.

Below: how a Thailand plan works, how to set it up before you fly, what to expect in Bangkok, the north, and the islands, and why a Southeast Asia loop wants the Asia plan.

Asian trips tend to be multi-stop, and most travel eSIMs want a fresh profile at every airport. KnowRoaming doesn't. You add the KnowRoaming eSIM, called KR.One, to your phone once, then add a plan per trip: one country for a single-city break, the Asia plan when the route runs through several, and next year's trip on the same eSIM. Nothing to scan again, nothing to delete when you get home.

The plan's days start when you turn it on and connect in Thailand, not at checkout. Buy it weeks ahead, add it at home, and a delayed flight costs you nothing. The full rule is in what plan validity means and when it starts.

Choose a fixed plan for a set amount of data at the lowest overall price, or an unlimited plan when you'd rather not count. Unlimited plans give you 5 GB a day at full speed, then a slower speed until the allowance resets the next day. If a fixed plan runs low, top up in the app and the extra data lands on the same eSIM.

See it in two minutes: Meet KR.One, iPhone setup with KR.One, or Samsung setup with KR.One.

Do this at home on Wi-Fi. It takes about a minute.

Before you leave

1. Get the KnowRoaming app (available on iOS and Android) and choose your Thailand plan.
2. Tap Add. First time on this phone? The app adds KR.One and your Thailand plan together. Already have KR.One? Only the plan is added, with nothing to scan.
3. Leave data roaming off on the KnowRoaming line until you land, and turn it off on your home line too so it doesn't run up charges in the background. Steps are in turning off roaming on your home line.

When you land

1. Turn the plan on in the app, then turn data roaming on for the KnowRoaming line. That setting lives in your phone, so the app can't flip it for you.
2. Give the phone a minute to find the network. If nothing happens, turn airplane mode on for 30 seconds and off again.

Prefer a QR code? The checkout page and your confirmation email both carry one; scan it from your phone's settings. Every tap, by device, is in adding your eSIM on iPhone, adding your eSIM on Android, and adding your eSIM on Samsung, or watch the iPhone QR walkthrough or the Samsung QR walkthrough. Still no signal after landing? Work through the no-signal checklist.

Suvarnabhumi's Airport Rail Link reaches the city in about half an hour, and Grab and Bolt run from both Bangkok airports with the number you already have; the BTS Skytrain and the MRT take a contactless card on the gates. Most passports enter visa-free and complete the digital arrival card online before the flight; keep it saved offline. The baht is the currency, cards work in the malls, hotels, and chain restaurants, and cash covers the street food, the markets, and the islands.

PromptPay, the QR system that Thailand pays with, needs a Thai bank account, so visitors pay by card and carry cash; the plan keeps the bank app on data for the card approvals. The Grand Palace, Wat Pho, the Chatuchak weekend market, and a canal boat are the first days.

Chiang Mai is an hour's flight or the overnight sleeper, booked in the State Railway's app, with the old city's temples, the Sunday walking street, and the elephant sanctuaries that confirm by message; Pai's mountain road, Chiang Rai's white temple, and the Golden Triangle are the further north. AIS's 5G covers the cities and 4G the highways; the mountain roads and the hill-tribe villages thin out.

Ayutthaya's ruins and Kanchanaburi's bridge are the day trips from Bangkok by train, both with 4G; Khao Sok's lake in the south and Khao Yai's forest north of the capital are the jungle nights, offline at the rafthouses.

Phuket's beaches and the boats to Phi Phi, Krabi's Railay by longtail, and Samui, Phangan, and Tao by ferry from Surat Thani are the islands, with the ferries and the speedboats booked online and canceled by the monsoon; the Full Moon party on Phangan fills the ferries each month. AIS's 5G covers Phuket and Samui's towns, 4G the resort beaches, and the boats, the far bays, and Tao's dive sites drop out.

Thailand is on the Asia plan, 28 countries on one plan that also covers Laos, Cambodia, Malaysia, Vietnam, and Singapore, switching networks by itself at the Friendship Bridge, the Poipet crossing, and the Malaysian border; a Southeast Asia loop fits it without any change in the app. Thailand is also on the Global plan. A Thailand-only plan stops at the border. Read do I need a new plan for every country? for the detail.

Chiang Mai, Bangkok, and the islands are long-stay places for remote workers, with a long-stay visa aimed at them, fast 5G, and coworking everywhere; for a stay of weeks, an unlimited plan, with 5 GB a day at full speed, covers calls and the hotspot. Songkran in April soaks the whole country for three days, Loy Krathong in November lights the rivers, and the monsoon swaps coasts, with the Andaman wet from May to October and the Gulf from October to December.

Your plan connects to AIS, with 5G in Bangkok, Chiang Mai, Phuket, Pattaya, Samui, and the other cities and resort towns and 4G LTE across the highways and the islands. Your phone picks the network automatically once the plan is on; there is nothing to choose by hand.

On the northern mountain roads, the hill-tribe treks, the boats between islands, and the dive sites, expect gaps on any network. Save what you need in town.

Most phones sold since 2019 support eSIM, including iPhone XS and later and most Android flagships from the same window. Check yours before you add a plan; it takes a few seconds. On iPhone, go to Settings, General, About and look for an EID or Available SIM. On Android, go to Settings, Network & Internet, SIMs and look for an option to add an eSIM. On Samsung, dial *#06# and look for an EID.

Your phone also needs to be carrier-unlocked. If you're not sure, carrier-locked vs unlocked: how to tell shows you where to look.

Adding a Thailand plan doesn't touch your regular SIM. Calls and texts on your usual number keep working exactly as before. The new plan handles data while you're there, and most phones run both at once without you doing anything else. Bank codes and two-factor texts still arrive on your home number, as long as that line stays switched on.

For Asia the alternatives are a home-carrier roaming pass that resets at every border, an airport SIM counter at each arrival, or hotel Wi-Fi that stops at the lobby. A Thailand plan added at home beats all three: one price agreed before you fly, live the second you land, and one plan across every stop on the route.

Real travelers rate KnowRoaming 4.5 out of 5 on Reviews.io. More than a decade in travel connectivity, more than 200 destinations, and support that doesn't clock off: WhatsApp and live chat, any time, any day.

One plan. No roaming surprises. Live the moment you land.

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