One eSIM for Singapore, Malaysia, Thailand and Vietnam — priced per day

A four-country trip is the itinerary that makes sensible people buy four SIM cards: one at Changi, another in Kuala Lumpur, a third at Suvarnabhumi, a fourth in Ho Chi Minh City. Four passport registrations, four top-ups, four phone numbers you will never use again — and airport counter prices at every stop.

One plan on our shelf replaces all of it. It covers Singapore, Malaysia, Thailand and Vietnam, and it starts at HK$9 for a single day. That is the lowest entry price we sell.

What follows is not a sales page. It is the arithmetic of this specific plan, because two things about it decide what you actually pay, and neither is on the product page in plain language: the plan is sold in six fixed lengths, and its daily allowance resets at midnight Hong Kong time — which is not midnight in two of the four countries.

What the four-country plan actually is

Straight from the product page, country by country:

Country	Network	Why it matters
Singapore	Singtel	The incumbent, and the best indoor coverage on the island
Malaysia	Celcom and Digi	Two networks listed — you can switch between them by hand
Thailand	Truemove	Strong nationwide, and the network most resort areas are built around
Vietnam	Vinaphone	The second-largest network in the country, not a budget reseller

Malaysia listing two networks is the most useful line on that page. Most travel eSIMs give you one network per country and no say in it; here, when Celcom dies inside a mall, you go into settings and pick Digi. It is a two-minute fix that most people never discover they have.

The rest of the spec: 4G and 5G, data only, APN CMHK/CMLink, no identity verification required, delivered by email in 5–10 minutes, and it activates automatically the first time it connects to a network — as long as that happens within 30 days of purchase. The 30-day window matters: install it at home, fly three weeks later, and it still works.

The six lengths, and what they cost

Every price in HKD, for the whole plan. Four data tiers, six lengths, twenty-four combinations, all in stock.

Length	1 GB/day	2 GB/day	5 GB/day	Unlimited
1 day	HK$9	HK$12	HK$15	HK$17
3 days	HK$22	HK$29	HK$38	HK$45
5 days	HK$34	HK$46	HK$62	HK$73
7 days	HK$47	HK$63	HK$85	HK$101
10 days	HK$65	HK$89	HK$120	HK$143
15 days	HK$97	HK$132	HK$179	HK$214
Per day, 1 GB	HK$9.00	HK$7.33	HK$6.80	HK$6.71

The bottom row is where the real story sits. Those six numbers fall all the way down — 9.00, 7.33, 6.80, 6.71, 6.50, 6.47 — which is unusual: most providers stop discounting at seven days and charge a flat rate after that. Here the fifteen-day plan is 28% cheaper per day than the one-day plan. You just have to stay fifteen days to collect it.

The part nobody warns you about: the ladder has gaps

There is no two-day plan, no four-day plan, no eight-day plan. So the price you pay is not a function of how long you travel — it is a function of which step you land on. Here is every trip length from 1 to 15 days, with the cheapest sensible plan for each, in the 1 GB tier:

Trip length	Plan you buy	Price	Cost per day you are actually there
1 day	1 day	HK$9	HK$9.00
2 days	3 days	HK$22	HK$11.00
3 days	3 days	HK$22	HK$7.33
4 days	5 days	HK$34	HK$8.50
5 days	5 days	HK$34	HK$6.80
6 days	7 days	HK$47	HK$7.83
7 days	7 days	HK$47	HK$6.71
8 days	10 days	HK$65	HK$8.13
9 days	10 days	HK$65	HK$7.22
10 days	10 days	HK$65	HK$6.50
11 days	15 days	HK$97	HK$8.82
12 days	15 days	HK$97	HK$8.08
13 days	15 days	HK$97	HK$7.46
14 days	15 days	HK$97	HK$6.93
15 days	15 days	HK$97	HK$6.47

Two facts fall out of that table, and they are the ones worth remembering:

An 8, 9 or 10-day trip all cost HK$65. An 11 to 15-day trip all cost HK$97. If your itinerary is 9 days, you are paying HK$7.22 a day; the person on the same plan for 10 days pays HK$6.50. Nothing you can do about the trip length — but it means the marginal day is free, so if you are choosing between flying home on day 9 or day 10, the tenth day costs you nothing in data.

A two-day trip is the worst value on the ladder — HK$11.00 a day, which is more than a single day costs, because you are buying three days and using two. There is no clever way around that: the plan you would want does not exist. Either accept the HK$22, or buy the one-day plan and run the second day on hotel wifi.

The second gigabyte is the most expensive gigabyte

Data tiers are not priced evenly, and the unevenness is consistent across every length. This is what each extra gigabyte costs you:

Length	Going 1 → 2 GB/day	Going 2 → 5 GB/day
1 day	HK$3.00 per GB	HK$1.00 per GB
3 days	HK$2.33 per GB	HK$1.00 per GB
5 days	HK$2.40 per GB	HK$1.07 per GB
7 days	HK$2.29 per GB	HK$1.05 per GB
10 days	HK$2.40 per GB	HK$1.03 per GB
15 days	HK$2.33 per GB	HK$1.04 per GB

The second gigabyte costs more than twice what the third, fourth and fifth cost. So the 2 GB tier is the one tier that is almost never right: if you need more than a gigabyte a day you need noticeably more, and if you need less you should stay at 1 GB. On a seven-day trip, the jump from 1 GB to 5 GB is HK$38; from 1 GB to 2 GB is HK$16 for a fraction of the data.

Unlimited sits a flat HK$2.00–2.33 a day above the 5 GB tier — HK$16 more for a week, HK$35 more for fifteen days. That is cheap for what it is, and it is the tier to take if you plan to stream or upload photos daily. One caveat, stated plainly: this is a data-only plan and we do not advertise hotspot use on it, so if you intend to tether a laptop, ask support before you buy rather than after.

Midnight in Hong Kong is not midnight where you are

The activation policy on this plan reads: "The Calendar Day in TimeZone UTC+08:00 is applied on the validation date." In Singapore and Malaysia that is the same as local midnight, so nothing surprising happens. In Thailand and Vietnam — both UTC+7 — the allowance flips at 23:00 local time.

That produces one specific, expensive mistake. Land in Bangkok at 22:30 and your plan activates on arrival; thirty minutes later the counter rolls over to day two. On a three-day plan, you have just spent a third of your data days on half an hour in a taxi.

The fix is free: if you are landing in Thailand or Vietnam late in the evening, stay in airplane mode until after 23:00 local, then let the eSIM connect. You have 30 days from purchase to activate, so a few hours costs you nothing — and it buys you a full first day.

This is also why the 15-day ceiling matters. There is no 30-day version of this plan, so a three-week trip needs two plans regardless. Which leads to the one place where two plans genuinely beat one:

An eight-day trip: the 10-day plan is HK$65. A 7-day plan plus a 1-day plan is HK$56.
An 11-day trip: the 15-day plan is HK$97. A 10-day plan plus a 1-day plan is HK$74 — a saving of HK$23, or 24%.

The cost is not money, it is admin: two QR codes, two eSIM profiles in your phone, and a manual switch of your data line on the day one ends. If you are comfortable in Settings → Mobile Data, it is worth doing on any trip of 11 to 14 days. If you are not, pay the HK$23 and keep one profile.

What this plan does not give you

Three limits, all of them real:

No phone number. It is data only. You cannot receive an SMS or make a call on it. For most travellers that is fine — WhatsApp and Grab work over data — but some local services (a Thai delivery app, a bank that texts a code) want a local number, and no eSIM replaces that.

Your IP will most likely show Hong Kong. The APN is CMHK/CMLink, the same Hong Kong core our other plans use, so expect your connection to geolocate to Hong Kong rather than to the country you are standing in. That is usually harmless, occasionally useful, and occasionally confusing — a local streaming catalogue may not behave the way it does on a local SIM.

Four countries does not mean four local numbers, or four local prices. If you are spending two weeks in Thailand alone, a local SIM bought in a 7-Eleven is cheaper and comes with a Thai number. This plan wins on multi-country trips and short ones, not on single-country long stays.

One plan versus four SIMs, honestly

Four local SIMs cost less in sticker price than this plan at most stops. What they cost in everything else is what this plan is buying: four queue-and-register episodes at airports that price for people who have just landed, four top-ups in four currencies, and four numbers to juggle. This eSIM requires no identity registration at all — which is the single biggest difference from our Hong Kong plan, where real-name registration is mandatory and has to be finished before you land.

So: if your trip touches three or four of these countries and you would rather not spend an hour of each arrival at a counter, one plan is the right answer. If it is one country for a fortnight, buy local.

Where it sits next to our other plans

Same seven-day trip, three plans on the same shelf, all priced today:

7 days	Singapore · Malaysia · Thailand · Vietnam	Japan	Hong Kong
1 GB/day	HK$47	HK$55	not sold
2 GB/day	HK$63	HK$75	HK$49
5 GB/day	HK$85	HK$101	HK$69
Unlimited	HK$101	HK$121	HK$85

About 16% below Japan at every tier, and 19 to 29% above Hong Kong depending on the tier. That gap is not a pricing mistake: Hong Kong is one city, this is four countries. If you are weighing a Japan trip against a South-East Asia one, the Japan ladder works the same way — the same six-step arithmetic, different numbers.

And if you are only transiting Hong Kong on the way to these four, the one-day Hong Kong plan is HK$10 and covers a layover that crosses midnight, which this plan would charge you HK$22 for.