eSIM in the UK: Prices, the ETA and the Cheapest Brand

Two things about Britain are worth knowing before the phone gets packed, and neither is a tariff. You cannot board the plane without a permission that lives in an app, and every 3G network in the country has been switched off. The first decides when you buy connectivity. The second decides which handsets can use it at all.

The shelf itself is unusually tidy. Britain sells 230 plans, second only to the United States, and the same brand holds the cheapest plan at each of the six sizes between 1GB and 50GB. There is no tier at which switching produces a saving, so comparing brand against brand finds nothing. What is left is the spread inside each tier: the three sizes visitors actually buy, 5GB, 10GB and 20GB, run 3.9 times between the cheapest and the dearest brand, and a gigabyte costs $0.44 at the bottom of the range against $7.00 at the top.

All ten brands sell on EE, O2, Vodafone and Three, all four in every plan, so the network is not part of the decision either. An eSIM in the UK is therefore a price decision and a timing decision, and nothing more.

Every plan sits on the UK comparison table, with both rankings there to sort.

Do you need the ETA app before you fly?

Yes. Since 25 February 2026 the Electronic Travel Authorisation is checked at the gate, and the airline can refuse boarding without it. It is not a visa and it is not free: £20 since 8 April 2026, applied for through the official UK ETA app, valid for two years, and linked to the passport you travel on. Most decisions come back in minutes, and the government’s own advice is to allow three working days for the ones that do not.

One exemption is worth knowing if the trip is a connection. A traveller who stays airside at Heathrow or Manchester without passing through UK passport control does not currently need one. Everyone who clears the border does, including people changing planes.

That single rule changes the order of a trip. The application needs a phone, a camera for the passport page and an internet connection, and it has to happen before the flight rather than after it. Anyone who planned to sort connectivity on arrival has the sequence backwards.

The guidance on who needs one lists the 85 eligible nationalities, and British and Irish passport holders are exempt.

What does a UK eSIM cost and who is cheapest?

Five gigabytes, enough for a city week, starts at $4.00. Ten gigabytes costs $2.00 more at $6.00, twenty starts at $10.00, which is the size a two-week visit or a family sharing a hotspot actually needs, and fifty sits at $22.00. Flat-rate data for a month starts at $26.00, level with France for the cheapest unlimited month in this group, and a year of validity, 24GB across twelve months, starts at $19.00.

Each price is the lowest that any brand lists at that size, whatever window is attached to it, so a three-day plan can undercut a thirty-day one at the same size.

Roamic holds the first column at all six sizes, which is the finding the table exists to show. The third column is where the market gets narrow: from 3GB upward the runner-up is never more than a third above the leader — $3.99 against $3.00, $5.00 against $4.00, $7.99 against $6.00 — and 1GB is the single size where the second brand doubles the price, at $1.99 against $1.00.

At the other end the pattern is consistent enough to be a rule. Airalo is the dearest plan at five of the six sizes, from $12.00 for 3GB to $54.00 for 50GB, and Jetpac takes 1GB at $7.00. Across the metered shelf the top of the range is 15.9 times the bottom, $0.44 per gigabyte at the 50GB end against $7.00 at the 1GB end, which is why the size and the brand belong in the same decision rather than in sequence.

Unlimited deserves a warning before anyone upgrades to it. 102 of the 230 plans are flat-rate, and the gap between $26.00 for a month of unlimited and $10.00 for 20GB is only worth paying if the allowance would genuinely run out. The fair-use table shows what the flat-rate products do once the threshold is reached.

Holafly sells nothing but flat-rate plans, and its thirty-day product is $73.90, nearly three times Ubigi’s $26.00 for the same unlimited month. Anyone drawn to the words unlimited data should price those two before paying for the phrase.

The window is the part that catches a long trip. A seven-day product bought for ten days in Britain leaves three days leaning on hotel wifi, and a size up costs a couple of dollars while a size down costs a second purchase at a worse rate. Any of the ten brands puts you on all four networks, so price and window decide it, and nothing else does.

How much data does a week in Britain actually use?

Three gigabytes covers a week of maps, messaging, rail tickets and photo uploads, with room to spare. The British addition is ticketing: train tickets, event tickets and the contactless gate system all sit on the phone, and several of those apps keep a session open in the background all day.

A three-day city break needs less than half of that, and a ten-day visit should avoid a seven-day window, since the top-up at the end of the trip costs more than the size up at the start.

Add a hire car, a hotspot for a second traveller and photo backup, and a week clears 10GB. Because the three main sizes run the same multiple between brands, guessing wrong costs the same proportion at any of them, which makes the larger allowance the cheaper mistake. At the cheapest brand ten gigabytes is $6.00 and twenty is $10.00, so the second ten costs four dollars.

The data calculator turns an itinerary into a number for trips that do not fit the pattern.

Where do you buy a UK eSIM and when do you install it?

Buy it in the brand’s app or on its site, at home. A UK profile arrives from a QR code or from inside the provider’s app, and either route needs a connection at the moment it runs, which is the whole reason to do it where the wifi is not metered and nobody is queueing behind you. Installing and activating are separate events: the profile sits dormant on the phone for as long as you like, so doing it early costs nothing and doing it late gains nothing. Write the label the phone offers, and keep the code somewhere other than the inbox you might lose access to, because a profile deleted by accident has to be reissued and some brands charge for it.

The installation walkthrough covers both handsets step by step, and what an eSIM is is the page to send anyone still asking why there is no card left to lose.

Will your phone still make calls in the UK?

Yes, unless the handset depends on 3G. Those networks are gone, and the timetable was staggered. EE and Vodafone went first in February 2024, Three followed at the end of November 2025 and O2 in the opening weeks of 2026, with the regulator confirming completion in May 2026. 2G remains for now, with EE planning to start closing it in May 2029 and the rest following by 2033.

The consequence is narrower and sharper than it sounds. A phone that can carry voice over 4G is unaffected. A phone that cannot has nowhere to go: the setting is VoLTE, sometimes labelled 4G calling, and most handsets sold since 2015 support it. It is a toggle rather than a guarantee, and a handset that has never had it switched on will still fail a call.

One further British detail matters for a visitor specifically. O2 stopped letting inbound roamers onto its 2G network in October 2025, so a travel eSIM on that network has no 2G fallback even where a British phone still does. The handset check is therefore not a formality. The compatibility page covers the models, including the regional variants that leave the eSIM out.

Does a UK eSIM work in London?

The same product covers the whole country, and London is where the four networks are at their densest, so a London eSIM is the same file at the same price as one for Manchester or Edinburgh, and anyone shopping for an eSIM for London is really shopping for a UK plan. What the capital draws on is not the sightseeing but the transit: a long weekend of maps, platform changes and ticket apps fits inside 5GB at $4.00.

The exceptions are the Underground and the fare gates, and neither behaves the way the rest of the city does.

Does contactless need a UK number or a data session?

No. Transport for London takes any contactless bank card and any phone wallet, whatever country issued them, and a gate opens without the phone being online. What it does require is consistency: the same card or the same device touched in and touched out. Tapping in with a physical card and out with the phone that shares its wallet registers two incomplete journeys and charges two maximum fares, which in zones one to six runs to £9.40 each.

Is there signal on the London Underground?

More than there used to be, and less than the posters suggest. By the autumn of 2026 roughly 60 per cent of the 121 below-ground stations carried 4G and 5G, the Elizabeth line was covered end to end, and the rest were due by the end of the year, with the Victoria, Jubilee, Bakerloo and Piccadilly lines and the last Circle and District sections still being worked through. A single shared network serves all four operators, so the brand on your phone does not change the answer.

The catch is how coverage arrives: tunnel section by tunnel section rather than line by line. A call that drops between two stations has crossed into a stretch that is not finished, which is why the same line can work on one journey and fail on the next. Transport for London publishes a live map of what is connected, and it changes every few weeks.

Route on the Elizabeth line where a connection matters. For everything else, download the map and the ticket before going underground, because a phone with no signal still cannot load a platform number.

Is a Heathrow starter pack cheaper than an eSIM?

No. Heathrow’s starter packs run £20 to £30 for an allowance a mid-size eSIM covers at $10.00, and a supermarket in town sells the same thing for less. There is no identity check to slow it down, so the counter is quick, and what it does sell is a British number. Anyone who needs one for a booking, a delivery or a code has a reason to queue, and everyone else does not.

Do you need a UK phone number?

A data-only eSIM has no number, and most trips never notice. Maps, messages, rail tickets, event tickets, the contactless gates and every ride-hailing app work on a profile with no number at all.

Four things do need one: a restaurant that takes bookings only by telephone, a hotel that texts a door code, a delivery that needs a local contact before it leaves the depot, and a bank sending a six-digit verification code. The last is the one people underestimate, because no amount of data fixes it.

The arrangement most visitors end up with keeps the home line live for the codes and puts the data on the eSIM, which is what dual SIM exists for.

Anyone who genuinely wants a UK number has a second product to buy. All four networks sell a prepaid eSIM that comes with one — EE, Vodafone, O2 and Three — and so do the smaller brands built on them, among them giffgaff, VOXI, SMARTY and Lycamobile. Lebara’s eSIM rollout is restricted enough that it is worth checking before counting on it. The friction sits at checkout rather than on the shelf: the same fraud filters that decline a travel purchase decline a network’s own, and a prepaid product is built around a British billing cycle rather than a two-week visit. It is a different purchase, and it is the only route to a number.

Does a UK eSIM work in Ireland and Europe?

No. A UK-only plan stops at the water. A UK-only product names the United Kingdom and nothing across it, so the Dublin ferry or the Eurostar arrives with a phone that has no session.

Ireland is the case that surprises people, because the border is invisible on the ground. There are no routine immigration checks on the land border between Ireland and Northern Ireland, and a traveller can cross it without showing a passport at all. The product boundary is not the same line as the immigration one, and the phone drops off the moment the mast changes country.

That is what followed the UK’s departure from the European roaming area, and it runs in both directions. A British line crossing into Europe can be charged again, and a European line visiting Britain no longer roams at its home rate by right. The European Union’s roaming rules attach to lines issued in the EEA rather than to British ones.

For a trip that is Britain alone, a UK plan is the cheaper buy, since a regional bundle charges for coverage that will not be used. The arithmetic only turns when the trip crosses a border: one regional plan that names both countries usually costs less than two national plans bought separately, and the country list on the plan page is the thing to read rather than the headline. A Britain and Italy trip is the common version of that, and the Europe coverage breakdown lists which bundles name both. The Ireland table prices the Irish leg on its own.

Will your card work at checkout?

Almost always yes. Visa and Mastercard are accepted by every brand, so a refusal is almost always the issuing bank rather than the brand.

The pattern that fails is predictable: a first charge to an unknown merchant in a foreign currency, made from an airport, at a moment when a fraud filter is watching. It clears if the bank has been told, or if the charge is approved in the banking app as it arrives, or if the payment goes through a wallet rather than a typed number.

Two failures are worth avoiding by design. Retrying a declined card is counterproductive, because the second decline usually locks that merchant for that card and the third attempt never reaches the brand. And a card with a low overseas limit will fail on a year-long plan where it would have succeeded on a week.

The prices here are listed in US dollars by the brands themselves. A euro or sterling card is converted at the issuer’s rate, which is noise compared with picking the wrong size.

Can you cancel a UK eSIM within 14 days?

Yes, if it has not been installed, and the right comes from the Consumer Contracts Regulations rather than from the seller’s goodwill.

The 14 days run from delivery, which for an eSIM is the day the code arrives by email. A cancellation inside that window on an uninstalled profile is refundable in full.

The exception is the one that matters. Digital content supplied immediately loses the withdrawal right once the download has begun, and a seller who asks for consent at checkout is relying on exactly that. An installed profile ends the argument.

The UK sits outside the European roaming area, which is a separate question with a separate answer and does not touch the cancellation right, because that is domestic consumer law.

The regulations still apply in England, Wales, Scotland and Northern Ireland, and a seller based abroad is bound by them when selling to a UK consumer. Enforcing across a border is the hard part rather than the right.

The practical version is to order, wait, and install a day before the flight. A trip cancelled inside the window is then a refund rather than a dispute.