billshock.co.uk
For UK travellers · updated August 2026

Your phone might be the priciest thing you pack.

Roam, and you pay your network's daily rate whether you use it or not. Buy a travel eSIM, and you pay for data. Which one stings less depends on your plan, your trip and your habits — so this works it out with your numbers instead of a stranger's.

4 days, 2GBRoaming usually wins. Not worth the faff of switching.
2 weeks, 10GBClose call. Depends entirely on your daily rate.
A month, or long-hauleSIM, almost always. Daily fees compound brutally.
Step 1 — your network
How to find your exact rate

Step 2 — your roaming terms
Only bites if you exceed the cap. Around £3 is typical, but check yours.
Step 3 — your trip
Most travel eSIMs sell data, not a phone number. WhatsApp and FaceTime work; a call to your UK mobile won't reach you.
Around £1–2/GB for Europe, more for long-haul and for very small bundles.
The answer

Roaming

Travel eSIM

Your figures, our arithmetic. Nothing here is stored or sent anywhere. Always confirm charges with your own network before you travel.

Why every site gives you a different number

Your contract date matters

Most networks reintroduced European charges on a specific date and left older contracts alone. Two people on the same network and the same tariff can pay different amounts depending on when they signed.

Plan tier changes everything

Premium plans often bundle roaming that cheaper plans charge for. Pay-as-you-go is usually a separate scheme again, with its own daily and weekly rates.

Destinations are zoned

Networks split the world into zones, and the same trip can cost nothing, a couple of pounds a day, or seven, depending which zone your destination sits in. Ireland is frequently free when the rest of Europe isn't.

Can't check right now? Start here

NetworkEuropeFair-use capBeyond Europe
EEAround £2.47–£2.59/day; monthly pass available50GB (25GB PAYG)Zone-based passes
VodafoneAround £2.42/day; Ireland, Iceland and Norway free25GBAround £7.39/day
O2Included on most plans25GBAround £7/day
ThreeGo Roam, varies by plan12GBVaries by plan
giffgaff, SMARTY, iD, Tesco, VOXIGenerally included5–30GBUsually not included

These are typical figures, not promises. Premium plans, older contracts and business tariffs all differ. Use step one above to check yours properly — it takes about two minutes and it's the difference between an estimate and an answer.

The three ways people get stung

The daily fee triggers itself

On daily-charge networks the fee lands the moment your phone touches a foreign mast. One glance at a map counts as a full day, and a stopover can cost you a day in a country you never left the airport of.

Included roaming still has a ceiling

Every inclusive deal carries a fair-use cap. Past it you pay by the gigabyte at rates that make the daily-fee networks look kind. Know your cap before you start streaming.

An eSIM can't ring people

Travel eSIMs sell data, not a number. If you need to take a call on your UK mobile, keep roaming switched on for calls and let the eSIM carry the data. Both at once is often the cheapest setup.

Where to buy a travel eSIM

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Network guides