Prepaid mobile plans in the UK are a great way to keep your mobile data costs under control. You won’t get any nasty surprises and you’re not tied into a long-term contract that stops you switching to a better deal when it comes along.

UK SIM cards heathrow
Photo by Felix Wilson

What’s the difference between prepaid, pay-as-you-go, and regular contracts?

Prepaid plans sit in the middle between pay-as-you-go (PAYG) and regular monthly contracts (sometimes just called post-paid). PAYG and prepaid are similar in that in both cases, you pay for the data before you use it.

With PAYG, you need to buy top-ups once you’ve used up your data or the data has expired. With prepaid, you can cancel at any time, switch to a different plan, or continue with your existing plan but you need a payment method such as credit card or debit card.

Regular monthly contracts are post-paid and have cancellation fees if you want to get out early. They also require a credit check and for you to jump through a few hoops when you sign up.

Looking for a monthly contract rather than prepaid? Most of the prepaid carriers can also be used long term, but if you’re certain of your needs and you’re not going anywhere anytime soon, it’s well worth checking out our post on longer-term UK mobile contracts.

SIM compatibility

Unless your mobile phone is positively ancient, the correct type of SIM card will be what’s called a “nano SIM”. Even if your phone is a relic from the past, you’ll be fine as the big carriers all sell “trio SIMs”, which means no matter which one you buy, it will fit in your phone. Most modern handsets work on multiple bands, but if you’re unsure, check Will my phone work? to see which providers will work with your handset.

And if you’re set on getting a 5G SIM for your shiny new 5G compatible handset, or just 5G curious, take a look at our guide to what 5G is and where to get a SIM.

A trio SIM from Three. | Photo by Gregory Lane

UK prepaid SIM card options

The UK has plenty of mobile carriers and a healthily competitive market, which means you can get pretty good prepaid deals.

Here’s a non-exhaustive list of your prepaid UK SIM card options. For more details, check each carrier’s site.

Note: SMARTY, the hugely popular VOXI, and GiffGaff are strong contenders for the prime spot, and often have special offers.

VOXI offers a contract-free, rolling monthly deal with “endless social data”, allowing unlimited use of social apps without touching your data. They have a similar “endless video” feature. A sub-network of Vodafone, VOXI is the first UK SIM provider offering a 5G-enabled unlimited data option.

Comparing SIM data packages

Data Price Talk(min) / Texts 5G ready Link
30GB £10.00 Unlimited / Unlimited No More info
50GB £12.00 Unlimited / Unlimited No More info
Unlimited £18.00 Unlimited / Unlimited No More info

Data Price Talk(min) / Texts 5G ready Link
6GB £10.00 Unlimited / Unlimited No More info
12GB £12.00 (with endless video) Unlimited / Unlimited Yes More info
15GB £15.00 (with endless video) Unlimited / Unlimited Yes More info
45GB £20.00 (with endless video) Unlimited / Unlimited Yes More info
Unlimited £35.00 Unlimited / Unlimited Yes More info

Data Price Talk(min) / Texts 5G ready Link
2GB £8.00 Unlimited / Unlimited No More info
6GB £10.00 Unlimited / Unlimited No More info
10GB £12.00 Unlimited / Unlimited No More info
15GB £15.00 Unlimited / Unlimited No More info
80GB £20.00 Unlimited / Unlimited No More info
Unlimited £35.00 Unlimited / Unlimited No More info


Data Price Talk(min) / Texts 5G ready Link
2.5GB £6.00 Unlimited / Unlimited No More info
7GB £8.00 Unlimited / Unlimited No More info
10GB £10.00 Unlimited / Unlimited No More info

Tesco Mobile
Data Price Talk(min) / Texts 5G ready Link
12GB £10.00 5000 / 5000 Yes More info

Data Price Talk(min) / Texts 5G ready Link
4GB £16.00 Unlimited / Unlimited Yes More info
12GB £19.00 Unlimited / Unlimited Yes More info
30GB £24.00 Unlimited / Unlimited Yes More info
Unlimited £26.00 Unlimited / Unlimited Yes More info

Note: Some packages may allow for data rollover.

Where are the major carriers like O2, EE and Vodafone?

If you’re wondering why the major carriers like O2, EE and Vodafone aren’t here, it’s because they don’t offer one-month prepaid plans. They offer pay-as-you-go SIMs and longer term, post-paid mobile contracts. Some of the virtual network providers above are subsidiaries of big operators, though. For example, VOXI is a subsidiary of Vodafone, and Plusnet operates on the EE network.

Unlocking mobile phones in the UK

From December 2021, mobile carriers in the UK will be banned from selling locked cell phones. While they’ve had to unlock phones on request for many years now, they’ve still been allowed to sell them locked. Having access to an unlocked phone from the get-go can be a money-saver, as it makes it easier to switch providers.

Information on SIMs for travellers to the UK

Travelling without constant data these days is almost unthinkable. Getting from the station to your accommodation? You’re probably going to want to follow that little blue dot on the screen all the way to your bed for the night. Luckily, getting a good-value prepaid/pay-as-you-go UK SIM card is easy.

Just arrived? Keep calm and use wifi

The good news about London is that pretty much everywhere you go there’ll be some kind of open wifi network, starting with the airport. Don’t be tempted to get a PAYG UK SIM at the airport, because there’s a good chance it won’t be the best deal available. Rather order online, or wait a bit.

Do I even need a UK SIM card?

If you’re lucky enough to be an EU resident, or you started your trip in an EU country, even post-Brexit, Brussels has you covered; you can roam for free in London. Things might change after January 1, 2021, when the transition window for Brexit closes. The official chance is that this won’t change—but it’s worth watching this space—we live in uncertain times!

Increasingly, non-EU mobile providers are also offering free or discounted roaming. For example, if you’re in the US on T-Mobile, free international roaming is included with “ONE”, “Magenta”, “Simple Choice”, “New Classic” or “Select Choice” plans. Others offer low per-day roaming costs. Sometimes these roaming plans require pre-activation, so check with your mobile company before you travel.

Even if your plan does include international roaming, you might want to check the fine print—or just test performance after you arrive. Some plans are restricted to 2G data speeds (for example T-Mobile is restricted to 128Kb/s!), so getting a UK SIM might still be worth it.

How much data do you need?

As long as you log in to wifi when available, you probably won’t use much more data than you use at home. If you go on a data diet, you might be able to keep yourself to 100Mb/day or less, but personally I like to have a comfortable buffer of data for those situations when you need to know if the last train is leaving from your closest station in the next five minutes.

While we do our best to make sure the information in this post is correct, prices and other details are subject to change. This post was originally published on July 12, 2017. Last updated December 4, 2020.

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