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Best unlimited data SIM 2024: Compare bargains from the top mobile networks, based on our annual customer survey

Sick of running out of data? These are the best unlimited data SIM plans as determined by our survey of the leading networks’ customers

The best unlimited data SIM plans from the top mobile networks will give you peace of mind when you’re scrolling through the news on the train, running along to Spotify or finding the perfect restaurant on holiday. Slot one into your phone and you will never be caught short, but which one should you pick?

You shouldn’t simply buy the first unlimited data SIM you come across: there are lots of important factors to keep in mind, including the length of the contract, value for money, performance, coverage and whether the price includes any extras.

To help, I’ve put together a list of the best unlimited data SIM-only deals based on the results of the latest Expert Reviews Mobile Network Awards survey, which had over 4,000 respondents. And, if you’re not sure where to start, I’ve also compiled a handy buying guide that answers the most important questions. Surf’s up.

Get a brilliant unlimited SIM plan from award-winning Smarty

If you’re fast, you can pick up this excellent SIM-only deal from Expert Review Recommended award-winning mobile network Smarty: unlimited 5G data for just £16/mth on a rolling, 30-day plan. That’s a whopping 20% down from its normal £20/mth, but time is of the essence because offers this good don’t last for long.


Best unlimited data SIM: At a glance

Best dealSmartyView deal at Smarty
Best for speedEEView deal at EE
Best long-term planiD MobileView deal at iD Mobile
Best for calling abroadLebaraView deal at Lebara

The best unlimited data SIMs you can buy in 2024

1. Smarty: Best unlimited data SIM deal

Price: £16/mth, was £20/mth | View deal at Smarty

Smarty SIM card on a wooden table

DataUnlimited
Unlimited calls/textsYes
Plan length30 days
Percentage of existing customers who would recommend Smarty*92%
Last reviewed by Expert ReviewsNovember 2023

*According to the Expert Reviews 2023 Mobile Network Awards survey

Benefits: Smarty may have been usurped by Voxi in our latest Mobile Network Awards, but it still finished in second place overall and remains the best unlimited data SIM money can buy. In our four-star Smarty review, expert Stuart Andrews praised the low-cost plans, top 5G performance, free EU roaming up to 12GB and solid customer service results of the mobile virtual network operator (MVNO), which runs on Three’s network.

A gigantic 92% of those we surveyed would recommend Smarty to a friend or family member and I’m more than happy to do the same. And now is a perfect time because the company has slashed the price of its unlimited deal by 20% to £16/mth on a rolling, 30-plan, down from the usual £20/mth.

Drawbacks: The only gnat in the ointment was a fall in Smarty’s customer service satisfaction rate compared to the year before, from a huge 83% to 63%. It isn’t alone in this, however, and many of its rivals are sitting on a similar percentage.

Read our full Smarty review

View deal at Smarty

2. EE: The best unlimited data SIM for speed

Price: £35/mth | View deal at EE

SIM card with the logo of the mobile network EE

DataUnlimited
Unlimited calls/textsYes
Plan length30 days
Percentage of existing customers who would recommend EE*69%
Last reviewed by Expert ReviewsNovember 2023

*According to the Expert Reviews 2023 Mobile Network Awards survey

Benefits: Picking up four stars out of five in our most recent EE review, the Kevin Bacon-toting mobile network impresses with its screamingly fast download speeds – still the speediest in the country after ten years – wide coverage, good customer service scores in our yearly Mobile Network Awards and a raft of extras.

EE’s best unlimited data SIM deal isn’t cheap at £35/mth on a rolling, one-month plan, but you’re paying a premium for what is essentially the Ferrari of mobile networks. According to the latest round of RootMetrics testing, its median 5G and 4G download speed was 61Mbits/sec, which is a country mile ahead of silver medallist Three’s 38Mbits/sec.

Drawbacks: I can’t deny that EE is expensive and you can find more cost-effective offers lower down this list. You can lower the monthly price by signing up for a longer contract, but keep in mind that EE is one of the networks that has opted to increase prices mid-contract every spring by the Consumer Price Index (CPI) rate of inflation plus an extra 3.9%.

Read our full EE review

View deal at EE

3. iD Mobile: The best long-term unlimited data SIM plan

Price: £8/mth for 6 months, then £16/mth | View deal at iD Mobile

An iD Mobile SIM on a wooden table

DataUnlimited
Unlimited calls/textsYes
Plan length24 months
Percentage of existing customers who would recommend iD Mobile*79%
Last reviewed by Expert ReviewsNovember 2023

*According to the Expert Reviews 2023 Mobile Network Awards survey

Benefits: Unlike lots of its rivals, iD Mobile has decided not to introduce mid-contract price hikes, making it our pick of the networks if you’re after a longer-term deal. An MVNO running on Three, it’s an excellent choice if you’re after unlimited data without breaking the bank. In our most recent iD Mobile review, we awarded it four stars out of a possible five for its attention-grabbing deals, decent 5G performance and coverage, data rollover feature and free roaming in the EU up to 30GB.

The network is currently serving up unlimited 5G SIM-only data for just £8/mth for the first six months of a two-year plan. The price will then rise to a still-attractive £16/mth for the remainder of the contract, but make sure you get in there quickly because this half-price deal is unlikely to last for long.

Drawbacks: Customer service is a sticking point with iD Mobile. As Stuart Andrews explained in our full review: “Just 17% of customers told us they were very satisfied with iD Mobile here, with an additional 36% fairly satisfied”. That total of 53% puts it behind the other providers on this list.

Read our full iD Mobile review

View deal at iD Mobile

4. Lebara: The best unlimited data SIM for calling abroad

Price: £25/mth | View deal at Lebara

A blue Lebara SIM card on a wooden table

DataUnlimited
Unlimited calls/textsYes
Plan length30 days
Percentage of existing customers who would recommend Lebara*87%
Last reviewed by Expert ReviewsNovember 2023

*According to the Expert Reviews 2023 Mobile Network Awards survey

Benefits: Lebara is an MVNO that runs on Vodafone’s network and a brilliant choice for calling friends or family abroad thanks to its bundling of international minutes. That’s why we gave it four out of five stars and a Recommended award in our full-length Lebara review.

This is my pick of the Lebara unlimited plans at the moment: if you sign up for the 30-day, rolling £25/mth option, you will get 100 minutes when calling 41 countries around the world, including India, the US, China, Australia, New Zealand, Thailand, Malaysia, Canada, Hong Kong and South Korea. What’s more, you’ll be able to roam for free in both the EU and India, up to a fair use limit of 30GB.

Drawbacks: As with other networks on this list, the main downside was Lebara’s customer service scores in our annual Mobile Network Awards survey, with just over 50% of respondents telling us that they were satisfied with the support they received. That was one of the lowest scores across the entire survey.

Read our full Lebara review

View deal at Lebara

5. Voxi: The best unlimited data SIM for social media and streaming

Price: £15/mth | View deal at Voxi

Black Voxi SIM card on a wooden table

Data90GB, plus unlimited use of social media, video and music apps
Unlimited calls/textsYes
Plan length30 days
Percentage of existing customers who would recommend Voxi*92%
Last reviewed by Expert ReviewsNovember 2023

*According to the Expert Reviews 2023 Mobile Network Awards survey

Benefits: Voxi is our favourite mobile network overall, receiving five stars out of five and an Expert Reviews Best Buy award in our latest in-depth Voxi review. SIM plans like this are why: for £15/mth on a rolling, 30-day plan, you’ll get 90GB (was 30GB) of 5G-compatible data plus unlimited usage of social media, video and music apps such as Instagram, TikTok, Twitter, Facebook, YouTube, Netflix, Spotify and Apple Music. That’s extraordinary value for money, especially if you spend a lot of time on those apps.

In our write-up of Voxi, we praised the Vodafone-powered MVNO for its dazzling unlimited bonuses, fuss-free plans, rock-solid reliability and consistently high performance. No wonder it also scooped the top prize in the annual Expert Reviews Mobile Network Awards, as well as silverware in the Best Value and Most Reliable categories.

Drawbacks: The only real thorn in Voxi’s side is a lack of free EU roaming, with customers paying £2.25/day to access 20GB of data in the EU.

Read our full Voxi review

View deal at Voxi

Why are other mobile networks not on the list?

There are a few household names missing from my list above but with good reason. In short, the reviews we gave them weren’t good enough to justify their inclusion. Below, I’ve rounded up a short explanation about why each of them was left out, complete with links to our full reviews.

1. Three: Lacklustre customer service

Three’s 5G performance and coverage results might have been good in our annual Mobile Network Awards survey, but it only received three stars out of five in our review due to its mediocre customer service feedback.

Read our full Three review

View deals at Three

2. Vodafone: So-so performance

Vodafone also picked up a three-star rating in our review. While its bargain bundles certainly have the power to turn heads, it was let down by middling performance scores, below-average customer service and EU roaming charges.

Read our full Vodafone review

View deals at Vodafone

3. O2: Too expensive

O2 does do some things well, such as offering free roaming in the EU up to a fair use limit of 25GB, but it still received three stars out of five due to speeds that lag behind its rivals, low customer service scores and high prices.

Read our full O2 review

View deals at O2

How do I find the best unlimited data SIM plans?

As Expert Reviews’ deals editor, there’s nothing I enjoy more than tracking down deals that will save you money without compromising on quality. A lot of thought, time and effort is involved in the process, but I’ve briefly summarised my methods below and you can find out more details in my article about how I source deals.

How good is the mobile network?

I bring together experts to produce in-depth reviews based on their years of mobile network-watching experience. That means every unlimited data SIM plan will be based on the latest in-depth review, along with the results of the Expert Reviews Mobile Network Awards customer survey. If a mobile network isn’t as good as the others or it hasn’t been reviewed yet, its plans won’t be recommended.

Is there something for everyone?

I realise that people have very different budgets, especially during a cost of living crisis. That means I’ll always make sure that there’s a worthwhile, budget-friendly plan in a roundup. That said, I won’t just recommend something because it’s cheap as you might end up having to pay more in the long run if the performance isn’t adequate.

Are there any hidden catches?

It can still be easy to stumble into a costly trap such as the new mid-contract price hikes, which see networks increasing prices by a set amount every year (usually the Consumer Price Index rate of inflation plus an extra 3.9%).

Wherever possible, I’ll avoid recommending any deal that will become more expensive as time passes. However, if one does make the list, I’ll always be transparent in the mini-review and justify its inclusion.


How to choose the best unlimited data SIM for you

How much should you spend?

Prices for an unlimited SIM can vary wildly depending on the length of the contract and additional features you’re getting. As a rule of thumb, though, we would hesitate to pay more than £30/mth for an all-you-can-use 5G SIM on a two-year plan. Anything under £20/mth might seem like a bargain, but you could be sacrificing speed or coverage so be sure to check the small print.

Third-party sites such as Affordable Mobiles and Mobiles.co.uk can offer eye-catching savings on SIMs, though you will often have to claim back the money via cashback after a set period. If you don’t mind the bit of extra paperwork, go for it, but it’s always worth checking the network’s site beforehand to make sure you’re not missing out on goodies.

How long should the contract be?

You can normally pick between a one-month, 12-month or 24-month unlimited SIM contract. We would opt for a two-year plan because that’s how you can get the most browsing bang for your buck. The shorter contracts, meanwhile, will appeal to users who don’t want to be tied down for so long.

Does download speed matter?

Most mobile networks, with the notable exception of Vodafone, don’t specify a separate speed for their unlimited data SIM and include a flat rate across all of their plans. We’ve mentioned the most recent Opensignal 4G and 5G download speed results in the bite-size reviews above.

Is it worth getting a 5G-capable SIM?

5G has already been rolled out across dozens of towns in the UK, but huge swathes of the country still aren’t covered. Consequently, it’s worth checking if you’re able to get the fastest speeds before you make a buying decision – there’s no point paying for a service that you can’t access. That said, you will find that many of the best unlimited data SIMs are now 5G by default.

Will you be able to use the SIM abroad?

Most of the leading mobile networks will offer some kind of scheme for using your SIM on your travels. Some opt for a daily data cap, while others let you use your entire allowance as usual. If there’s a particularly holiday-friendly extra available, it will be mentioned in our reviews.

What extras should you look out for?

All unlimited data SIM plans come with endless minutes and texts as standard, but networks also try to stand out from the crowd by throwing in useful tools such as personal hotspots or treats like money off subscription services. We’ve mentioned any permanent extras in our reviews, but it’s worth perusing our list of the best time-limited SIM-only deals too.

Read more

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