Smarty
Smarty Unlimited SIM
1 months
contract
£16.00
/month
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mobile / sim comparison
comparing 11 mobile and SIM-only deals across all major UK networks.
✨ not sure? help me choosethe order can be nudged by commercial deals - but never enough to bury a better one. want to be sure? sort by price or rating any time.
filter deals
nothing matches all of that. try loosening a filter - here's what's closest.
Lebara
Lebara 5GB SIM
5.00 GB
data
1 months
contract
£6.90
/month
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giffgaff
giffgaff 15GB SIM
15.00 GB
data
1 months
contract
£10.00
/month
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Sky Mobile
Sky Mobile 10GB SIM
10.00 GB
data
1 months
contract
£10.00
/month
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Three
Three Unlimited SIM
sponsored12 months
contract
£18.00
/month
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Voxi
Voxi 20GB SIM
sponsored20.00 GB
data
1 months
contract
£12.00
/month
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iD Mobile
iD Mobile 50GB SIM
sponsored50.00 GB
data
1 months
contract
£12.99
/month
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Tesco Mobile
Tesco Mobile 30GB SIM
sponsored30.00 GB
data
12 months
contract
£13.50
/month
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EE
EE Unlimited SIM
sponsored24 months
contract
£22.00
/month
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Vodafone
Vodafone 30GB SIM
sponsored30.00 GB
data
24 months
contract
£15.00
/month
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O2
O2 100GB SIM
sponsored100.00 GB
data
12 months
contract
£18.00
/month
go to deal »
prices change - confirm the final price on the provider's site.
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how to choose a SIM deal
Buy the data you use, not the data you fear running out of.
Most people overestimate. On wifi at home and work, even "heavy" users often need less than they think. Rough guide: light (mostly wifi, light browsing) 1–5GB · medium (maps, social, some video out and about) 10–30GB · heavy (lots of streaming on the move, hotspotting) 50GB+ or unlimited. If you're forever near wifi, a giant data bundle is money you're donating to your network.
Understand who actually runs your signal.
The UK now has three network groups that own the masts: EE, Virgin Media O2, and VodafoneThree (Vodafone and Three merged in 2025, though they're still sold as separate brands while networks combine). Everyone else - giffgaff, SMARTY, Tesco Mobile, VOXI, iD, Lebara and the rest - is an MVNO riding one of those networks. So a cheap MVNO can give you the same coverage as the big-name network it runs on, for less. Check which network a SIM uses, then check that network's coverage where you live and work.
Rolling vs contract.
A rolling 30-day SIM lets you leave whenever - great if you might switch or want to chase deals. A 12-month SIM is often a bit cheaper per month but ties you in. There's rarely a good reason to go longer than 12 months on a SIM-only.
The mid-contract price rise applies here too.
Same rule as broadband: since January 2025, any in-contract rise must be shown in pounds and pence upfront, not tied to inflation. Rolling SIMs sidestep the issue entirely - another point in their favour.
5G: nice, not essential.
Most modern SIMs include 5G where there's coverage. It's genuinely faster, but if your phone or area doesn't do 5G, don't pay extra chasing it.
what to watch for
- "Unlimited" small print - some have fair-use caps or slower speeds after a threshold.
- Roaming charges - EU roaming isn't always free post-Brexit; check if you travel.
- The mid-contract rise - shown in £/p now; rolling SIMs avoid it.
- Long contracts on a SIM alone - rarely worth it; 12 months max is the norm.
- Perks you won't use - data rollover, free subscriptions: nice if you'll use them, irrelevant if not.
faqs
How much data do I really need?
If you're on wifi most of the day, 5–15GB usually covers maps, messaging and a bit of video out and about. Go to 30GB+ or unlimited only if you stream or hotspot heavily away from wifi. Check your current usage in your phone settings before paying for more.
What's an MVNO, and is the coverage worse?
An MVNO is a brand that rents space on a big network's masts - giffgaff on O2, SMARTY on Three, and so on. Coverage is generally the same as the host network, often for less money. The trade-offs are usually around customer service and occasional data "priority", not signal.
Which network has the best coverage?
It depends entirely on where you are - there's no single winner. Check each network's coverage map for your home, work and commute, then pick a SIM (or an MVNO) on whichever network wins for you.
Will my price go up mid-contract?
On a fixed-term SIM, possibly - but since January 2025 it must be stated in pounds and pence before you sign. A rolling 30-day SIM avoids mid-contract rises altogether, since you can leave any time.
Can I keep my number?
Yes. Ask your old provider for a PAC code (text "PAC" to 65075) and give it to your new one - your number moves across, usually within a day.
Is it really free to use? How do you make money?
Free, no data taken. If you click through and take a SIM, the provider may pay us commission - and it never buys a higher ranking. Sort by price or rating any time to check the order yourself.