Best SIM deals on Three: 25GB for £7, 60GB for £9
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We show you the best choices in Three's SIM only range this month, after comparing them against every other network. Last updated: 29th September 2025.
Three's best SIM only deals
Our favourite SIM only deal of the month on Three
just
£7
a month
✔ Unlimited mins and 25GB data See full deal
at three.co.uk
(opens in new window)
We think the best value for money SIM only plan on Three for September is their discounted 25GB for £16 £7 deal. It's on a 12‑month plan and comes with unlimited minutes and texts too:
That’s £108 you’ll save over 12 months with the deal thanks to the £9 monthly discount.
It's a good deal by Three's standards but price-wise you can still beat this plan on other providers (even ones that still use the Three network). Here are the networks offering it cheaper:
They're also offering 60GB for £9 on SIM only currently
just
£9
a month
✔ Unlimited mins and 60GB data See full deal
at three.co.uk
(opens in new window)
For people who need more data, the next best SIM only plan on Three in our opinion is their discounted 12‑month one below. For £16 £9 a month, you get 60GB data, plus unlimited minutes and texts:
That means a total saving of £84 when you add up the £7 discount over 12 months.
If you're open to joining other networks than Three, you can actually get a similar deal for less, even with providers whose SIMs also use the Three network. See the networks that beat it here:
£12 for 120GB is Three's next best SIM deal in September
just
£12
a month
✔ Unlimited mins and 120GB data See full deal
at three.co.uk
(opens in new window)
If you want even more data, another good deal on Three at the moment is their discounted £18 £12 SIM only plan here, which includes 120GB data instead, plus unlimited minutes and texts:
In total, that discount of £6 a month means you’re looking at a saving of £72 over the 12‑month deal.
While it's good enough to be in our pick of Three's best SIM only deals, other providers do still have similar plans for less, even ones that also use the Three network. Here are the networks where it'd cost less:
There's also a nice unlimited data for £18 plan with them this month
just
£18
a month
✔ Unlimited mins and unlimited data See full deal
at three.co.uk
(opens in new window)
For even more data, our next best pick of Three SIM only plans is their discounted 12‑month £28 £18 deal below, which gets you unlimited data and unlimited minutes and texts:
Getting £10 off a month means you’ll save £120 over the course of your 12‑month deal.
It's definitely one of Three's best. But it's not market-leading. You can get a similar plan on other providers for less, even if you need your SIM to use the Three network. See which networks that are cheaper here:
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How Three compare on SIM only prices and benefits
We said in our full review of the Three network that our favourite thing about them is their fast 4G and 5G speeds as well as their encouraging 5G coverage.
On SIM only you can take a 1-month, 12-month or 24-month contract. Typically the longer the contract, the lower your monthly cost. But it’s always worth shopping around to find their best current deal.
Three’s “Lite” plans are much cheaper than the sorts of deals you’d get on other main networks. Three also have some premium plans with extra benefits baked in. You can take these on 12 or 24-month contracts.
All Three plans give you access to their handy Three+ rewards app. And you get EU and worldwide roaming passes included on their premium Value and Complete plans, as well as these other benefits.
Useful link: Read our full Three review
Other good things to know about Three’s SIM only plans
Three will send your SIM card within 3-5 working days. You’ll receive a package with every size of SIM in it, so you can fit your SIM into every phone. Three also offer eSIMs (see more info here).
You can return your SIM within 14 days to get a full refund if you’re not satisfied. Returning things you bought in a Three store is a bit more tricky, so read the full terms and conditions here to learn more.
To join on any Three SIM only contract you’ll have to pass a credit check. If you were rejected for a contract on Three then you can either take a monthly PAYG bundle or top up with credit and pay as you go.
If you want to keep your number when switching to Three from another network, you can do so by requesting a PAC from your old provider and giving it to Three at any time. Here’s their guide on how to do this.
Useful link: Compare all Three SIMs