Three's best SIM only deals: 40GB for £8, 80GB for £10
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We've looked at SIM only on all UK networks to help you find out which of Three's plans work out best, for every data requirement. Last updated: 13th March 2026.
Three's best SIM only deals
Our favourite current Three SIM only deal
just
£8
a month
✔ Unlimited mins and 40GB data See full deal
at three.co.uk
(opens in new window)
Out of all the SIM only plans available this March on Three, we'd say their best value deal is their discounted 12‑month SIM below, which gets you 40GB data, plus unlimited minutes and texts for £14 £8 a month:
If you add up the £6 monthly discount, you’ll save £72 in total over the full 12 months on the 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 who's offering it for less here:
Their 80GB for £10 SIM is another good option
just
£10
a month
✔ Unlimited mins and 80GB data See full deal
at three.co.uk
(opens in new window)
To get a bigger chunk of data, our next best pick of Three SIM only plans is their discounted 12‑month £10 deal below, which gets you 80GB data and unlimited minutes and texts:
Even though it's in our pick of Three's best SIM only deals, you can actually beat it on price with other providers, including ones that also use the Three network. Here's where you can beat it on other networks:
Three's 120GB for £12 plan is a good option too
just
£12
a month
✔ Unlimited mins and 120GB data See full deal
at three.co.uk
(opens in new window)
If you need even more data, Three are also offering this discounted £18 £12 SIM, which includes 120GB data, unlimited minutes and texts on a 12‑month plan. It's another of their best deals:
It’s a discount of £6 a month against the full price, adding up to a £72 saving over the 12 months.
While this is a good enough deal to make it into the best of Three's SIMs, you can beat it for price (even if you definitely want a provider that uses the Three network). See lower-priced networks' deals here:
Their £18 for unlimited data plan is a decent deal for March
just
£18
a month
✔ Unlimited mins and unlimited data See full deal
at three.co.uk
(opens in new window)
For even more monthly data, you might like the discounted £28 £18 SIM only deal running on Three at the moment. It's a 12‑month plan, which comes with unlimited data, unlimited minutes and texts too:
That discount will save you £10 a month, which adds up to £120 over the course of the 12‑month deal.
It's a good enough deal to get into Three's best SIMs but you can actually get a lower price for a similar plan elsewhere, even if you definitely want it to use the Three network. Here are other networks you can beat it on:
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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