£14.08
a month for an unlimited 5G SIM at Affordable Mobiles, after automatic cashback
Cheapest unlimited SIM: how much you actually save at Affordable Mobiles
The numbers in brief
~55%
less than the same unlimited plan bought direct from Three — about £203 a year
~half
of the £26.60 average cheapest-unlimited price across five leading UK networks
The short version
Prices compiled on 4 June 2026: an unlimited 5G SIM at Affordable Mobiles works out at £14.08 a month once the automatic cashback is applied. Buying the same unlimited plan direct from Three costs £31 a month, so you pay about 55% less through Affordable Mobiles, which is roughly £203 over a year. Look wider, and the cheapest unlimited SIM across five leading UK networks averages £26.60 a month, which puts Affordable Mobiles at about half the going rate for unlimited data.
Those are big claims, so the rest of this page shows the working: where each number comes from and what to double-check before you buy. For the live Affordable Mobiles discount codes and deals, head to our main page; here we focus on the maths.
How we worked this out
I see a lot of "save up to" headlines with no figures behind them, so we wanted to do the opposite here. Every number on this page is either Affordable Mobiles' own published price or simple arithmetic on prices we recorded ourselves, with the source and the date noted. Nothing is estimated. Where two plans were not a perfect match, we have said so rather than smoothing over it.
- Prices captured: 4 June 2026.
- What we compared: unlimited-data 5G SIM-only plans, the closest like-for-like we could find from each provider.
- The Affordable Mobiles price: £14.08 a month for a Three Unlimited 5G SIM, on a 12-month plan with nothing to pay upfront. That figure already has the automatic cashback applied.
- The rule we stuck to: no source, no claim. If we could not stand a figure up, it is not on this page.
A quick word on the cashback, because it matters for the comparison. Affordable Mobiles applies its Guaranteed Cashback automatically, so the £14.08 is what you actually pay each month, not a figure you have to claim back later. Before cashback the same SIM is £17 a month, which is still below most of the prices we found elsewhere.
Same network, two very different prices
The cleanest comparison is the most direct one: the same network, the same type of plan, bought two different ways.
| Where you buy | Plan | Monthly | Term |
|---|---|---|---|
| Affordable Mobiles | Three Unlimited 5G (after cashback) | £14.08 | 12 months, £0 upfront |
| Three, direct | Unlimited (entry "Lite" tier) | £31.00 | 12 months, £0 upfront |
Same network, same unlimited data, same 12-month term, both with nothing to pay upfront. You pay £16.92 less a month, which adds up to £203.04 over the year, or about 55% less than going direct.
One honest note in Affordable Mobiles' favour: £31 is Three's cheapest unlimited tier, the speed-capped "Lite" plan. Three's faster tiers cost more, so if anything this comparison understates the gap. (Worth knowing for later: Three's own price is set to rise to £33.30 from 1 April 2027.)
Top Tip: when you compare SIM deals, always line up the same network and the same contract length. It is the only way to see what you are really saving rather than what a headline wants you to think you are saving.
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How it compares to the wider market
Sticking to one network is the fairest test, but it is also fair to ask how Affordable Mobiles' £14.08 stacks up against the market as a whole. So we took the cheapest unlimited SIM from five leading UK providers and worked out the average.
| Provider | Cheapest unlimited SIM | Term | Worth knowing |
|---|---|---|---|
| Three | £31.00 | 12 months | "Lite" tier, speed-capped |
| EE | £27.00 | see note | "No Frills", capped at 10Mbps; rises later in the plan |
| Vodafone | £26.00 | 24 months | base Unlimited, speed-managed |
| Tesco Mobile | £25.00 | 24 months | price frozen for the term; £20 with a Clubcard Price |
| O2 | £23.99 | 24 months | "Unlimited Plus" |
Average those five and you get £26.60 a month. At £14.08, Affordable Mobiles is about 47% below that average, which is roughly half the price of a typical unlimited SIM.
I want to be straight about the limits of this one. These are each provider's cheapest unlimited tier, but they are not identical: some run 12 months and some 24, a few cap your speed, and several rise in price part-way through. So treat this as "the cheapest unlimited option from each provider", not a perfectly matched basket. It is useful for context; the same-network comparison above is the precise one.
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Is a contract cheaper than buying the phone outright?
While we had the numbers out, we ran one more sum that almost nobody shows you. If you are buying a new phone, is it actually cheaper to take it on a contract, or to buy it SIM-free and add one of these cheap SIMs yourself? We compared the contract's full two-year cost against the manufacturer's outright price plus a £14.08 SIM for 24 months.
| Phone | On contract (24 months) | Buy outright + add a SIM | Difference |
|---|---|---|---|
| iPhone 17, 256GB | £1,023 | £799 + £337.92 = £1,136.92 | contract about £114 cheaper |
| iPhone 17 Pro, 256GB | £1,419 | £1,199 + £337.92 = £1,536.92 | contract about £118 cheaper |
So on these two handsets, taking the contract works out a little over £100 cheaper across two years than buying the phone outright and adding a SIM. The maths is exact, but two honest caveats: contract monthly prices usually rise once a year, which narrows the gap over time, so read this as "at today's rates". And these are list prices on the day we checked, so confirm the live deal before you decide.
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Compare across networks and resellers
Affordable Mobiles isn't the only place worth checking. If you're comparing resellers, our Mobiles.co.uk and Buymobiles pages bundle handsets and SIMs the same way. If you would rather go direct to a network, take a look at iD Mobile and Tesco Mobile. It is always worth lining up two or three before you commit.
The savings, in one place
- Unlimited 5G SIM: £14.08 a month after automatic cashback, down from £17 before it. About 55% less than the same plan direct from Three, or roughly £203 a year.
- A 100GB 5G SIM: £11 a month after cashback, down from £15, saving £48 over the year.
- Versus the market: roughly half the £26.60 average cheapest-unlimited price across five leading providers.
- Buying a new phone: on the handsets we checked, a contract came out around £114 to £118 cheaper over two years than buying outright and adding a SIM.
How to get these savings at Affordable Mobiles
You do not need a code for any of this, which is the part people find surprising.
- Head to Affordable Mobiles and choose SIM-only if you already have a phone you are happy with.
- Filter to unlimited data and compare the after-cashback monthly price, not the upfront, because the cashback is where the saving sits.
- Check the plan length suits you; the cheapest unlimited deal here runs over 12 months with nothing to pay upfront.
- Place your order. The Guaranteed Cashback is automatic and paid to your bank by BACS 90 days after your order ships, so there is nothing to claim.
For the full picture on cashback, trade-in and delivery, see our main Affordable Mobiles discount codes and deals page.
Frequently asked questions
What is the cheapest unlimited SIM at Affordable Mobiles?
+A Three Unlimited 5G SIM at £14.08 a month after the automatic cashback, on a 12-month plan with nothing upfront. Before cashback it is £17 a month (prices as of 4 June 2026).
How much cheaper is it than buying direct from Three?
+About 55% cheaper. The same unlimited Three plan, bought direct from Three on the same 12-month term, was £31 a month when we checked. Through Affordable Mobiles it is £14.08, a saving of around £203 over the year.
Is £14.08 really half the market price for unlimited data?
+Roughly, yes. The cheapest unlimited SIM from five leading UK providers averaged £26.60 a month on 4 June 2026, so £14.08 is about 47% below that. Bear in mind those plans vary in length and speed, so it is a guide to the wider market rather than an exact like-for-like.
Do I need a discount code to get this price?
+No. The saving is built into the price through automatic cashback, so there is no code to enter and nothing to claim back later.
Will these prices still be live when I look?
+They might have moved. Mobile prices change often, so we have dated everything to 4 June 2026. Always check the live price on the deal before you order.