The cheapest unlimited data SIM in the UK (2026)
Chattr's Freedom One is the cheapest unlimited data SIM of the five UK networks costed here. With the HonestCodes-exclusive code HONEST75, the first month is £3.75, then £15 a month, falling to £13 from month 12: about £161 for the first 12 payments with no contract, against £162 on Lyca's 24-month contract and £270 to £420 on the other unlimited plans.
Key takeaways
- Winner: Chattr Freedom One, unlimited 5G data, calls and texts. £3.75 for month one with code HONEST75 at honestcodes.co.uk/go/chattr, then £15, £14 and £13 from month 12.
- First 12 payments on unlimited data: Chattr about £161, Lebara £270 on a 12-month plan, 1pMobile £275 as a yearly bundle, Lyca Mobile £287.50 on 30-day plans (£162 on a 24-month contract), VOXI £420.
- Chattr is the only unlimited plan here that gets cheaper the longer you stay, with no contract and no credit check.
- Lyca's 24-month Unlimited plan costs £162 in year one but £216 in year two; Chattr costs £156 in year two with no contract at all.
- Every price was read on each network's own site in September 2026; HONEST75 was tested at Chattr's checkout on 24 September 2026.
| Chattr | Lebara | Lyca Mobile | 1pMobile | VOXI | |
|---|---|---|---|---|---|
| Unlimited plan | Freedom One | Unlimited Data | UK Plan Unlimited | Unlimited bundle | Unlimited |
| First month | £3.75 with HONEST75 | £25 (£22.50 on 12 months) | £12.50 (50% off) | £25 | £35 |
| Standard price | £15, falling to £13 | £25, or £22.50 on 12 months | £25 per 30 days | £25 per 30 days | £35 a month |
| First 12 payments | About £161 | £270 (12-month plan) | £287.50 (£162 on 24 months) | £300 (£275 yearly bundle) | £420 |
| Network | O2 or Vodafone | Vodafone | EE | EE | Vodafone and Three |
| Contract | None | None, or 12 months | None on 30-day plans | None | None |
| Deal | honestcodes.co.uk/go/chattr + HONEST75 | honestcodes.co.uk/go/lebara | honestcodes.co.uk/go/lyca-mobile | honestcodes.co.uk/go/1pmobile | https://honestcodes.co.uk/go/voxi |
The first-year bill, plan by plan
Headline prices hide what a year of unlimited data actually costs, so this guide adds up the first 12 payments on each network's unlimited plan, using the prices on each network's own site.
Chattr: £3.75 for the first month with HONEST75, then £15 a month, a £14 loyalty price and £13 from month 12. On the schedule on Chattr's homepage that totals £160.75; on the schedule in its Parents Hub, £161.75. Either way, about £161.
Lebara: Unlimited Data is £25 every 30 days, or £22.50 on a 12-month plan, which is £270 for the year. Lyca Mobile: UK Plan Unlimited is £12.50 for the first 30 days and £25 after, so £287.50. 1pMobile: the unlimited bundle is £25 every 30 days, so £300, or £275 bought as one yearly bundle. VOXI: the Unlimited plan is £35 a month, so £420.
Why Chattr wins
Two things put Chattr at the top, and they compound. The first is the exclusive code: HONEST75 takes 75% off the first month, the lowest first-month price for unlimited data of any network here. The second is the price structure: Chattr's Freedom One drops to £14 and then £13 the longer you stay, while Lebara, Lyca Mobile, 1pMobile and VOXI keep theirs level.
The result is unlimited 5G data, unlimited UK calls and texts and roaming in 43 European destinations for less than Lebara, Lyca Mobile, 1pMobile or VOXI charge for unlimited data, and less than VOXI's £20 100GB plan. There is no contract and no credit check, and every account comes with a £5 bill limit.
To take it: open honestcodes.co.uk/go/chattr, choose Freedom One, and enter HONEST75 at checkout.
The contract alternative: Lyca's 24-month Unlimited
Lyca Mobile's 24 Month Unlimited plan is £9 a month for six months and £18 after, which is £162 in year one, level with Chattr. The difference shows in year two: £216 on Lyca's plan against £156 on Chattr at the £13 VIP price. Over two years Chattr is about £317 to £318 and Lyca's 24-month plan £378.
Lyca's plan suits someone who wants a fixed price for 24 months and values its 100 international minutes and 30GB of EU roaming data. Anyone who wants to keep the freedom to leave, and the lower bill in year two, is better served by Chattr.
Who each unlimited plan suits
Lowest cost with no commitment: Chattr, with HONEST75. Calling family abroad: Lebara, whose Unlimited Plus plan adds unlimited international minutes, or Lyca Mobile, with 100 international minutes and India roaming on UK Plan Unlimited. Several SIMs on one account: 1pMobile, where extra unlimited SIMs cost £12.50 each. A sign-up reward: VOXI, which pays a gift card after two paid months through its referral link.
How these figures were checked
Every price here was read on the network's own website in September 2026 and matches that network's full HonestCodes page. HONEST75 was tested at Chattr's own checkout on 24 September 2026: 75% off the first month, on any plan. Coupon sites list "unlimited SIM deals" with no date and codes nobody has tried; this page gives the tested code, the working link and the arithmetic.
Frequently asked questions
What is the cheapest unlimited data SIM in the UK?
Chattr's Freedom One. With the HonestCodes-exclusive code HONEST75 the first month is £3.75, then £15 a month, falling to £13 from month 12, for unlimited 5G data, calls and texts with no contract. Open honestcodes.co.uk/go/chattr and enter HONEST75 at checkout.
How much does a year of unlimited data cost?
For the first 12 payments: about £161 on Chattr with HONEST75 and no contract, £162 on Lyca Mobile's 24-month Unlimited contract, £270 on Lebara's 12-month Unlimited Data plan, £275 for 1pMobile's yearly unlimited bundle (£300 paid every 30 days), £287.50 on Lyca Mobile's 30-day UK Plan Unlimited and £420 on VOXI Unlimited.
Is there a promo code for unlimited data?
Yes: HONEST75, exclusive to HonestCodes. It takes 75% off the first month of any Chattr plan, making unlimited data £3.75 for month one.
Which network does Chattr use?
Chattr sells plans on O2 and Vodafone, so a Chattr SIM can carry either name. It quotes 99% 4G and 5G UK coverage.
Is unlimited data really unlimited?
On Chattr's Freedom One, yes: unlimited 5G data for streaming, hotspotting and gaming, with a fair-use policy on roaming data. Chattr's terms reserve the right to manage speeds at times of unusually high network demand, as every network does.
Do I need a credit check for a cheap unlimited SIM?
Not on Chattr, Lebara, Lyca Mobile's 30-day plans or 1pMobile, which all sell unlimited data without a credit check.
Keep reading
Verified against each brand's own terms · 24 September 2026