Last updated: Sunday 1 November 2026
By: Switch Editorial Team, Switch Squid Ltd
Our picks, checked on 1 November 2026: if you came here for a £6 SIM, our £6 pick is Smarty 18GB for £6 a month with our deal button, on a 1-month rolling plan. If you would rather be with giffgaff, its 40GB plan was £8 a month on an 18-month plan (£144 over the full term), and its 25GB plan £10 a month, as listed on 1 November 2026; giffgaff says the 40GB for £8 plan is for sign-ups before 4 December 2026. giffgaff’s own site lists its current goodybags — check it before you choose.
We may earn a commission if you buy using the deal buttons on this page. That does not change the price you pay. Confirm plan name, data, monthly price and term in the retailer basket before you pay.
Smarty 18GB — £6/mo with our deal button · 1-month rolling
- 18GB of 5G data, unlimited UK calls & texts, as listed on 1 November 2026
- 1-month rolling plan — no long contract
- Runs on Three’s network — confirm 18GB and £6 on SMARTY’s page before you pay
Our £6 pick (checked 27 October 2026)
Fact | Detail |
|---|---|
Plan | Smarty 18GB SIM only, with our deal button |
UK data | 18GB of 5G data |
Monthly price | £6 |
Calls and texts | Unlimited UK |
Term | 1-month rolling |
Network | Three (Smarty) |
Where to confirm | The SMARTY plan page our deal button opens |
Checked: 27 October 2026, on the SMARTY plan page our deal button opens, which shows 18GB for £6. Prices can change — re-check the retailer page on the day you buy. Compare other SIMs on our SIM-only deals pages.
If you want to stay on giffgaff
giffgaff runs on O2’s network. Its 40GB plan was £8 a month on an 18-month plan with unlimited UK calls and texts as listed on 1 November 2026, £144 over the full term — more than twice the data of Smarty 18GB for £2 more a month, in exchange for an 18-month commitment. Its 25GB plan was £10 a month on the same term. giffgaff says the 40GB for £8 plan is for sign-ups before 4 December 2026. If you need more data, our giffgaff alternatives guide compares bigger plans. Check giffgaff.com for its current goodybags and EU roaming allowance before you pay.
giffgaff 40GB — £8/mo · 18-month plan
- 40GB of 5G data, unlimited UK calls & texts, £144 over the full term, checked on 1 November 2026
- 18-month plan on O2’s network (giffgaff)
- giffgaff says the 40GB for £8 plan is for sign-ups before 4 December 2026. Confirm the £8 price and plan terms on giffgaff.com before you pay
Who each pick suits
Smarty 18GB £6 with our deal button (1-month rolling): light to moderate UK data users who want a low monthly price with no long contract, where Three coverage is good at home and work. 18GB covers maps, messaging, social media and some video — check your last few months’ usage in your phone settings or provider app before you switch.
giffgaff 40GB £8 (18 months): people who want more data on O2 coverage and are happy to commit for 18 months.
Consider alternatives if: you need truly unlimited data or heavy hotspotting — compare giffgaff Unlimited alternatives or a Three-based rolling plan such as Smarty.
Important conditions
Price checks: monthly prices can change. Confirm the £6 (Smarty) or £8 (giffgaff) price, data and term in the basket before you pay.
Rolling vs 18 months: Smarty 18GB is a 1-month rolling plan. giffgaff 40GB is an 18-month plan — leaving early can mean exit charges, so check coverage first.
Roaming: EU roaming allowances differ by provider and plan. Read each retailer’s roaming footnote before you travel.
Eligibility: some prices apply to new customers only — check the eligibility wording at checkout.
How they compare (small table)
Plan | Data | Monthly | Term | Network |
|---|---|---|---|---|
giffgaff 40GB | 40GB | £8 | 18 months | O2 |
Smarty 18GB (with our deal button) | 18GB | £6 | 1-month rolling | Three |
Smarty 40GB (with our deal button) | 40GB | £7 | 1-month rolling | Three |
Prices checked 27 October 2026 — re-check the retailer pages before you buy. Coverage, roaming and fair-use rules differ by network.
Illustrative SIM cost examples
These are static examples only. They assume a £6 monthly price and your current airtime price both stay unchanged, with no exit, setup or switching fees, and comparable service needs. They are not a guarantee that £6 lasts for twelve months.
Current SIM airtime | Illustrative monthly difference vs £6 | Illustrative 12-month difference |
|---|---|---|
£10 | £4 | £48 |
£15 | £9 | £108 |
£20 | £14 | £168 |
If your current bill includes handset repayments, compare airtime only — switching SIM may not remove the handset obligation. At £6 for 18GB, the included allowance works out at about £0.33 per GB (giffgaff 40GB at £8 is £0.20 per GB) as an allowance comparison, not an out-of-bundle rate. For a £5 existing SIM, the new plan would cost £12 more over 12 months under the same assumptions.
How to switch (PAC or STAC)
Check coverage for the postcodes you actually use (Ofcom’s mobile coverage checker is a sensible start) — Three for Smarty, O2 for giffgaff.
Open the plan via the button on this page and confirm data, monthly price and term in the basket.
Choose physical SIM or eSIM as supported for your handset.
Activate the new SIM.
To keep your number, text PAC to 65075 and follow the new provider’s port steps. To leave without the number, text STAC to 75075. Ports usually complete in one working day once submitted — keep the old SIM until the number lands so banking OTPs survive the switch.
Which should you take?
Take Smarty 18GB £6 with our deal button if 18GB fits your usage, Three coverage works for you, and you want a 1-month rolling plan.
Take giffgaff 40GB £8 if you want to stay on O2 with more data and are happy with 18 months.
Want more data on a rolling plan? Smarty 40GB was £7 a month with our deal button as listed on 27 October 2026, on a 1-month plan; SMARTY’s own site showed 32GB for £8. Need Unlimited? Browse our SIM-only deals pages.
Smarty 40GB — £7/mo with our deal button · 1-month rolling
- 40GB of 5G data, unlimited UK calls & texts, as listed on 1 November 2026
- 1-month rolling plan on Three’s network
- Confirm 40GB and £7 on SMARTY’s page before you pay
Affiliate disclosure: We may earn a commission if you buy with our deal buttons — that does not change the price you pay. Confirm plan name, data allowance, term and price on the retailer page before you pay.
FAQ
What is the best £6 SIM only deal?
On 1 November 2026, our £6 pick was Smarty 18GB for £6 a month with our deal button, on a 1-month rolling plan. If you need more data, giffgaff 40GB was £8 a month for 18 months (its 25GB plan was £10 a month), and giffgaff says the 40GB for £8 plan is for sign-ups before 4 December 2026. giffgaff.com lists its current goodybags if you want to compare them. We may earn a commission if you buy using the deal buttons on this page.
Is Smarty 18GB £6 a rolling plan or a fixed contract?
It is a 1-month rolling plan, so you are not locked into a long contract. Always confirm the term shown on SMARTY’s plan page before you pay.
Which networks do these plans use?
Smarty runs on Three’s network. giffgaff runs on O2’s network. Pick the one with the better signal where you live and work.
Can I keep my current number?
Yes. Text PAC to 65075, then complete the new provider’s port steps. Keep your old SIM active until the number has finished moving.
How much roaming is included?
EU roaming allowances vary by provider and plan. Confirm the destination list and any fair-use notes on the retailer’s plan details before you travel.
Can I choose an eSIM?
Both Smarty and giffgaff offer eSIM on many modern phones alongside a physical SIM. Choose the format your handset supports during checkout. If eSIM is not offered for your device, take the physical SIM instead.
Is it worthwhile if my current bill includes a phone?
Only compare the airtime portion. Switching to a SIM-only plan will not usually cancel handset repayments on your old contract. If you still owe on a phone, keep paying that finance and treat a £6 SIM as a possible airtime replacement — check both bills before you port.
