Last updated: 5 November 2026.
Next update: when Smarty or O2 Unlimited prices move, or when giffgaff’s 40GB £8 plan changes price.
By: Switch Editorial Team, Switch Squid Ltd
Prices: on 1 November 2026, giffgaff 40GB was £8 a month on an 18-month plan, and 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. On 9 October 2026, Smarty Unlimited was £20 a month and O2 Classic Unlimited £23 a month.
On 1 November 2026, giffgaff’s best-value data plan was 40GB for £8 a month on an 18-month plan running on O2’s network, with 25GB for £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 than 40GB, our giffgaff alternatives guide compares bigger plans. If you need true Unlimited, Smarty Unlimited costs £20 a month on a 30-day rolling plan (Three) and O2 listed Classic Unlimited at £23 a month for 24 months as a limited-time price on 1 November 2026. Confirm the price on the retailer’s page before you join.
The deal buttons on this page open the retailer’s own site. Browse our SIM only deals page for more options.
giffgaff 40GB — £8/mo · 18-month plan
- 40GB of 5G data, unlimited UK calls & texts, £8 a month as listed on giffgaff.com on 4 November 2026, for sign-ups before 4 December 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 needs an unlimited SIM?
giffgaff runs on O2’s network, so coverage comes first: if your home, commute or family’s house has weak O2 signal, the cheapest price won’t help. Heavy users who hotspot a laptop or stream on the move get the most from Unlimited; the live options are compared below.
If you mostly use Wi-Fi, price 25–80GB plans first. Paying for Unlimited you never use is the easiest way to overspend.
Price table (prices as listed on 9 October 2026)
Product | Data | Listed £/mo | Term | Network | Status |
|---|---|---|---|---|---|
Smarty Unlimited | Unlimited | £20 | 30-day | Three | On smarty.co.uk |
O2 Classic Unlimited | Unlimited | £23 | 24 months | O2 | Limited-time price listed on o2.co.uk on 1 November 2026 |
giffgaff 40GB (18-month) | 40GB | £8 | 18 months | O2 (giffgaff) | Sign up before 4 December 2026 |
Need true Unlimited? Smarty Unlimited is £20 a month, 30-day rolling, on smarty.co.uk. O2 Classic Unlimited was £23 a month for 24 months, a limited-time price O2 listed on 1 November 2026. The Smarty Unlimited button below shows £17 a month when you open Smarty from this page.
Smarty Unlimited — £17/mo · 1-month rolling
- Unlimited data with unlimited UK calls & texts on Three’s network, as listed on Smarty’s site on 4 November 2026
- £17 a month when you open Smarty from this page (£20 on Smarty’s own site), and you can leave any month
- Main limitation: 12GB EU roaming fair use. Check Three’s coverage at your postcode and confirm £17 on Smarty’s page before you pay
Prices as listed on 9 October 2026, and giffgaff’s on 1 November 2026. giffgaff’s 40GB plan at £8 a month (18 months) isn’t unlimited, but 40GB covers many phone users who are on Wi-Fi at home and work.
Unlimited alternatives vs giffgaff 40GB
If you still need true Unlimited, compare Smarty Unlimited £20 (Three, 30-day rolling) and O2 Classic Unlimited £23 (24 months, a limited-time price O2 listed on 1 November 2026). If 40GB is enough and O2 coverage suits you, giffgaff’s 40GB plan at £8 a month (18 months) costs less.
giffgaff’s community model (members, payback and forum help) is a nice extra, not a coverage guarantee. Fair-use and traffic-management terms still apply to any “Unlimited” plan, so read the plan terms at checkout.
giffgaff plans you can join
On 1 November 2026, giffgaff 40GB was £8 a month on an 18-month plan, and 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. Rolling monthly plans are also available. See giffgaff.com for the current list before you join.
Switching with a PAC or STAC
Text PAC to 65075 to keep your number, or STAC to 75075 if you are leaving without the number. Give the code to your new provider during / after activation as their flow requires. Ports usually complete in one working day once the gaining provider submits. Keep the old SIM until the number lands so banking OTPs survive the switch.
Roaming, 5G, eSIM and price rises
giffgaff offers 5G where the O2 mast and your handset allow, and eSIM on many modern phones. EU roaming allowances and fair-use limits can change, so read the current roaming page before a long trip and check the plan terms for the exact plan you buy.
Smarty 100GB — £10/mo · 1-month rolling
- 100GB of 5G and 4G data with unlimited UK calls & texts on Three’s network, as listed on Smarty’s site on 4 November 2026
- £10 a month when you open Smarty from this page (£12 at Smarty’s standard price), no credit check and no annual price rises
- Main limitation: Three’s network, not O2. Check coverage at your postcode first, then confirm £10 on Smarty’s page
FAQ
What are the best giffgaff Unlimited SIM only alternatives?
On 1 November 2026, giffgaff’s strongest-value plan was 40GB for £8 a month on an 18-month plan, with 25GB for £10 a month on the same term. For true Unlimited, Smarty Unlimited cost £20 a month (30-day rolling) and O2 Classic Unlimited £23 a month for 24 months, a limited-time price O2 listed on 1 November 2026. Check O2’s page for the price on the day you order.
Does giffgaff use O2’s network?
Yes. Coverage and 5G follow O2’s mast map. Run Ofcom’s checker for your postcodes before you port.
Is Unlimited truly uncapped?
“Unlimited” plans still come with fair-use and traffic-management rules. Read the plan terms before you rely on one for heavy tethering.
Which plan should I pick if I want lots of data on O2?
giffgaff 40GB at £8 a month (18 months) is the cheaper choice if 40GB is enough. O2 Classic Unlimited suits people who need true Unlimited on the same network. O2 listed it at £23 a month for 24 months as a limited-time price on 1 November 2026, so check O2’s page for the price on the day you order.
Can I keep my number?
Yes. Text PAC to 65075 to get your code, then give it to your new provider when you order. Your number usually moves within one working day.
Can I get giffgaff on a rolling monthly plan?
Yes. giffgaff sells rolling monthly plans alongside its 18-month plans. The 18-month plans usually cost less a month, so compare the monthly price and the term against how long you expect to keep the SIM.
What if the retailer shows a different price tomorrow?
Trust the basket on the day you buy. Prices in this guide were listed between 9 October and 1 November 2026, and retailers can change them at any time.
Is there a handset deal in this guide?
No. The deal buttons in this guide are SIM-only, so see our handset guides if you need a phone as well. SwitchSquid may earn a commission when you buy through the deal buttons, and it doesn’t change the price you pay.
