SIM only under £10: Smarty 40GB for £7 (October 2026)

Last updated: 27 October 2026
By: Switch Editorial Team, Switch Squid Ltd

Smarty update, when we checked on 27 October 2026: SMARTY’s own site showed 32GB for £8 a month on a 1-month plan, and our link opens 40GB for £7 a month on a 1-month plan. See our Smarty £8 plan guide.

Mozillion Pay Monthly Plus: you pay about half of a 24-month plan upfront, then the rest over 23 monthly payments. Every plan has unlimited UK calls and texts, uncapped 5G and EU roaming in 41 countries, and Mozillion says no credit check is needed. Prices on mozillion.com when we checked on 27 October 2026: 10GB £62.50 then £2.50 a month (£120 in total), 30GB £68.75 then £2.75 (£132), 100GB £81.25 then £3.25 (£156) and 310GB £100 then £4 (£192). All four sizes average under £10 a month, but the first payment is much bigger than a normal monthly bill.

When we checked on 27 October 2026, the best SIM only deals under £10 in the UK were mid-data plans: Smarty’s 40GB at £7 a month through our link on a 1-month plan (£84 over 12 months), iD Mobile’s 15GB at £6 a month on a 1-month plan, and giffgaff’s 40GB at £8 a month on an 18-month plan. This guide ranks everyday under-£10 SIMs for October, not another Unlimited beauty contest. We may earn a commission if you buy through our links.

For more SIM only deals across networks, see our best SIM only deals for October 2026.

Sources: Smarty, iD Mobile and Lyca Mobile plan pages and Mozillion’s plan pages, checked on 27 October 2026; giffgaff’s announcement of its £8 40GB offer (23 October 2026), checked on 27 October 2026.

Offer facts (checked 27 October 2026)

Smarty runs on Three; giffgaff runs on O2. Coverage differs by postcode — run each retailer’s checker for home, commute and workplace before you commit.

What “under £10” should mean in October

Under £10 is a monthly price ceiling, not a promise of Unlimited data. Most shoppers who type that phrase need maps, social video and hotspotting in moderation — roughly 20–40GB — not a blank data cheque. Paying £20 or more for Unlimited “just in case” is fine when you actually burn past 60GB; it is expensive habit when your Settings screen shows 18GB.

Illustrative 12-month cost (prices when we checked on 27 October 2026, not quotes):

• Lyca Mobile 30GB £5 + 11 × £10 = £115 (30-day plan, renew each month)

• Smarty 40GB £7 × 12 = £84 (through our link)

• iD Mobile 15GB £6 × 12 = £72 (1-month plan, Three network)

• giffgaff 40GB £8 × 12 = £96 during the 18-month term (£144 over 18 months)

• Smarty Unlimited £20 × 12 = £240 — outside this guide’s ceiling

When Smarty 40GB £7 wins

Choose Smarty when Three coverage is solid, you want an easy exit, and 40GB matches real usage. At £7 a month through our link it undercuts many 18-month mid-data contracts on monthly price while keeping the cancellation door open for students, renters and anyone testing a new city signal.

When giffgaff under £10 fits better

iD Mobile 15GB £6: light users with good Three signal who want a 1-month plan.
giffgaff 40GB £8 / 18 months: stable O2 coverage and you will keep the line for the term — £8 stays under the £10 ceiling with 40GB on O2.
Skip Unlimited for this brief unless Settings already proves you need it — then read our rolling-vs-18-month and giffgaff-vs-Smarty Unlimited guides instead.

Fit summary

Good for Smarty 40GB £7 through our link: Three coverage, mid-data habits, want month-to-month flexibility.
Good for iD Mobile 15GB £6: lighter data, Three coverage, want the lowest ongoing monthly cost on a 1-month plan.
Good for giffgaff 40GB £8: O2 homes willing to commit 18 months.
Not for: heavy hotspotters who routinely pass 60GB — budget for Unlimited instead.

Important conditions

• Prices can change, so confirm the retailer page on the day you order.

• 18-month plans carry early-termination charges.

• Fair-use, roaming caps and 5G availability sit in each retailer’s terms.

• eSIM vs physical SIM: order early if you are travelling or changing handset the same week.

• Keep a PAC text (65075) ready if you are porting your number.

Switching steps

1) Check monthly data use in Settings for the last three months.
2) Run Three (Smarty) and O2 (giffgaff) coverage for home and commute.
3) If 40GB and Three look right, order Smarty 40GB at £7 through our Check availability button.
4) Activate, confirm data with Wi-Fi off, then port your number if needed.
5) Diary any price change dates so a step-up does not surprise you.

Final decision card

Three coverage + mid-data → Smarty 40GB £7 through our link.
Light data + lowest price → iD Mobile 15GB £6 (1-month plan).
O2 coverage + stable 40GB need + can commit → giffgaff 40GB £8 / 18 months.
Heavy data → leave the under-£10 aisle.

Worked examples

Renter on a 12-month tenancy: Smarty 40GB at £7 through our link keeps an exit door if you move to a Three-weak postcode later.

Parent buying a teen line: a 15GB £6 plan such as iD Mobile’s often covers school Wi-Fi habits; upsize only if gaming hotspotting appears in the bill.

Commuter who maps offline areas: 40GB is the safer under-£10 bucket; Unlimited only if tethered laptop days are routine.

Related SwitchSquid SIM guides

For Unlimited term maths see rolling vs 18-month October. For brand Unlimited detail see giffgaff vs Smarty Unlimited. For household multi-line sizing see family SIM sharing October. This guide sticks to plans under £10 a month.

Roaming and EU trips on a £6–£8 plan

Under-£10 UK plans are priced for domestic use. Roaming allowances are smaller than marketing memory suggests. For a two-week holiday, a temporary travel eSIM can be cheaper than upsizing to Unlimited at home “just in case”. Read the retailer’s roaming page before you promise free maps abroad.

5G, fair use and hotspotting

“5G data” on the plan label does not mean unlimited hotspotting. Tethering a laptop on a 40GB plan empties the bucket in days. If work-from-train is your normal week, budget data honestly or pick Unlimited on a separate guide. Fair-use clauses still apply on some Unlimited products too — read the plan terms rather than assuming a blank cheque.

How to size 20GB versus 40GB without guessing

Open your phone’s data usage screen and look at the last full billing month, not a quiet week on holiday Wi-Fi. Add a buffer of about 20% if you expect a new commute or a child starting school apps. If three recent months average 10–12GB, iD Mobile’s 15GB at £6 is usually enough. If you sit at 28–35GB, Smarty 40GB at £7 through our link (1-month plan) or giffgaff’s 40GB at £8 (18 months, O2) both stay under £10.

Hotspotting is the silent budget killer. A single evening of tethering a laptop for updates can burn 5–10GB. If that is weekly behaviour, stop pretending mid-data will hold and budget for Unlimited on a different guide. If it is rare, stay under £10 and use café or home Wi-Fi for big downloads.

Handset compatibility still matters. A network-locked phone will not thank you for a perfect £8 plan. Unlock first, or buy a handset that is already unlocked. eSIM-capable phones can activate faster; physical SIM buyers should order a few days early around bank holidays.

Credit checks, top-ups and bill-payer hygiene

Month-to-month value SIMs are often lighter on credit checks than 24-month handset contracts, but checkout prompts vary. Read what the retailer asks for. Top-up brands need a funding method you will actually remember — failed top-ups are how people accidentally roam onto expensive casual data.

Parents paying for a teen line should decide whether the account sits under the teen’s login or a parent email. Renewal texts and PAC codes go to whoever controls the account. Diary the first renewal so a promo step-up does not become a surprise Direct Debit.

FAQ

What is the cheapest under £10 SIM in October 2026?

When we checked on 27 October 2026, Lyca Mobile’s 30GB was £5 for the first 30 days, then £10. For a lower ongoing price, iD Mobile’s 15GB and SMARTY’s 5GB were both £6 a month on 1-month plans. For more data under £10, Smarty 40GB was £7 a month through our link on a 1-month plan, and giffgaff’s 40GB was £8 a month on an 18-month plan. Confirm the price on the retailer’s page before you buy.

How much are Smarty’s mid-data plans?

When we checked on 27 October 2026, SMARTY’s own site showed 32GB for £8 a month on a 1-month plan, and 40GB was £7 a month through our link, both with unlimited UK calls and texts. Prices can change, so confirm at checkout.

Is giffgaff 40GB under £10?

Yes. When we checked on 27 October 2026, giffgaff’s £8 18-month plan came with 40GB a month; giffgaff says that allowance is for plans activated by 4 December 2026. Early-exit charges apply if you leave before 18 months.

Which network is Smarty on?

Smarty uses the Three network. giffgaff uses O2.

Can I keep my number on a cheap SIM?

Yes. Text PAC to 65075 from your current provider and port after the new SIM is active.

Should I buy Unlimited instead?

Only if you regularly need more than about 40–60GB. Otherwise an under-£10 mid-data plan is usually enough.

Do SIM prices change?

Yes. Introductory prices and plan line-ups can change at short notice. Order while the retailer page still shows the price you expect.

Do you earn commission?

Yes. SwitchSquid may earn a commission at no extra cost to you when you buy through the deal buttons on this page.