Last updated: Tuesday 8 September 2026 (Europe/London).
Next update: when Talkmobile changes the Flex 15GB £5.95 rate, when spusu reprints the 15 plan pound, when SMARTY’s own site finally prints a clean labelled 15GB price I can defend, or when the live SIM hub shows a cheaper same-allowance 12-month total on a retailer page I can open.
By: Switch Editorial Team, Switch Squid Ltd
I am Switch. I compare SIMs for a living, and 15GB SIM only deals UK in September 2026 is the just-above-average rung comparison sites keep answering with a filter on a generic hub — or with a “15GB†grid that quietly mixes 12GB, 16GB and 20GB on the same page.
uSwitch has no dedicated 15GB guide URL. You land on the SIM-only compare table, tick a box, and hope the card still means 15GB by checkout. This page is one tier: exact labelled ~15GB, priced from retailer shops on Tuesday 8 September 2026.
Our SIM only hub is every network and every allowance, ranked by total monthly cost. This URL stays on 15GB.
The cash lead this morning is Talkmobile 15GB Flex at £5.95 rolling on talkmobile.co.uk/sim-only-deals (JSON-LD SKU flex-15gb-6) — twelve months £71.40, unlimited UK minutes and texts, Vodafone masts, 5G where available. One rung behind on EE masts is spusu 15 at £6.90 on spusu.co.uk/plans — twelve months £82.80.
Ofcom’s Communications Market Report 2026 puts average monthly data per mobile data user at 11.8GB in 2025 (CMR 2026 PDF). So 15GB sits just above average — not the light 5GB bucket, not the commute-streamer 30GB shop. If last month was under 6GB, start with 5GB. If it was 18GB-plus with a week still to go, use 20GB or 30GB.
I will not invent a 15GB SKU. I will not rank a uSwitch tile the retailer’s own site does not sell. Every pound in the ranking table below is dated to a retailer page I am standing behind on 8 September 2026.
Filter 15GB on the hub
Open the SIM only hub. Set data around 15GB, pick 30-day or 12-month, sort by total monthly cost. Commission does not move a row. If a 12GB or 20GB card is sitting on a “15GB†filter, you filtered wrong — or the live feed mixed a neighbour tier.
Need a new handset instead of airtime? That is a different bill: compare phone deals or phone deals hub.
Already sure you want a thinner or fatter cap? Neighbour guides are 5GB SIM only deals UK, 20GB, 30GB, 40GB, 50GB, 100GB, and cheapest unlimited. This URL stays on 15GB.
Switch the SIM, keep the phone — 15GB is about the airtime bill, not a new handset.
What I verified today
Two retailer-verified exact-labelled ~15GB plans. Dated Tuesday 8 September 2026. Near-tier cards (12GB, 10GB, 20GB, 30GB) live in the notes, not as fake 15GB rows. Comparison exclusives and unverified shop pounds live in “What I droppedâ€.
Talkmobile 15GB Flex, talkmobile.co.uk/sim-only-deals, fetched 8 September 2026: JSON-LD SKU flex-15gb-6, £5.95 a month, 30-day contract, 15GB data, unlimited UK minutes and texts. Vodafone masts. 5G where available. EU roam fair-use on shop copy — confirm the 5GB-style FUP at checkout before you treat a week in Spain like home data. Twelve-month total £71.40, average £5.95. This is the cash lead for unlimited UK calls at exact 15GB.
spusu 15, spusu.co.uk/plans (JSON-LD on the plans page), fetched 8 September 2026: £6.90 a month rolling. 15GB, unlimited minutes, unlimited texts. EE network. EU/Switzerland roam printed as 6GB / 500 minutes / 500 SMS on the plan schema. Twelve-month total £82.80, average £6.90. Eleven pounds forty more than Talkmobile for the year — and EE coverage if that is the mast that works at your postcode.
What I dropped
Comparison hubs and thin “15GB†round-ups still try to sell these as 15GB. Retailer shops do not match, or I could not verify the pound on the shop today.
SMARTY 15GB — a 15GB URL exists, but I could not cleanly extract an own-site monthly pound on 8 September 2026. Omitted. I will not invent a SMARTY figure.
Exact 10GB national shop ladder — thin today. spusu has no 10; Talkmobile’s Flex ladder starts at 15; SMARTY 10/12 redirects toward 16GB. Not ranked as 15GB.
Any uSwitch “15GB from £X†exclusive that does not match shop JSON-LD. Dropped per retailer-own-site rule.
iD 12GB / iD 20GB — real shop cards, wrong allowance. They sit in the neighbour notes below, not in the 15GB table.
If a tile is cheaper than Talkmobile’s shop £5.95 and the retailer’s own site does not print that exact 15GB SKU, the tile is not a deal. It is a trap for people who do not click through.
Ranked by what you actually pay
Four columns. Ongoing rate is what the bill is while the current rolling rate holds. Average is the 12-month total divided by 12. Every row below is retailer-verified labelled ~15GB on 8 September 2026.
Plan (dated 8 Sep 2026) | Term | Ongoing £ / month | 12-month average |
|---|---|---|---|
Talkmobile Flex 15GB (talkmobile.co.uk, unltd mins/texts, Vodafone, SKU flex-15gb-6) | 30-day | £5.95 flat | £5.95 (£71.40 total) |
spusu 15 (spusu.co.uk/plans, unltd mins/texts, EE, EU/CH 6GB roam) | Rolling | £6.90 flat | £6.90 (£82.80 total) |
£5.95 is the Talkmobile month. £71.40 is that year. £6.90 is the spusu month. £82.80 is that year.
Over twelve months Talkmobile is £71.40. spusu 15 is £82.80 — £11.40 more for EE masts and a printed 6GB EU/Switzerland roam line. That is the honest two-row ladder at exact 15GB this morning. Everything else that looks “about 15GB†is a neighbour with a different label.
£5.95 is the unlimited-calls year
If Vodafone coverage works at your postcodes and you want unlimited UK calls and texts on a rolling 15GB SIM, the cheapest retailer-verified year I can print today is Talkmobile Flex 15GB at £5.95 × 12 = £71.40 on talkmobile.co.uk. No 24-month lock on that Flex SKU.
If you want EE coverage, spusu 15 at £6.90 is £82.80 for the year on spusu.co.uk/plans — eleven pounds forty more than Talkmobile. That is the honest EE-mast lead at exact 15GB.
There is no third exact-15GB national shop row I can defend this morning. That is not me being lazy. The mid-light tier is thin: Talkmobile starts its Flex ladder at 15, spusu prints 15, and SMARTY’s own 15GB pound stayed unverified. I would rather publish two honest rows than pad the table with 12GB and 20GB dressed as 15.
15GB sits just above Ofcom’s average
Ofcom’s 2026 CMR figure is 11.8GB average per mobile data user in 2025. A 15GB SIM is a little above that average — enough headroom for maps, social apps, messaging and the odd commute stream without buying a 30GB “just in case†bill.
Illustrative only, labelled as such: at a rough 3GB per hour for HD streaming, 15GB is about five hours of video a month before everything else eats the rest. If Settings → Mobile Data (iPhone) or the Android data-usage screen showed 9–13GB last month with a week still to go, you are in the right shop. If it showed 3–5GB, you are overpaying for headroom — start on the 5GB guide. If it showed 18–25GB, look at 20GB or 30GB instead.
Ofcom’s average mobile data user sits at 11.8GB — 15GB is just above that line.
I am not going to pretend 15GB is “unlimited in disguiseâ€. Heavy hotspotting, a week of 4K, or holiday roaming under a tight fair-use cap will still bite. That is why the fatter September guides exist.
The neighbour traps (not fake 15GB rows)
This is where September shopping goes wrong. Same-ish cash. Wrong allowance. Or a lock you did not ask for.
Neighbour (not a 15GB row) | Cash note | Why it is not in the table |
|---|---|---|
iD Mobile 12GB 24 Months £6 | £72/year | Only 12GB, and a 24-month lock |
iD Mobile 20GB £6 (24m / 12m / 1m) | £72/year | 20GB — same pound as iD 12GB; more data than 15 |
Mozillion 10GB (24m £7.95 / 12m £8.50 / 1m £8.95) | £95.40 / £102 / £107.40 | 10GB, not 15; cash list only (ignore FREE rewards) |
Talkmobile Flex 30GB £6.95 | £83.40/year | Next Talkmobile rung — double the data for £1 more a month |
Read that carefully. iD’s 12GB at £6 and iD’s 20GB at £6 can print the same monthly pound. The trap is locking twenty-four months for 12GB when the same shop’s 20GB card is the same cash and more data — and neither of those is a labelled 15GB row, so they stay out of the ranking table. If you will stay a year on Three anyway, compare those iD cards on idmobile.co.uk before you force a 15GB label.
Talkmobile’s next Flex rung is 30GB at £6.95 — twelve months £83.40. That is only £12 more than the 15GB Flex year for double the allowance. If Settings already shows you kissing 14GB by week three, stop romanticising the 15GB URL and open the 30GB September guide.
Mozillion’s 10GB cash list sits above Talkmobile’s 15GB year even before you count the thinner allowance. I print it so you do not treat a “cheap 10GB†tile as a 15GB win.
You are buying a mast, not a logo
15GB on a dead mast is 0GB. The four UK networks still sit under the MVNO names.
If you want this mast | 15GB plan I named today | Parent | Check before you pay |
|---|---|---|---|
Vodafone | Talkmobile Flex 15GB £5.95 (cash lead) | Vodafone | Indoor signal at home and work; roam FUP at checkout |
EE | spusu 15 £6.90 | EE | EE coverage map; EU/CH 6GB roam line on plan schema |
Three | No exact labelled 15GB shop row today — iD 12GB / 20GB neighbours | Three | Do not invent a 15GB iD SKU; compare 12 vs 20 at £6 |
O2 | No retailer-verified exact 15GB on shop this morning | O2 | Reopen giffgaff / O2 yourself; do not trust a comparison ghost tile |
Coverage checkers lie less than marketing pages. Test the mast that already works on a friend’s phone in your kitchen before you port.
30-day vs locking a year at this tier
Talkmobile Flex 15GB and spusu 15 are short commitment. That is the point of mid-light shopping in September: you can leave after a month if the mast is wrong.
24-month locks only win when the monthly pound drops enough to beat rolling cash and you will actually stay. At exact 15GB this morning, the cash lead is already a 30-day Talkmobile SKU. The lock story that matters is next door: iD’s 12GB / 20GB at £6 on longer terms — different allowances, same-ish cash, not 15GB rows.
April rises still exist on many big-network SIMs. Read the checkout small print on Talkmobile and spusu, not a blog table from last spring.
Roaming, eSIM and PAC, without the brochure
Talkmobile / Vodafone-family roam rules sit on the checkout — confirm the fair-use data line before you buy a week abroad on a “cheap 15GB†assumption. spusu 15 lists 6GB EU/Switzerland roam data plus 500 minutes / 500 SMS on the plan schema. That is useful for a short trip. It is not a second full UK allowance.
eSIM: spusu leans into eSIM on the plan journey. Talkmobile Flex still ships as a physical SIM journey for many baskets. If your phone is eSIM-only, check the retailer basket before you celebrate the £5.95 lead. We have a separate explainer if you need the basics: what is an eSIM.
Keeping your number: Text to Switch (or the older PAC/STAC path where it still applies) moves the number. Start the port from the new retailer’s app or checkout after the SIM is active. Step-by-step: how to get a PAC code and Text to Switch explained.
How I ranked these (and what I refuse to do)
I open the retailer’s own SIM page. I take the monthly pound and the contract length printed there. I multiply by twelve. I sort by that 12-month cash. I do not sort by commission. I do not sort by “from†price on a comparison exclusive.
I refuse to:
count a 12GB or 20GB tile as 15GB because a filter said “15GB+â€
print a SMARTY pound I could not match on the shop today
hide a 24-month lock behind a soft “about £6†neighbour note
pretend cashback portals change the retailer sticker price
Affiliate links, when we use them, do not move a row in this table. If Talkmobile is cheaper on talkmobile.co.uk than a partner deep link, the shop price wins the ranking.
FAQ
What is the cheapest 15GB SIM only deal in the UK right now?
On retailer pages I opened on 8 September 2026, Talkmobile Flex 15GB at £5.95 a month (£71.40 over twelve months) is the cash lead for unlimited UK calls and texts. spusu 15 at £6.90 (£82.80) is the EE-network lead.
Is 15GB enough data?
For many people, yes — Ofcom’s 2025 average was about 11.8GB per mobile data user, so 15GB sits just above average. Check last month’s usage in Settings before you buy. Under ~6GB, look at 5GB. Over ~18GB, look at 20GB or 30GB.
Should I take Talkmobile 15GB or Talkmobile 30GB?
If you consistently sit under ~12GB, take 15GB at £5.95. If you regularly brush 14GB by month-end, Talkmobile’s 30GB Flex at £6.95 (£83.40/year) is only about £12 more for the year and doubles the allowance. Do not buy the thinner label out of habit.
Why is iD’s £6 card not in the table?
Because today’s iD cards at £6 are 12GB or 20GB, not labelled 15GB. Same cash can buy more data on the 20GB card — but that is a neighbour, not a fake 15GB row.
Why did you omit SMARTY 15?
Because I could not cleanly verify the own-site monthly pound on 8 September 2026. Comparison teasers that are not matched on the retailer shop do not get a row.
Do these prices rise every April?
Many big-network SIMs still use April rises. Talkmobile Flex and spusu rolling cards need the checkout rise clause read in full — not a blog table from last spring.
Can I keep my number?
Yes. Text to Switch (or the older PAC/STAC path where it still applies) moves the number. Start the port from the new retailer’s app or checkout after the SIM is active.
Can I get an eSIM?
Often yes on spusu; Talkmobile Flex is still physical-SIM for many baskets. Confirm in the retailer checkout before you pay if your phone is eSIM-only.
Where do I compare live SIMs across every allowance?
Use the SwitchSquid SIM only hub — filter around 15GB, sort by total monthly cost, then click through to the retailer before you pay.
Compare live 15GB SIMs
Retailer pages move. This ranking is dated 8 September 2026. Before you pay, open the shop URL in the table, confirm the pound, and check coverage at your postcodes.
Ready to filter the live grid? Compare SIM only deals on SwitchSquid — every network, sorted by what you actually pay, not by who shouted loudest on a comparison tile.
Switch Squid Ltd, company number 13332631, Leamington Spa. 01926 942125.
