Cheap SIM Only Deals UK 2026: How to Cut Your Mobile Bill

![Senior traveller researching cheap SIM only deals at a busy tour office in Ho Chi Minh City

What cheap SIM only deals actually include

Get your eSIM for Vietnam before you travel.

![Senior traveller researching cheap SIM only deals at a busy tour office in Ho Chi Minh City

A SIM only deal covers data, calls, and texts. No handset. You pay for connectivity, not hardware, which is why monthly costs run substantially lower than device-plus-SIM bundles.

Plans divide into two types. Rolling 30-day contracts carry no upfront cost, typically need no credit check, and let you exit with a month's notice. Fixed 12-month deals cost less per month but hold you to the full term. Both arrive as a physical SIM posted to your door, or activate as an eSIM, depending on your provider and whether your handset supports it.

UK prices start at around £3 per month [moneysupermarket.com.

That flexibility matters in practice, and not just for the money. Rolling contracts suit anyone who upgrades phones on their own timeline, wants to switch when a better deal appears, or simply dislikes locking in for a year. No penalty clauses, no fuss.

There's one angle most cheap SIM only deal guides skip entirely: what happens when you travel. Post-Brexit, most UK networks reintroduced EU roaming charges, and budget SIM plans frequently cap or throttle data abroad. Pairing your UK SIM with a dedicated travel eSIM is the more straightforward fix. HelloRoam's UK data plans start at ~£1.40 for 1GB over 7 days, with coverage across O2, Three, and Vodafone networks. For European trips, the [eSIM for Vietnam use the same per-trip pricing model.

But how low do UK prices actually go?

Which SIM is the cheapest in the UK?

![Hand holding an eSIM smartphone at a scenic Los Angeles viewpoint, comparing cheap SIM only deals

The cheapest SIM only deal in the UK as of April 2026 is Lebara at £1.78 per month for the first four months, rising to £6.90 thereafter, according to Money Saving Expert [moneysavingexpert.com. With over 60 SIM only deals live in the UK market at any given time [moneysupermarket.com, competitive introductory rates are common.

5G no longer costs extra.

Unlimited data now starts at around £8 to £12 per month from budget providers running on the same infrastructure as the big four networks. Unlimited with 5G comes in from around £15 per month [moneysupermarket.com. That same spec cost upwards of £25 just two or three years ago. The compression has been fast, driven by MVNOs consistently undercutting the big four on their own network capacity.

For light data users, a small-bundle rolling plan under £5 per month covers everyday browsing, maps, and messaging without much thought. For most people, that's the sensible starting point. Stream video or run a hotspot regularly and the unlimited tier makes more financial sense.

One structural caveat: the CMA blocked the Three/Vodafone merger in 2024, with proceedings still unresolved as of early 2026. Should that deal eventually complete, the competitive pressure holding these prices down could ease considerably.

Those prices depend on a specific market structure, and that structure is more interesting than it first appears.

Who has the cheapest SIM only contract?

![Flat lay of travel essentials and smartphone displaying cheap SIM only deals on a colourful background

No single provider holds the cheapest SIM only contract across all data tiers. The answer depends on usage: how much data, whether you make regular calls, and whether you travel.

That said, MVNOs (Mobile Virtual Network Operators, companies that lease capacity from the big four rather than running their own masts) consistently undercut EE, O2, Vodafone, and Three by 40 to 60 percent on equivalent plans [moneysavingexpert.com. SMARTY, GiffGaff, and iD Mobile sit at the sharper end of this market, offering 5GB to 30GB plans at prices the big four typically charge for their most basic allowances.

PAYG is different.

Pay-as-you-go suits occasional smartphone users, or anyone who relies mostly on Wi-Fi and only needs mobile data sporadically. No monthly commitment, no direct debit. The trade-off is predictable: data costs more per gigabyte and there's no unlimited option.

If you use 5GB or more per month, a rolling SIM only contract beats PAYG on cost without much contest. That saving is consistent and structural, which raises a question: whose masts is the budget provider actually using?

How MVNOs make cheap SIM only deals possible

![Woman in the desert using her smartphone beside a red 4x4, staying connected on a cheap SIM only deal

The assumption that budget MVNOs run on inferior networks is wrong.

SMARTY and iD Mobile operate on Three's masts [idmobile.co.uk. GiffGaff and Tesco Mobile run on O2's infrastructure [tescomobile.com. Lebara uses Vodafone's network [moneysavingexpert.com. The signal your phone receives is identical to a direct contract customer's in the same location, because it literally comes from the same tower.

MVNOs lease wholesale capacity from the big four. No towers to build, no spectrum licences to bid for, no high street retail estate to staff. Those structural savings pass directly to the customer, which explains why the pricing gap noted in the previous section is so consistent.

Coverage tracks the host network in almost all locations.

Edge cases exist. Some MVNOs restrict [international roaming or don't support it at all, and rural coverage in thin-signal areas reflects whatever the host network offers there. Checking your area against the host network's coverage map before switching takes about 30 seconds.

The host network breakdown:

• SMARTY and iD Mobile: Three masts (strong urban 5G, improving rural coverage)
• GiffGaff and Tesco Mobile: O2 infrastructure (wide rural reach, sound 4G performance)
• Lebara: Vodafone network (competitive urban and suburban coverage)

Each undercuts the host network's direct pricing, using the same masts with far lower overheads. The model has been reliable for years.

Credit history can still limit which contracts you're eligible for.

No credit check SIM options explained

![Hands holding a passport and smartphone with eSIM near luggage, ready to activate a cheap SIM only deal

Most rolling monthly SIM only deals require no credit check at all. That's the quiet relief many people miss when they assume phone contracts mean financial scrutiny. PAYG top-up plans go further still: no contract, no application, no approval process whatsoever.

GiffGaff and SMARTY both operate with minimal entry barriers. Neither runs a hard credit search for their rolling monthly plans, making them genuinely accessible if your credit history is thin, patchy from a recent move, or interrupted by time spent abroad.

The distinction matters.

A hard credit search leaves a visible mark on your credit file and can affect future applications. A soft assessment, which some 12-month fixed deals use, is invisible to other lenders. Rolling monthly plans typically skip the formal process altogether.

Twelve-month SIM contracts are a different story. Some providers run a soft credit assessment during sign-up, and a handful require a full hard check, particularly on deals with generous initial allowances or very low introductory rates. Read the small print before committing.

PAYG is the most frictionless entry point, but the per-gigabyte cost runs noticeably higher than a monthly plan. A no-contract rolling SIM threads that needle neatly: no commitment, no credit scrutiny, and data priced to compete with the bundles.

Those tradeoffs look different once you've set out the full picture of what you gain and what you give up.

Pros and cons of a cheap SIM only deal

![Car approaching airport departure signs, driver considering a cheap SIM only deal before travelling

Switching to a cheap SIM only deal can save between £100 and £300 per year compared with a traditional handset bundle [moneysavingexpert.com. The maths is straightforward, and for most people it settles the question. But there are real conditions attached.

The case for switching

The savings recur every year, not just at sign-up. A rolling monthly plan means you can leave any time, adjust your data tier without penalty, and shift to a competitor the moment a better deal emerges. Since budget MVNOs run on the same masts as the big four networks, as noted earlier in this guide, the quality compromise most people fear simply doesn't exist.

Flexibility is the headline benefit.

The catches

Your handset must be unlocked. A carrier-locked phone needs freeing before it'll accept a different SIM, a process that can take several days with some providers. Check this before you sign anything.

No handset upgrade path comes built in. SIM only is a commitment to the device you already own.

Roaming charges are the most overlooked downside. Budget MVNOs often carry limited EU roaming allowances, and post-Brexit, per-day bolt-on fees crept back for UK travellers across much of Europe. A travel eSIM alongside your UK plan is the practical fix for regular trips abroad: HelloRoam offers EU data plans starting from ~£1.14, with no surprise charges stacked on top.

Key fact: HelloRoam's Italy data plan starts from ~£1.14 for 1GB over 7 days, with 5G-capable network access.

For a short city break where your current carrier's EU roaming allowance covers the duration, a separate travel plan is overkill. A fortnight between capitals is a different calculation entirely.

Contract length shifts the financial balance significantly.

What are the benefits of 12-month contracts?

![Traveller holding passport and smartphone open to an eSIM app, exploring cheap SIM only deals

A 12-month SIM only contract typically unlocks a lower monthly rate than an equivalent rolling plan. Commit for a year and you'll usually pay less per gigabyte than someone on the same network's flexible tier.

Consider two customers on the same data allowance. The rolling monthly subscriber pays the standard rate, month by month, with full exit rights. The 12-month customer pays a fixed, lower rate, locked in regardless of what the broader market does. Over a year, that gap compounds.

That's not nothing.

Fixed terms also offer a degree of protection against mid-contract price increases. Some providers cap or exclude inflation-linked rises on fixed-length deals, a meaningful buffer if rates drift upward during your contract window. Rolling plans carry no equivalent protection: the price can shift with notice.

A handful of 12-month deals include improved EU roaming allowances compared with their rolling counterparts. If you travel within Europe several times a year, confirm the roaming terms at sign-up rather than discovering they're absent at the departure gate.

The case for rolling monthly is equally clear. Cancel any time, no early exit fees, and complete freedom to chase a better deal the moment one surfaces.

Switching is far simpler than most people expect.

How to switch to a cheap SIM only deal without losing your number

[Hand holding a mobile phone showing eSIM outdoors, demonstrating how to switch to a cheap sim only deal

Keeping your mobile number when you switch costs nothing and takes one text. Send PAC to 65075 from your current SIM and your provider must reply with your porting authorisation code within 60 seconds. Ofcom mandates this. They cannot delay, charge, or redirect you into a retention call before handing it over.

Send that text on a Tuesday morning and the code lands in your messages before you've finished your coffee. Hand it over at sign-up the same day, sleep on it, and wake up with the same number live on a different network: no phone call to your old provider, no negotiation, no waiting on hold.

Four steps to port your number

1. Text PAC to 65075. Your current provider replies automatically with your code. If they offer a deal to stay first, you're still entitled to the PAC regardless of whether you take it.
2. Give the PAC to your new provider at sign-up. Hand it over during the purchase process, not afterwards. This triggers the transfer.
3. Your number moves within one working day. Most transfers complete overnight, typically in the early hours.
4. Your old contract closes automatically. No separate cancellation is required. The number transfer triggers the contract end, and any remaining balance is calculated from that date.

Your PAC code is valid for 30 days from the date of issue. Miss that window and you simply text again for a fresh one.

Brief service interruption is possible during the transfer, usually limited to a few hours overnight. Users report it's rarely noticeable in practice. Don't discard your old SIM until the transfer confirms on your new device.

One practical point: if your current deal includes a minimum term, the PAC transfer overrides standard cancellation but early exit fees may still apply. Check your contract before you send that first text.

Will I lose service when switching networks?

![Blue SIM card on a dark background with red and purple lighting, representing UK network switching

The outage during a network switch is typically under two hours. Most transfers complete well within that window on a weekday, and plenty go through in under an hour.

The timing matters.

Port your number on a weekday morning and you're switching during off-peak processing hours, when transfers move fastest. Friday afternoon is a poor choice: ports submitted late in the week can sit queued over the weekend, stretching a two-hour gap into something considerably longer.

Most switchers don't realise the new SIM often activates before the old contract fully closes. There's a brief overlap where both are live, which means the dead zone is shorter than expected. Your new contract starts from the activation date, not the order date, so you're not billed for days you couldn't use.

Keep your old SIM in the phone until the new one connects, then you'll know the transfer is done. The practical upshot: text your PAC on a Tuesday or Wednesday morning, have the new SIM to hand, and allow a two-hour window where calls may not connect. In practice, it's usually over much faster.

Travelling abroad introduces a different problem entirely.

What happens to cheap SIM only deals when you travel abroad?

![Close-up of SIM cards and ejector tool on white background, showing what happens to cheap SIM only deals abroad

Post-Brexit roaming charges apply on most UK plans, and the cheapest SIM only deals are often the least generous when it comes to EU coverage. Some carriers have reintroduced daily roaming add-ons costing £1 to £2 per day in Europe [uswitch.com. Others include limited EU data but throttle speeds sharply once a fair use cap is hit.

Ten days in Spain at £2 a day adds £20 to your bill before you've opened a single map. Budget MVNOs sometimes skip EU roaming entirely, leaving you on pay-as-you-go rates the moment you land.

A travel eSIM installed alongside your UK SIM sidesteps the roaming charge problem entirely. Your UK number stays active on the physical SIM (useful when your bank fires off a verification text), while local data runs through the eSIM at local rates. Most modern smartphones support dual SIM, which makes the setup straightforward.

Budget SIM plans are excellent value for day-to-day use at home. Cross the Channel and the economics shift fast, and your carrier is rarely the one to flag it.