Cheap UK SIM-Only Deals: What Is Actually Good Value?

The short answer

Good value is personal, but the maths is not

If you use less than 5GB a month, a £20 unlimited plan is not generous. It is a monthly donation to a telecoms company. If you tether a laptop every day, the £5 option may be cheap only until the first data add-on.

For ordinary UK data, 1pMobile and SMARTY currently make a strong price case. 1pMobile advertises 5GB for £5 and 50GB for £10 on 30-day plans, while SMARTY lists 5GB for £6, 40GB for £10 and unlimited data for £20 on rolling monthly plans.⁵³

Lebara deserves a separate look if you call abroad or want its included roaming benefits. Its rates page says all plans include an international-call allowance to more than 50 countries, while its public deals page starts at £5 before any referral saving.¹⁰¹ Open the referral route, then check that the advertised 50% introductory price, allowance and renewal price all appear before paying.

See the live Lebara referral price ↗

The useful shortlist

What the official plan pages are advertising

This is a snapshot, not a promise. Promotions, allowances and renewal terms move. Treat each row as a sensible place to start, then confirm the final basket.

Do not compare a temporary boosted allowance with another provider's permanent allowance as though they are the same product. Note the offer end, the allowance after it ends and the price you will actually keep paying.

A number your phone already knows

Find out how much data you really use

Ignore online quizzes that ask whether you are a "light browser". Your phone has a better answer.

1. Open mobile-data settings.On iPhone, look under Settings and Mobile Service. On Android, search Settings for data usage.
2. Use a complete normal month.A holiday, house move or week of broken broadband will produce a heroic but unhelpful number.
3. Add a modest cushion.You need room for an unusually busy week, not enough spare data to stream the King's Christmas message in 8K.
4. Check tethering separately.Laptop updates and video meetings can change the answer quickly.

The crowded middle

Ten pounds buys wildly different things

At the time of this check, £10 buys 20GB on giffgaff's rolling plan, 40GB on SMARTY, 50GB on 1pMobile and a promotional 60GB on VOXI. The last offer is presented as three times a 20GB base allowance, so the big number needs an expiry check.²³⁴

Raw gigabytes do not settle it. giffgaff may win if O2 is the only network that behaves inside your flat. VOXI may win for someone whose eligible social use consumes most of their data. 1pMobile's straightforward 50GB may be better for a person who wants plenty of general data without decoding app lists.

If calls abroad matter, compare Lebara on the total package rather than gigabytes alone. Open the offer, choose the smallest allowance that fits, then check the included destinations and final renewal price.

Where cheap comparisons go wrong

Count extras only when they replace something you buy

An eSIM is useful if you need service quickly or keep two lines. EU roaming matters if you travel. International minutes matter if you call normal overseas numbers. Unlimited social data matters only if your actual apps and activity qualify.

Otherwise, an extra is a brochure ornament. It should not persuade you to spend another £4 every month.

Unlimited data needs a reason

SMARTY and giffgaff both currently list unlimited rolling options at £20, although giffgaff marks its price as a limited promotion. 1pMobile lists unlimited at £25 and says speeds may be slowed at busy locations after 500GB in a boost period. VOXI lists unlimited at £35.³²⁵

Unlimited makes sense for heavy tethering, frequent high-quality video away from Wi-Fi or replacing fixed broadband. If you use 12GB, paying for infinity is mathematically impressive and financially pointless.

The non-negotiable bit

A dead zone makes every allowance zero

Check predicted coverage at home, work and the places where you spend time indoors. Ofcom's checker separates outdoor and in-home predictions for EE, O2, Three and Vodafone. It also warns that buildings, trees and wall thickness can make real experience differ from the map.⁷

Smaller mobile brands use one or more of those main networks. giffgaff says it is powered by O2, while VOXI's current page describes service on the combined Vodafone and Three network.²⁴ Check the provider's current host-network information because arrangements can change.

A rolling plan reduces the pain of a bad choice, but it does not remove the nuisance. Test data, calls and indoor reception before moving your main number.

Leaving should be boring

Switch without paying twice

First, text INFO to 85075 if you need to check your contract position and possible exit charge. To keep your number, text PAC to 65075. To leave without keeping it, text STAC to 75075.⁶

Ofcom says the code is valid for 30 days and the new provider must normally complete the switch within one working day after receiving it.⁶ Activate and test the new service first when the provider allows it. Nobody enjoys troubleshooting account access while both SIMs are in a drawer labelled "probably old".

Quick answers

Questions before choosing