SIM only prices change often enough that a specific number quoted in a blog post is usually out of date within days or weeks. Rather than list prices here that may already be wrong by the time you read this, this guide covers what actually makes a SIM deal cheap for your situation — so you can evaluate today's live deals properly, wherever you're comparing them.
For current prices, our SIM only comparison page updates as deals change. This guide covers how to pick the right one once you're looking at it.
Get the data allowance right first
The single biggest factor in whether a deal is genuinely cheap for you — more than the headline price — is whether the data allowance matches what you actually use. An unlimited data plan is not automatically the cheapest option; it carries a premium because the network is pricing in worst-case usage. If you mostly use Wi-Fi and only need mobile data for maps, messaging and occasional browsing, a 10-20GB plan will usually work out significantly cheaper per month for data you'd never have used on an unlimited plan anyway.
A rough way to check: look at your current phone's data usage in settings over the last month or two, add some headroom, then compare deals around that allowance rather than defaulting to the biggest number on offer.
Rolling (30-day) vs fixed-term contracts
Cancel or switch with 30 days' notice, no exit fees. Usually no credit check. Lets you jump to a cheaper deal as soon as one appears, rather than being locked into today's price for a year or two. The trade-off is the monthly price is sometimes very slightly higher than an equivalent fixed-term deal.
Often a marginally lower monthly price in exchange for committing to the full term — leaving early usually means an exit fee. More likely to involve a credit check. Worth it if you're confident you won't want to switch, but it also means you can't take advantage of a cheaper deal appearing next month.
If you're not sure which suits you, rolling is the lower-risk default — the price difference versus a fixed-term deal is usually small, and the flexibility to switch the moment something cheaper appears often outweighs it.
No-credit-check options
If you have limited or poor credit history, rolling 30-day SIM only plans are generally the most accessible route, since there's no borrowing involved for the network to assess. Several MVNOs built their whole model around straightforward, no-credit-check rolling plans:
How to find the cheapest deal today
Once you know roughly what data allowance you need and whether you want rolling or fixed-term, the fastest way to find the actual cheapest live option is to compare current prices directly rather than search for "best deals" articles, which are frequently outdated by the time they're published. A few things worth checking on any deal before signing up:
- →Whether the price shown is permanent or an introductory rate that rises after a set number of months.
- →What happens automatically when a fixed-term contract ends — some networks roll you onto a higher default price rather than ending the service.
- →Whether the network offers 5G if that matters to you, since some budget MVNOs are 4G-only.
- →Any minimum spend, EU roaming allowance, or data rollover differences if those affect how you'd actually use the plan.
Compare current SIM only prices
Prices update as deals change — filter by data allowance and contract length to see what's genuinely cheapest for your needs right now.
Compare SIM only deals →Frequently asked questions
Is the cheapest SIM deal always the one with unlimited data?
No — often the opposite. Unlimited data plans carry a premium because the network is pricing in worst-case usage. If you use less than around 10-15GB a month, a capped-data plan is usually meaningfully cheaper for the same or better price-per-GB. The cheapest deal for you depends on matching the allowance to what you actually use, not picking the biggest number available.
Do I need a credit check for a SIM only deal?
It depends on the contract length. Most 30-day rolling SIM only plans don't require a credit check, since you're not being extended any credit — you pay for the month ahead, and either side can walk away with 30 days' notice. Fixed-term contracts (12 or 24 months) more commonly involve a credit check, even for SIM only, since you're committing to a longer-term agreement.
What's the catch with very cheap SIM deals?
Usually there isn't one, but it's worth checking three things: whether the advertised price is a temporary introductory rate that rises after a few months, what happens automatically at the end of a fixed-term contract (some roll onto a higher default price rather than ending), and whether the network uses 4G-only infrastructure if you specifically need 5G. None of these make a deal bad, but they affect whether the advertised price is the price you'll actually pay long-term.
How often do SIM only prices actually change?
Frequently — networks adjust pricing and promotional offers on an ongoing basis, sometimes weekly. This is exactly why it's worth checking live current prices rather than relying on a number you saw even a few weeks ago; a deal that was the cheapest last month may no longer be available or may have been undercut by a new offer.
Get the best deals in your inbox
No spam — just the cheapest mobile and broadband deals, updated weekly. Unsubscribe anytime.