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Compare SIM only mobile deals

Reviewed by the Smart Comparison editorial team · Updated July 2026

Compare the best SIM only deals from the UK's leading networks. Updated daily.

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Prices correct as of August 2026. We may earn commission when you click through — this never affects our rankings.

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What is a SIM only deal?

A SIM only deal gives you a monthly bundle of data, calls and texts without the cost of a new handset. You keep your existing phone and just pay for the plan — which makes it significantly cheaper than a standard pay monthly contract. Most people could save over £200 a year by switching from a handset contract to an equivalent SIM only plan.

One thing many people do not realise is that when a pay-monthly contract ends, most networks automatically move you onto a rolling SIM only plan — often not on the best available rate. It is always worth comparing deals at that point rather than letting your plan roll over unchecked.

How much data do you actually need?

Most people overestimate how much data they need. According to Ofcom, the average UK mobile user consumes around 10GB per month — but the majority of people use considerably less.

Usage typeMonthly dataWhat it covers
Light userUnder 3GBBrowsing and social media mostly on Wi-Fi
Average user3 to 10GBStreaming music, occasional video on the go
Heavy user10 to 30GBRegular video streaming, working remotely
Very heavy user30GB+Constant streaming, no home broadband

30-day vs 12-month contracts

The two most common SIM only contract lengths are 30-day rolling plans and 12-month contracts. Here is how they compare:

30-day rolling
  • ✓ Cancel anytime
  • ✓ No long-term commitment
  • ✓ Usually no credit check
  • ✗ Slightly higher monthly cost
12-month contract
  • ✓ Lower monthly price
  • ✓ Good balance of value and flexibility
  • ✗ Locked in for 12 months
  • ✗ May have annual price rises

Watch out for annual price rises

Many of the major networks apply an annual mid-contract price rise, typically in April. Several networks including Smarty, giffgaff, VOXI, iD Mobile and Lebara currently offer deals with no in-contract price rises.

NetworkPrice rise policy
O2Annual rise each April, currently £2.50/month
VodafoneAnnual rise each April, currently £1.50/month
ThreeAnnual rise each April, currently £1.90/month
EEAnnual rise each April, linked to CPI + 3.9%
Smarty, giffgaff, VOXI, iD Mobile, LebaraNo mid-contract price rises

What are MVNOs?

Most of the networks on this page are MVNOs — Mobile Virtual Network Operators. They buy capacity from one of the big four (EE, O2, Three or Vodafone) and resell it at a lower price. The signal travels through exactly the same masts — there is no technical difference in coverage.

NetworkRuns on
giffgaffO2
SmartyThree
VOXIVodafone
iD MobileThree
Asda MobileVodafone
LebaraVodafone

How to switch and keep your number

1
Check your contract end date
Text INFO to 85075 to receive your contract end date and current monthly spend. If you still have time left, leaving early may incur an exit fee.
2
Get your PAC code
Text PAC to 65075 (free). Your current network must send it within one working day. This lets you take your number to a new network.
3
Choose a deal above
Select a deal and click through to the provider's website to sign up. You will need to pass a credit check for 12-month contracts.
4
Give your PAC code to your new network
Pass the PAC code when signing up. Your old plan will be cancelled automatically when the transfer completes — usually within one working day.

Frequently asked questions

Are SIM only deals cheaper than phone contracts?
Yes. With a SIM only deal, you only pay for your data, calls and texts — not the cost of a handset. Monthly bills are typically much lower as a result. Most people could save over £200 a year by switching from an expiring handset contract to an equivalent SIM only plan.
Do I need to pass a credit check?
For 12-month and 24-month contracts, most networks will run a credit check. For 30-day rolling plans, approval is usually faster with less stringent checks. Smarty, giffgaff and Lebara all offer no-credit-check plans.
Can I keep my phone number when I switch?
Yes. Text PAC to 65075 to get your Porting Authorisation Code. Give this to your new network when signing up and your number will transfer automatically — usually within one working day.
Do SIM only deals include 5G?
Most modern SIM only deals include 5G at no extra cost, provided you have a 5G-compatible handset and live in an area with 5G coverage.
What is an eSIM?
An eSIM is a digital version of a SIM card built into your phone. You activate a plan directly on your device without needing a physical card. Most modern smartphones including iPhone 14 and later support eSIMs.
Do SIM only deals include roaming?
Many networks include EU roaming at no extra cost. Some networks like Lebara and Three also include roaming in a wider range of destinations. Always check the roaming terms before signing up if you travel frequently.
Quick links
Expert tip

If you are nearing the end of your contract, switching to a SIM only plan could reduce your bill dramatically — you will no longer pay extra for a handset you have already paid off.

Check coverage

Before switching networks, check coverage at your address using Ofcom's free tool.

Check coverage
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