A contract SIM is a price plus a period, and the period is what you are actually buying. The headline is almost always lower than the rolling monthly equivalent, and in the UK it is almost always allowed to rise during the term, so the number to compare is the average over the whole period rather than the figure in the first month. Two sellers in this record publish a term on the page we read, and one of them publishes the rise too, which makes the arithmetic possible for once.
What the published terms cost
Vodafone publishes unlimited data at £23 a month on a 24 month plan and states Save £288 with a 24-month plan, which is a comparison with its own shorter option rather than with the market. Lycamobile prints 12 month and 24 month plans beside its 30 day ladder, where unlimited is 12.5 GBP over 30 days, and describes the longer terms as discounted. The three other sellers whose pages could be read sell rolling monthly: SMARTY from £6 to £20 with no tie, Ecotalk on one month terms at £12.00 to £22.00, and Utility Warehouse on from prices of £5 and £23.
Adding the rise before you compare
Vodafone publishes the increase as a figure, which is rare and useful: £2.50 for Pay monthly Airtime and Data plans each April, and on the unlimited plan specifically that it increases to £25.50 on 1 April 2027 and £28 on 1 April 2028. A plan advertised at £23 that spends part of its term at £25.50 and part at £28 averages well above its headline, and the honest comparison against SMARTY's untied £20 is that average rather than the first month. Nothing here says the term is a bad deal; it says the number on the page is not the number you pay.
What you buy with a rolling month
A rolling monthly plan can be repriced too. The difference is that you can leave the month it happens, and leaving costs nothing because there is nothing to end early. That optionality is worth a real amount in a market that raises prices on a schedule, and it is why a rolling £20 and a tied £23 are closer than the numbers suggest. If you take a term anyway, take it knowing the exit price: the PAC text quotes the early termination charge, which is the figure that decides whether leaving early is worth it.
Questions people ask about contract sim
What does a contract sim cost in the UK?
Vodafone publishes £23 a month for unlimited data on a 24 month plan, and Lycamobile prints 12 and 24 month plans beside its 30 day ladder. Rolling monthly plans in this record run from £5 to £23.
Does the price rise during the contract?
Usually. Vodafone publishes a £2.50 April increase for pay monthly airtime and data plans, and that its unlimited plan increases to £25.50 on 1 April 2027 and £28 on 1 April 2028.
Is a sim contract deal cheaper than rolling monthly?
On the headline, usually. Over the term, often not once the published rises are counted, and a rolling plan can be left the month a rise lands.
What does it cost to leave a contract early?
The early termination charge is quoted in the text you get when you request a PAC code, along with the code itself. That is the cheapest way to find out and it does not commit you to leaving.