Mobile
SIM Only or a Phone Contract? How to Compare the Real Cost
A phone contract puts the handset and the plan into one monthly price for a fixed term; SIM only is the plan alone. Compare the two totals over the same months, including anything paid upfront and any rise the contract states.
- Compare over the same months
- Rises stated in pounds and pence
- UK network phones are unlocked
Current plans from the providers Wisemium works with, as each seller states them.
SIM only or contract
- Paid on the day
- Phone price, or the upfront payment
- Each month
- SIM plan, or one contract price
- Tied to a network
- No, or for the whole term
How the two routes differ. Your own figures go in the calculator below.
Work out both totals over 24 months
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The full guide
A phone contract puts the handset and the mobile plan into one monthly price for a fixed term. SIM only is the plan alone, for a phone you already own or buy outright. The fair comparison is the total over the same number of months, including anything paid upfront.
How the two compare
| Phone contract | SIM only | |
|---|---|---|
| What you pay for | The phone and the plan together | The plan; the phone is separate |
| Usual term | 24 or 36 months | 30 days, 12 or 24 months |
| Paid upfront | Sometimes, as stated | The phone price, if you buy one |
| Credit check | Yes, for the phone part | Usually for a 12 or 24 month plan |
| Changing network | Tied for the term | As often as the term allows |
Work out both totals
For the contract: the monthly price times the months, plus any upfront payment, plus any rise the contract states. For SIM only: the phone’s price, plus the SIM plan’s monthly price times the same months. If you are keeping a phone you already have, the SIM only total is the plan alone.
Price rises during the term
Since January 2025, a new mobile contract must state any price rise during the term in pounds and pence, not as a percentage linked to inflation. Add those rises to the total before you compare.
Unlocked phones
Networks have not been allowed to sell locked phones in the UK since December 2021, so a phone bought on a contract can take another network’s SIM. A phone bought outright from the maker is unlocked too.
When the term ends
A phone contract does not stop at the end of the term: it rolls on monthly. Check whether the price drops once the phone is paid for. Mobile contract ending covers the notice your network sends and how to keep your number.
How Wisemium helps
Wisemium lists SIM only plans and phones from the providers it works with, not every plan on the market, with each seller’s price, upfront payment and stated rises. Add the plan you choose and its end date is kept on record.
Current plans from the providers Wisemium works with, as each seller states them.
Common questions
Is SIM only cheaper than a contract?
Often, if you keep a phone you already own. If you need a new phone, compare the phone’s price plus the SIM plan against the contract total over the same months.
Do I need a credit check for SIM only?
Usually for a 12 or 24 month plan. A 30-day rolling plan may still involve a check; pay as you go does not.
Can I put a SIM only plan in a contract phone?
Yes, if the phone is unlocked. Phones sold by UK networks since December 2021 are unlocked.
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