The calculation to use
Start with this: upfront cost + all monthly payments during the minimum term + paid extras - guaranteed cashback. The result is the minimum total you expect to pay, before out-of-allowance use.
For example, imagine a 24-month deal costs £99 upfront, £29 a month for the first year and £31 a month for the second. The total is £99 + £348 + £372 = £819. A competing deal at £33 a month with no upfront fee totals £792, so its larger monthly number is actually cheaper overall.
Include every stated price change
For new consumer contracts from 17 January 2025, providers must show any in-contract price rises in pounds and pence before the customer signs up. That makes the calculation clearer, but you still need to include each scheduled amount rather than multiplying only the first month's price.
Read the contract summary and information documents. Ofcom requires important details such as price, contract length, services and early-exit charges to be provided clearly before the contract is agreed. Keep a copy so you can check later promises against the actual terms.
Separate the phone from the airtime
Some deals use separate handset and airtime agreements. Ask how long each part lasts, whether the airtime price changes after the phone is paid off, and what happens at the end of the minimum term. Continuing to pay the same amount without reviewing the deal can become expensive.
Compare the contract total with buying the handset outright and using a SIM-only plan. The contract can still be the right choice because it spreads the cost, but financing convenience and lowest total price are different benefits.
Check what you are actually receiving
- Data: use recent bills or your network app to see what you normally consume. Unlimited data has little value if you regularly use 8GB.
- Storage and model: confirm the exact phone, capacity, colour and whether it is new or refurbished.
- Extras: identify trials, streaming services, insurance and accessories that later become paid subscriptions.
- Coverage: check service where you live, work and travel. A cheap allowance is poor value if the network is unreliable in the places that matter.
- Leaving early: understand the minimum term and early termination charge before choosing a long agreement.
Protect yourself from unexpected bills
UK mobile customers can ask for a bill limit when entering a contract, and providers must notify customers as a limit is approached. A suitable limit can reduce the risk from out-of-allowance data or calls, although it does not replace checking what is and is not included.
Before paying, write the real total beside each shortlisted deal. This one-minute step turns a confusing wall of monthly figures into a fair comparison.