Methodology: how MobiSaver checks facts and does the sums

How we check facts

Primary sources first. Rules come from Ofcom (including the General Conditions and its guidance), the FCA and GOV.UK. Network details come from each brand's own price guides, terms, price-change pages and help pages. Phone prices come from the manufacturer or seller.
Secondary sources are labelled. Where a primary source didn't settle a question, we used reputable secondary sources such as MoneySavingExpert or ISPreview, and say so next to the fact.
Real dates. "Checked" means we looked at the source on that date. Everything in the first edition of the site was checked on 8 November 2026. We haven't set up a regular re-check, so read every figure as true on its check date.
Gaps stay visible. We keep four outcomes apart: confirmed, only confirmed by a secondary source, conflicting sources, and unknown or unavailable (a page we couldn't read). None of these is quietly turned into a "yes" or a "no".
Examples are dated. Every price in a worked example is tied to the day we saw it and the terms on the page. If an offer couldn't be confirmed, we removed it or said so instead of substituting another price.

Corrections made before publication

Our draft articles were checked line by line on 8 November 2026. Among the changes: the Google Store was selling the Pixel 10a at £399 (usually £599) during an offer, so that example was re-worked; an iD Mobile contract and a 10GB SIM plan in the draft couldn't be found and were replaced with deals we could see; refurbished prices from Back Market couldn't be read, so they are not used; VOXI's roaming passes, giffgaff's no-rise promise, 1pMobile's price policy and several roaming caps were corrected from the brands' own pages; and exit-fee examples for O2, giffgaff and Sky Mobile were added from their published methods.

The true cost calculator

The true cost calculator compares up to five ways to pay for a phone over one period you choose (12 to 48 months). It starts empty: every price is one you enter.

Payments. Monthly plans are charged on the same day each month. A plan that renews every 30 days is charged on its actual renewal dates, which adds about one payment a year.
Price rises. A fixed rise (for example £2.50 a month) applies from the month you choose, every year after your first payment. You can tell it to skip the first rise if your provider does. Rises on a contract apply during the minimum term; after it you choose whether you keep paying the last contract price or move to a price you enter.
Commitments that outlast the period. If a contract or finance agreement runs past the end of the period, the amount still owed is added to that route: the remaining contract payments, or the remaining balance on a finance agreement (an approximation of the early settlement figure; your lender's figure may differ slightly). Leaving it out would make long agreements look cheaper than they are.
Finance. With an APR, instalments are worked out as a standard repayment loan, using a monthly rate equivalent to the APR. If you enter the instalment stated in your agreement, that figure is used as given.
The phone is counted once. On the finance route the phone is paid through the instalments; on the outright and refurbished routes, through the purchase price.
Resale and cashback. A resale value is subtracted only if you enter one; we don't publish a database of resale values. Cashback you have to claim is shown separately and never included in the total.
Results. For each route: the total over the period, the cost per month (total divided by the number of months), and how each part adds up. Routes are ranked by total; routes within a penny are shown as equal.
Break-even. The chart shows the cash paid so far, month by month. A break-even month is shown only where one route that started dearer becomes cheaper and stays cheaper. If that doesn't happen within the period, the calculator says so.
Not included: insurance, interest you could earn on savings, late fees, credit decisions or eligibility. It doesn't recommend credit products.

The leave-now-or-wait calculator

The leave-now-or-wait calculator compares two choices over the same period: leave on the date you enter, or stay until your minimum term ends and move to the same new deal then.

Part-months are charged pro rata, as a share of the calendar month.
Price rises you enter start on the date you give.
Exit fee. Best is the figure from your INFO or PAC text. For EE, O2 airtime plans, Vodafone, Three and giffgaff 18-month plans it can estimate the fee from the method each network published, checked on 8 November 2026 (remaining charges less 4%, 4%, 2% and 3% respectively; giffgaff 50% of the plan price for each full month left). The estimate uses your current price and ignores add-ons and account credit, and is always labelled as an estimate. We don't estimate for networks whose method we couldn't confirm or which use per-plan tables. If you don't know the fee, it is never treated as zero: you get the fee below which leaving would be cheaper.
Right to leave after a change. If you tell it your provider notified a change, it shows a separate "if your right to leave is confirmed" result and an indicative deadline one month after the notice. It doesn't decide whether the right applies; your contract and the notice do.
Device plans. A separate device plan is owed whichever you choose, so it doesn't change the cost difference; if the balance becomes due when you leave, it's included in the cash you'd need on the day.
Calendar file. The optional .ics file is created in your browser. There are no email reminders.

The network comparison data

The network table and its CSV and JSON downloads are generated from one data file. Each value carries a status, the plans or customers it applies to, its sources and the check date. Filters only count a brand as a match when the value is confirmed (and, if you choose, when it comes from a secondary source); unknown, unavailable and conflicting values are left out and counted separately.

What MobiSaver doesn't do

We don't take payment for coverage, use affiliate links or show adverts. Our guides are general information, not financial or legal advice.