Our methodology
How we judge a phone deal
Phone contracts roll the cost of the handset into your monthly airtime bill, so a genuinely good deal can look much like an overpriced one. The Fair Value Score cuts through that with a single number, answering one question: is this contract cheaper, or dearer, than simply buying the same phone yourself?
What we actually compare
Every contract is measured against the most sensible do-it-yourself alternative: buying the exact same phone outright and pairing it with the cheapest SIM-only plan that carries the same data. That do-it-yourself cost is our benchmark — beat it and the contract is good value; fall short of it and you're paying a premium for the convenience of spreading the cost.
To make that comparison fair, we adjust for three things:
Count every pound
We total the upfront cost and every monthly payment over the full term — including the rise most networks apply each April, any introductory discount, and any cashback. Adverts often quote a figure that leaves the April rises out; we add them back in.
Value it in today's money
A pound paid in two years is worth less than one today, because money kept in the meantime could be earning interest (we assume around 4.5% a year). So we scale every future payment back to today's value — and treat the DIY route exactly the same way.
Only count genuine extras
A "free" trial you'd get anyway when buying the phone yourself saves you nothing, so we ignore it. We only count perks the do-it-yourself buyer would miss out on — a Disney+ subscription thrown in by the network, say.
Turning that into a score
The Fair Value Score expresses the do-it-yourself cost as a percentage of what the contract really costs you:
Fair Value Score = 100 × do-it-yourself cost ÷ true contract cost
- 100 — the contract costs the same as doing it yourself.
- Above 100 — doing it yourself would cost more, so the contract is the better-value choice.
- Below 100 — the contract costs more than doing it yourself, so you're overpaying.
Every score is fully reproducible — open any deal's breakdown to see these figures laid out in full. The Fair Value Score is our assessment of value for money, not financial advice.
A worked example
Take a 36-month deal for the Apple iPhone 17 Pro Max 256GB. Here's the contract, the do-it-yourself alternative, and what the Fair Value Score makes of it.
The contract
- Upfront
- £50
- Monthly (£34.75 phone + £27 airtime)
- £61.75
- Airtime rises (2027 / 2028)
- £64.25 / £66.75
- Data
- 30GB 5G
Do it yourself
- Same phone, SIM-free, bought outright
- £1,199
- Cheapest matching SIM (50GB, same network)
- £7.95/mo
- Price rises
- None
Where your money goes
The same handset is valued at its SIM-free price on both sides, so the gap between the bars is the airtime.
Doing it yourself saves £893 — and it is all airtime, not the phone
Valued in today's money (after discounting)
≈ £2,230 vs £1,470 DIY
FVS = 100 × £1,470 ÷ £2,230 ≈ 66
The contract costs about £893 more in cash — or £760 more in today's money once future payments are discounted. The handset is only ~£100 dearer than buying it outright; the rest is the 30GB plan at £27–£32 a month versus £7.95 for a 50GB SIM on the same network.
Illustrative figures, discounted at 4.5% a year.
Try it yourself
The calculator below runs the same comparison, in pounds. Enter a contract to see its true total and its value in today's money, then tick Compare with SIM-only to weigh it against the do-it-yourself route.