The cheapest-looking phone is not necessarily the cheapest phone to own. A fair comparison includes every required payment, realistic optional spending and the value left in the device when you finish with it.
The calculation
Net ownership cost = acquisition + airtime + mandatory fees + accessories + cover + repairs − money recovered at the end.
Keep the phone and airtime separate even when a network presents them as one monthly amount. Also keep guaranteed payments separate from provisional cashback or trade-in values.
| Cost line | What to enter | Common mistake |
|---|---|---|
| Phone | Cash price or all device instalments | Using only the deposit or first monthly payment |
| Airtime | Every core subscription payment over the chosen period | Assuming the current monthly figure never changes |
| Mandatory fees | Delivery, connection or unavoidable checkout charges | Adding them only after choosing the deal |
| Accessories | Only items required for safe and practical use | Treating every add-on as essential |
| Insurance and repairs | Premiums, excesses and a realistic repair reserve | Counting insurance as if every event will be covered |
| Residual value | Conservative net cash after fees and postage | Using the highest current asking price as a future guarantee |
Illustrative comparison
Suppose Option A requires £620 for the phone, £360 of airtime, £45 of accessories and an £80 battery replacement, with £140 recovered at sale. Its illustrative net ownership cost is £965.
Option B costs £34 a month for 36 months, has a £29 upfront payment and is expected to return £160 at sale. Before extras, its illustrative net cost is £1,093. These figures are examples only; use current written prices for the exact deals.
Add a repair and exit scenario
Run the calculation twice: once if everything goes to plan, and once if you need an ordinary repair or leave a contract early. The second result reveals whether a superficially cheap route is fragile.
Check whether the phone can last for the chosen period
Price per year is meaningful only if the model remains secure, usable and repairable. Check the manufacturer’s published security-update period, storage, battery service and parts position before assuming a four- or five-year life.
Record assumptions
- Ownership period and expected sale month
- Current contract price and every stated rise
- Estimated repair reserve
- Expected resale method and selling costs
- Which figures are guaranteed and which are illustrative
Three versions of the answer
Keep three totals in the worksheet. The contractual minimum contains every payment you must make if nothing unusual happens. The likely ownership cost adds realistic accessories and maintenance. The adverse scenario adds an ordinary repair, a lower resale result or an early-exit balance. A deal that looks attractive only in the optimistic version is not a robust choice.
When to update the calculation
Repeat the calculation when a retailer changes the price, the network issues a contract summary, a trade-in quote expires or the planned ownership period changes. Keep screenshots or PDFs of the figures used so the final decision can be checked later.
Compare different ownership periods fairly
A cheaper annual figure is meaningful only when the phone can realistically remain secure and useful for that period. Compare the same number of months, then divide the net ownership cost by the years of expected use. Do not extend a model’s assumed life merely to make its annual cost look attractive.
| Cost type | Examples | How to treat it |
|---|---|---|
| Fixed and committed | Phone price, device instalments, core airtime and mandatory fees | Include in the contractual minimum. |
| Likely but variable | Case, charger, battery service and ordinary repair reserve | Use a realistic scenario rather than zero. |
| Optional protection | Insurance premiums and excess | Include only when you would actually buy the cover. |
| Recoverable value | Trade-in or private-sale proceeds | Use conservative net cash, separately from guaranteed payments. |
Do not force a resale assumption
If you normally keep phones until they have little value, use zero or a modest recycling outcome rather than an optimistic resale estimate. If resale is part of the plan, state the expected condition, selling method, fees and month of sale. A residual-value figure without those assumptions is not a usable comparison.
Set a replacement trigger before buying
Decide what would justify replacement: the end of security support, a repair that exceeds a chosen proportion of the phone’s remaining value, insufficient storage for essential use, or repeated downtime. This prevents a new-phone launch or temporary discount from becoming the reason to abandon a device that still meets the original plan.
Keep the calculation with the purchase documents and update it when a contract, repair quote or resale plan changes. A recorded decision is easier to review than a remembered headline price.
Related guides
- How Much Does Phone Ownership Really Cost?
- Monthly Phone Costs Breakdown
- How Phone Depreciation Works
Sources and date checked
Official information checked 26 July 2026. Product prices, contract terms and retailer policies can change, so verify the current document before acting.
