The iPhone 18 Pro event is expected around 8–9 September 2026. That gives you roughly eight weeks to sell your iPhone 15 or 16 at a price that still makes sense. Miss that window and you'll be selling into a market that has already moved on.
Why September is the cruelest month for older iPhone values
Apple's launch calendar is one of the most predictable forces in the used-phone market. Every year, the same thing happens: rumours build through July and August, buyers start holding off purchases of older models, and then the moment Apple takes the stage, prices fall.
The data from Compare and Recycle is clear: older iPhones lose an average of 9% of their value immediately after Apple announces a new model, and a further drop of around 20% follows once the new devices are actually released. That is not a gradual slide — it happens within days.
Timing calculators back this up. iPhone values peak in the two weeks before Apple's annual September event, when demand for current models is still high and supply is constrained. Within 48 hours of the announcement, used prices on the outgoing model drop 8–15% as buyers hold out for the new generation.
Where the iPhone 15 stands right now
The iPhone 15 launched in September 2023 at £799 for the base 128GB model. As of mid-2026, a 128GB iPhone 15 in good condition has depreciated by around 66% since launch. That is steep — and it is accelerating.
The underlying trend is not encouraging either. At this stage of its lifecycle, the iPhone 15 is losing roughly £10–15 in resale value every single month — that is not scaremongering, it is just how phone depreciation works once a model is two generations old.
The iPhone 15 series has form for sharp falls. The iPhone 15 series depreciated by 55.57% on average in its first year — the steepest first-year drop of any iPhone generation at that point. Now entering its third year, the rate is not improving.
There is a further pressure building right now that is specific to 2026: Apple is deviating from its standard launch timeline this year. Instead of four new iPhones in September, the iPhone 18 lineup will come out across autumn 2026 and spring 2027, with the more expensive iPhone 18 Pro and Pro Max launching in September. The headline event — and the headline depreciation hit — still lands in September, as usual.
The iPhone 16 situation is different, but the timing logic is identical
If you own an iPhone 16, the picture is less dire in absolute terms, but the timing argument is the same. The iPhone 16 128GB has depreciated by around 49% since its 2024 launch if sold in good condition. It has held its value noticeably better than the 15 series did at the same age — the iPhone 16 series averaged 45.07% first-year depreciation, the first lineup in three years to show a decreased rate compared to its predecessors.
That relative resilience, though, disappears quickly once the iPhone 18 lands. Apple traditionally announces new iPhones in September, and the best time to sell an iPhone 16 is mid-to-late August — once the new models are officially announced and hit shelves, the market floods with older devices from people upgrading, which temporarily drives down resale value.
The window to act is right now, not in a fortnight.
How much will my iPhone lose value after the iPhone 18 announcement?
Based on every Apple launch cycle since 2018, expect a two-stage hit. The announcement alone typically knocks 8–10% off the resale value of outgoing models within 48 hours. Then, once the new phones are physically on shelves — expected around Friday 18 September, with pre-orders opening around 11 September — a further drop of around 20% tends to follow as the secondary market floods with upgrade trade-ins. Combined, older iPhone models lose an average of 9% on announcement, then a further roughly 20% after release. For an iPhone 15 currently worth £200–£280 depending on model and condition, that is a real-money loss of £50–£80 in a matter of weeks.
Is it too late to sell my iPhone 15 for a good price?
Not yet — but the margin for error is shrinking. The optimal window for iPhone resale is roughly four to six weeks before a September launch event, when used demand is still strong and the announcement hasn't reset buyer expectations. With today being mid-July, that window is open but not wide. The iPhone 17 range has already pushed the 15 further down the pecking order, which means right now, in 2026, is still a decent window to sell before values drop further. Wait until August and you are cutting it fine. Wait until September and you have likely missed the peak entirely.
What actually affects the price you get
Before you decide to sell, a few things will determine where in the range your phone lands:
- Condition grade. Small scratches might seem trivial, but they push a device from 'Excellent' to 'Good' in trade-in grading systems, which can mean a difference of £50 or more in your pocket.
- Battery health. Most reputable buyers require a minimum of 80% battery health. Below 75%, expect a 25–40% discount — or outright rejection.
- iCloud lock status. Sign out of your Apple ID and erase the device before handing it over. A device still linked to an account cannot be activated by a buyer and will be refused or heavily discounted.
- Storage capacity. Higher storage typically commands a modest premium, though the gap between 128GB and 256GB has narrowed in 2026.
How Tech4Cash buys your iPhone 15 or 16
Posting your phone to a recycler, waiting for an inspection, then discovering the quote has changed is exactly the sort of friction that causes people to miss the best selling window. Tech4Cash works differently.
We collect from your doorstep across the North East and Manchester — no trips to a post office, no queuing at a high street shop. We verify every device using PhoneCheck diagnostics, so there are no surprises about condition grades. And we pay instantly, so you are not waiting a week for bank transfer confirmation while the market moves against you.
If you are in the market for a replacement at the same time — whether that is an iPhone 16 or something else entirely — take a look at our refurbished iPhones. Every device comes with warranty and has been professionally checked. You can also browse our full refurbished stock if you are undecided on what to get next.
Ready to sell? Get a quote and book your doorstep collection at tech4cash.co.uk/sell-your-device. Given where the calendar sits, the best advice is straightforward: do it this week, not next month.
