Now's the best time to trade in or sell your iPhone. Why? It's because prices are currently the highest they'll be before they decline very soon - around 25 percent better. 

MusicMagpie has reported that iPhone X trade-ins are up by 291% following Apple announcement on Tuesday. The site has also revealed that iPhone 8 and 8 Plus trade-ins are up 214% and 223% respectively.

That's because today sees the launch of the iPhone XS and two other iPhone variants thought to be the iPhone XS Plus and a cheaper version of the iPhone X with a slightly larger 6.1-inch screen and aluminium body (maybe called the iPhone XC). 

You don't have long before prices fall

CompareMyMobile reckons you have four days grace following a new iPhone launch to sell or upgrade in order to get the best value so that means prices will start to go down tomorrow probably.

The trade-in site says that in the week leading up to last year’s Apple Event and in the four days following the event, the value of iPhone handsets didn't really depreciate but that subsequently prices significantly declined. 

Most trade-in sites will guarantee the offer they give you for a week or two - CompareMyMobile, for example, will guarantee your iPhone trade-in price for 14 days.

What can you expect to get for your old iPhone?  

According to Compare and Recycle, iPhone 6 owners stand to gain the most. For the past three months, the 128GB model has enjoyed the biggest spike of £50 in recycling price followed by the 64GB with a price increase of £30 to date.

MusicMagpie's figures for last year's phone are quite favourable. If you trade in an iPhone X 256GB you can expect to gain £680 now. So if you go and buy this year's model it will be a more palatable £319 upgrade providing the iPhone XS retains last year's £999 price point.

However, Compare and Recycle believe that depreciation is lower on models with lower capacities if you're going to sell and upgrade year after year but interestingly higher capacity models are the best bet if you're going to keep your phone for a long time. 

MusicMagpie reckons the iPhone X has held its value higher than any other Apple model released in recent years, a trend that the site has seen more often with Apple’s higher-end models - an average of 68 percent of retained value in a year, in comparison to older devices such as the iPhone 7 and 6 which only managed to hold onto an average of 40 percent of value after a year.

The 64GB iPhone 6 Plus is now earning an average price of £210 says Compare and Recycle and a high capacity iPhone SE, which originally came out as long ago as March 2016, could reach £200 before the launch.

The iPhone 8 Plus 256 GB on the other hand, will earn you £549 when traded-in according to MusicMagpie. That means the iPhone 8 Plus has held onto 57% of its value in 12 months.

We've known for some time that iPhones tend to retain value better than other handsets. According to MusicMagpie, these figures contrast with the Samsung Galaxy S9, with the S9+ being particularly hard hit; losing nearly 50 percent of its value since launch while handsets from OnePlus and Google have lost an average of 80-85%.

The best thing you can do is confirm a trade-in price before the announcement to ensure a high price on trade in - although you're too late for that this time. 

What about Apple GiveBack?

Apple also offers its own programme, called Apple GiveBack which enables you to trade in various devices (they don't have to be Apple-made) in exchange for an Apple Store Gift Card. However, the prices quoted often don't give you as good a deal as you can find elsewhere. Rival recyclers are quick to jump on this, of course, with SellMyMobile going so far this year as to issue a price comparison chart of the contrasting prices offered for the iPhone X. It reckons you can get up to 37 percent more recycling with other companies compared to Apple GiveBack. As always, our advice is to shop around.