If you're thinking about upgrading to a new iPhone now that the iPhone 6 is just days away from being unveiled, you might want to consider trading in your old one. In this article, we're going to take a look at some of the options available for getting the most money for an older iPhone, whether it's an iPhone 5S, iPhone 5C, iPhone 5, iPhone 4S, iPhone 4 or an even older iPhone. We'll also offer some advice on how to prepare your iPhone for sale.

Wondering which phone to buy? Read: Should I buy iPhone 5s, 5c or wait for iPhone 6?

iPhone 6 preview | iPhone 6L preview

How to sell your iPhone: Prepare your iPhone for sale

Before you sell your iPhone, you'll need to make sure that you've wiped all of the data you've got stored on it, to prevent the person who buys it getting access to your sensitive data and details.

It's a fairly simple process, which we explain in our how to wipe your iPhone or iPad article.

Don't be tempted to sell your iPhone with your data intact because it has Flappy Bird on it, or something similar. When the game was removed from the iOS App Store this year, users began selling their iPhones for slightly more cash on eBay by advertising the fact that Flappy Bird was installed. The problem is that the game is connected to your Apple account, and therefore you're selling them some of your personal data too.

You'll also want to gather together all of the cables, accessories and packaging you've got for the iPhone. Make sure you specify what the iPhone comes with in terms of cables and packaging, particularly if you're selling on eBay.

How to sell your iPhone: How much can I get for my old iPhone?

Apple itself offers a fair deal through its iPhone trade-in programme, which could get you up to £220 to put towards a new iPhone.

The iPhone Reuse and Recycling Programme allows customers to trade-in their old iPhone – from the original iPhone to the iPhone 5 – by visiting an Apple Retail Store with their old iPhone or visiting Apple's Reuse and Recycling webpage.

If you decide to take your old iPhone into an Apple Retail Store, Apple's staff will look over it and give a trade-in price estimate. This price is based on the condition of the hardware and the model of iPhone. Customers can then get that value subtracted from the price of a new iPhone or other Apple product should they decide to trade-in.

If you choose to go through the trade-in process online, you'll need to visit Apple's Reuse and Recycling webpage, answer a set of questions to help Apple come up with the estimated value of the device, then send your iPhone to Dataserv for evaluation. Once Dataserv (Apple's recycling partner) has checked your device and determined the accurate trade-in value, you'll get that money deposited into your bank account.

See also: iPhone buying advice

Do you have an older iPhone? Find out how to unlock your iPhone 4 here.

Here at Macworld UK, we also offer a trade-in service in co-operation with mResell, which let's you enter the serial number of any Apple product and get a quick quote to find out how much you can get from it through the service. You can find out how much you'll get for your iPhone, whichever model you've got (Apple doesn't offer a trade-in programme for the iPhone 5s or iPhone 5c just yet), by clicking here.

You can get a reasonable amount of money from Apple, third-party buy-back companies in exchange for your old iPhone, particularly if you've kept that iPhone in good condition. You can also sell it on eBay, Gumtree or similar. Here, we talk you through the best places to get money for your iPhone, and let you know how much to expect to recieve.

How much is my iPhone worth? Original iPhone value

If you own the original iPhone, you probably won't be too pleased with Apple's valuation. We found that the maximum Dataserv estimate for the first iPhone is £5.00.

You'll probably get more for your original iPhone by selling it on eBay. In fact, one Australian Ebay seller has been attempting to sell a brand new, sealed first generation iPhone for £55,513, which is a bit extreme. A more realistic expectation is £20, though if it's brand new or comes in the box you might find that it sells for £100 or more. Don't forget, though, that you'll need to pay eBay and PayPal fees on top of postage if you sell through the online auction site.

It's worth investigating Gumtree to avoid such charges, though you won't get the support you get from eBay and PayPal if you use that service.

How much is my iPhone 3G worth? iPhone 3G value

Similarly, those with an iPhone 3G might want to think about an alternative way of getting money from their old device. Apple offers just £5.00 through its Reuse and Recycling programme. This is significantly more than Carphone Warehouse's trade-in offering of £2.70, but on eBay, you could get £20 to £30 for it.

How much is my iPhone 3GS worth? iPhone 3GS value

If your iPhone 3GS is in tiptop condition, you could get up to £15 for it through Apple's Reuse and Recycling Programme. That's still not as much as you could get from eBay, though. A 32GB iPhone 3GS could get you around £50 through the online auction site.

Carphone Warehouse offers just £9 for a 32GB iPhone 3GS.

How much is my iPhone 4 worth? iPhone 4 value

Onto the iPhone 4 now, and for a 32GB model in good condition, you're looking at a sum of £90 from Apple's Reuse and Recycling programme. That's much more than offerings from Carphone Warehouse (£45) and other third-party trade-in services from companies such as O2 (£82) and Envirofone (£75).

It's also not dissimilar to the kind of money you can expect to get for your iPhone 4 if you decide to sell it on eBay. Don't expect to get much more than £100 for a 32GB good condition iPhone 4 on eBay.

It's therefore worth checking out Cex if you want to sell your iPhone 4. It claims to offer up to £108 for a 16GB model, or a voucher valued up to £153.

How much is my iPhone 4S worth? iPhone 4S value

If you've got an iPhone 4s, the maximum amount that Apple will give you is £130. That's for a 64GB iPhone 4s that has no liquid damage, no display damage and no other damage.

If you've got some scratches on the iPhone, you're looking at a maximum of £97.50, and as soon as you add further damage you can expect an estimate of £60 or less.

The good news is that even a 16GB model of the iPhone 4S can get you £110 through the Reuse and Recycling programme.

Apple's offerings here are more generous than third-party services we checked, including Envirofone (£110 for a 64GB model) and Carphone Warehouse, which only offers £85 for a working 64GB iPhone 4S. Cex, on the other hand, offers up to £131 for the iPhone 4S.

We'd suggest thinking carefully about Apple's offer here. We've seen used iPhone 4S models go for just £100 on eBay, and not many appear to sell for much more than £150.

How much is my iPhone 5 worth? iPhone 5 value

Here's the biggy. Apple is offering up to £220 for a good condition iPhone 5 through its Reuse and Recycling Programme, which we think is rather generous, and either matches or beats many of the iPhone 5 models we've seen selling on eBay.

O2 offers £180 for a 64GB iPhone 5, while Envirofone offers £175 and Mazuma Mobile offers a measly £145, so Apple beats those third-party trade-in services too.

Cex offers up to £237 for the iPhone 5, which is quite generous!

If you're worried about scratches on the back of your iPhone 5, you might be looking at a price of £165 or less, though. However, even if you've got a 64GB iPhone 5 with a completely smashed display, Apple will still give you £143.

For a 16GB iPhone 5 in good condition, you're looking at a value of £190 from Apple, while a 32GB model is worth £210 to the company.

Overall, Apple's Reuse and Recycling Programme is certainly food for thought. We're not sure how long Apple will offer this much cash in exchange for your iPhone so you might want to think fast. Plus, it's unlikely that Apple will continue offering this much for your old iPhone when the new iPhone 6 becomes available to buy on 19 September, though we expect you'll still get a decent sum as encouragement to upgrade to the latest model.

How much is my iPhone 5s worth? iPhone 5s value

You can't trade-in your iPhone 5s with Apple (yet), but most of the third-party buy-back companies and trade-in programmes we've mentioned will buy your iPhone 5s from you. Cex offers up to £356 for a 64GB iPhone 5S, or a voucher with the value of up to £430.

eBay is an appealing option, though, as you could get get more than £400 for a good condition iPhone 5s there.

How much is my iPhone 5c worth? iPhone 5c value

Similarly, Apple doesn't offer a trade-in for the iPhone 5c, but you can sell it on eBay for £200 - £300 depending on the condition.

You can also get money for it from Cex, which offers up to £237 according to its website, which is the best we've been able to find.

Read more about the iPhone 6 in our iPhone 6 zone, including our iPhone 6 preview. We also have the 8 features we think the iPhone really needs: Eight things I want to see in the iPhone 6, essential features for the new iPhone 6 and the 7 most ridiculous iPhone 6 rumours. Why not take a look.