Which Apple Watch should you buy? Which model, size, case material, colour and strap is best for your needs and budget? With dozens of combinations available, the choice can be overwhelming.

In our Apple Watch buying guide we explain all the options and help you decide which model is right for you and where to get the best price - although you should also check our roundup of the best Apple Watch deals.

Finally, bear in mind that now is not the best time to buy an Apple Watch. New models are generally released in September and we expect to hear about the Apple Watch Series 5 at Apple's 10 September press event.

Where can you buy an Apple Watch?

You can now pick up both the Watch Series 3 and Series 4 from an Apple Store (or order one online). Prices range from £279/$279 to almost £1,500/$1,500.

You can also buy the Apple Watch from third-party retailers, including John Lewis, Currys and Very. These sellers may still offer older models which Apple itself has stopped selling.

The current range

Apple has discontinued the original Apple Watch, Series 1 and Series 2, as well as the Edition line. You can currently choose from various versions of the Series 3 and Series 4.

There are aluminium (cheaper) or stainless steel (more expensive) versions of the Series 4, and numerous colour finishes and straps available for both the 3 and 4 - including Nike's sporty straps and fashion straps from Hermes. There are two screen sizes for each model, and you can also choose whether you want to pay extra for cellular connectivity, or if you're happy with GPS only.

Here's the Series 3 line-up, together with links to buy on the Apple Store:

Material Strap 38mm, GPS 42mm, GPS 38mm, cellular 42mm, cellular Buy link
Aluminium Sport Band £279/$279 £309/$309 £379/$379 £409/$409 Apple Store
Aluminium Nike Sport Band £279/$279 £309/$309 £379/$379 £409/$409 Apple Store

And here are the prices for the Series 4:

Material Strap 40mm, GPS 44mm, GPS 40mm, cellular 44mm, cellular Buy link
Aluminium Sport Band £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Aluminium Sport Loop £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Aluminium Nike Sport Band £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Aluminium Nike Sport Loop £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Steel Sport Band n/a n/a £699/$699 £749/$749 Apple Store
Steel Sport Loop n/a n/a £699/$699 £749/$749 Apple Store
Steel Milanese Loop n/a n/a £799/$799 £849/$849 Apple Store
Steel Hermes Leather Single n/a n/a £1,249/$1,249 £1,299/$1,299 Apple Store
Steel Hermes Leather Double n/a n/a £1,399/$1,399 n/a Apple Store
Steel Hermes Leather Rallye n/a n/a n/a £1,399/$1,399 Apple Store
Steel Hermes Leather Deployment Buckle n/a n/a n/a £1,499/$1,499 Apple Store

Best Apple Watch buying guide: Full range

With all these combinations to choose from, it's tricky to know where to start.

Series 3 vs Series 4

The first big decision is whether you want to pay substantially more for the new and redesigned Series 4 model, or if you want to save money and settle for the Series 3.

The 4 offers screens that are 30% larger than those of the Series 3, but it's slimmer too; overall the volume of the new models is lower. They also have a redesigned Digital Crown, which gives haptic 'click' feedback for more accurate scrolling, a new speaker (which is 50% louder), a repositioned microphone for better call quality and a new ceramic backplate which should improve cellular reception because it allows radio waves to penetrate.

The Series 4 has a new S4 processor - Apple says this is twice as fast as the Series 3's S3 - while its battery life is estimated to be the same as the Series 3 at 18 hours.

Thanks to new electric sensors the Series 4 can do ECG heart tests, and it's got a new function that detects when wearers have fallen and where appropriate calls the emergency services.

That's a whistle-stop tour of the main differences, but we compare the two models in more depth in our Apple Watch Series 4 vs Series 3 comparison article.

Best Apple Watch buying guide: Series 4 vs Series 3

Do I need cellular?

The next big choice is between a standard GPS watch and the more expensive cellular model, which uses an electronic SIM card to be able to make phone calls and get online independently of your iPhone. As well as the higher initial price, you'll have additional running costs for data usage and network fees.

Whether you opt for the regular or cellular (GPS or GPS + cellular to use Apple's terms) mostly depends on your likely usage. If you're always likely to have both your iPhone and Watch on you at the same time, you really won't see any benefit from the cellular connectivity, so it won't be worth the cost.

However, if you like the idea of being able to leave your phone at home and still take calls and check emails - when you're exercising, for example - then you could benefit from cellular.

Special editions

The Apple Watch Nike+ and Apple Watch Hermès have the same internals and specifications as the standard models, but distinct aesthetic appearances.

The Apple Watch Nike+, which is made from aluminium, is aimed at those who love running and are looking for a sport-oriented smartwatch.

The Hermès is made with stainless steel, with a unique strap and a Hermès stamp on the back. The various versions look lovely but start at more than £1,000. Note that these are only available with cellular.

Best Apple Watch buying guide: Hermes

Upgrading from the Series 2 or earlier

We've compared the Series 3 and 4, but if you've still got a Series 0 (ie the original model), 1 or 2 the new releases will look like a truly dramatic improvement.

Our experience suggests that at this point the original Apple Watch is basically obsolete: all the copies we own have slowed down drastically. To give an idea of the differences in speed between the various generations, we tried turning them all off and seeing how long they take to power on again:

Starting from the very first model, here are the highlights of what each model added to the formula:

  • 'Series 0' (2015): Officially just called Apple Watch, or 'first gen'. The original: where it all began.
  • Series 1 (2016): Essentially a rebadged version of the original. But it added a faster processor.
  • Series 2 (2016): A beloved upgrade. Increased battery life and screen brightness, and added GPS and better waterproofing. And a still faster processor.
  • Series 3 (2017): One big new (optional) feature: cellular connectivity. And an even faster processor.
  • Series 4 (2018): As mentioned above, brings a bigger screen, thinner body, more sophisticated heart sensors and fall detection. And the fastest processor yet.
  • Series 5 (expected in September 2019): Who knows?

As you'll appreciate, moving up more than one step at once means you get multiple sets of advantages.

Going from Series 2 to Series 4, for instance, means you'll be getting the option of cellular for the first time as well as the new design and ECG feature. Upgrading from Series 1 adds GPS and a better screen.

Should you buy the large or small size?

The Series 3 comes in two sizes of case: 38mm or 42mm. The Series 4 is 40mm or 44mm.

The general interpretation is that these are designed to suit an average woman and an average man's hand/wrist dimensions respectively, but you needn't feel bound by that: there are no other changes to the design of the watch other than size - no explicitly masculine/feminine decorative elements etc. (Also, a bloke can wear a woman's watch if he wants to. Don't let anyone tell you different!)

The measurements represent the (approximate) height of the watch face, in millimetres. That's a bit weird, because when categorising sizes of smart devices we usually refer to the size of the screen, measured diagonally from corner to corner, in inches. (The iPhone 5s is a '4in smartphone', for instance.) But Apple seems to have decided to do things differently this time.

Weight varies according to the material, size and whether or not cellular is included.

Best Apple Watch buying guide: Sizes

The size of a wearable is a crucial, critical factor, and because of this, we would recommend that you postpone the buying decision until you can be sure which size is right for you. That might mean buying in store rather than ordering online; if you can get to an Apple Store or a reasonably well-appointed reseller then they will have watches in stock that you can try on before buying.

Finally, bear in mind that the available configurations of material/colour/strap are slightly different depending on the size - so your choice in this category will slightly reduce your options in others. We strongly recommend that you prioritise size above other considerations, however. Don't be like the shoe shopper who goes one size too big because they're 90 percent off - the pain isn't worth it!

Which colour do you want?

The material used determines what colour you can find the Apple Watch in. In aluminium you'll find it in white, space grey, gold or rose gold. There's a plain stainless steel and a black stainless steel. The ceramic version comes in white or dark grey.

The colour, unlike the material, doesn't affect the price, so pick whichever version you like best. But your choices will depend on your choice of model and material.

The Series 3 only comes in aluminium, and this has to be either silver or Space Grey - not much choice there.

But the Series 4 offers lots more options. If you go for aluminium you can get this in silver, gold or Space Grey, while the stainless steel models come in plain, Space Black or (for the first time) gold.

Docks, stands and chargers

The Apple Watch comes with a small, basic charger, but you may wish to buy an additional dock that allows you to charge overnight while also displaying the time. For our picks, see our roundup of the best Apple Watch stands and chargers.