Fitbit currently sells four activity tracker wristbands – the Fitbit Flex, Fitbit Charge, Fitbit Charge HR, and Fitbit Surge – and two belt-clip or carry-on activity trackers: Fitbit Zip and Fitbit One. Which is best for you? Which one should you get?

The Fitbit Surge is set to go on sale as part of Amazon's HUGE Amazon Prime Day sale at 7:30pm today (15 July). You can find out more in our Amazon Prime Day deals live blog.

Choosing the best Fitbit for you will come down to features and price, but you should also consider size, battery life and of course looks. Which Fitbit is best depends on what you want and how much you’re willing to pay. We explain all in the buying guide to the Fitbit activity trackers. Fitbit trackers compared and features in detail.

For more detailed reviews of each Fitbit activity tracker go to our dedicated review pages, listed below. This round-up feature looks at each Fitbit tracker and compares them with each other in terms of features, functions, design, battery life, display, specs, colours, box contents,  and of course price.

More: Fitbit Charge review     Fitbit One review     Fitbit Zip review     Fitbit Flex review     Fitbit Charge HR review     Fitbit Surge review

There are other activity trackers, of course. Here's our round up of the best activity trackers currently available. Also: Fitbit vs Apple watch

Which Fitbit

Which Fitbit: price

Let's start with a key factor: cost. None of the Fitbits are pocket change but none are horrendously over-priced either. You'll find cheaper variations online and in supermarkets but with Fitbit you know you are going for a quality platform. And if you start walking more you can make the money back quite quickly by not taking the bus, tube or train. I saved £100 in around two months, and got fitter into the bargain.

The Fitbit Flex currently costs £79.99, £20 cheaper than the Fitbit Charge (£99.99). The Fitbit Charge HR costs £119, and Fitbit Surge £199.

If price is important you may be better off trying the clip-on Fitbit Zip or Fitbit One instead. The £79.99 One costs the same as the Flex, but, as we’ll see, offers more features. You can also find it on sale online for a tenner cheaper at £69.99.

The Fitbit Zip has an RRP of £49.99 but is available online for around £40.

We think that the £20 difference between the Charge and the Charge HR might be worth paying for the extra heart-rate-monitoring functionality. But if you're just interested in everyday exercise the Fitbit Charge will suffice, and is an excellent tracker. We also prefer the Charge HR's watch-buckle strap, which feels more secure.

Which Fitbit: features

Fitbit trackers compared. The cheaper clip-on and wristband Fitbits (Zip and Flex) don’t offer all the features found on the One and Charge, Charge HR and Surge.

All Fitbits have a MEMS 3-axis accelerometer that measures motion patterns to determine your calories burned, distance traveled, and steps taken. All but the Zip also monitor sleep quality.

The One, Flex, Charge, Charge HR and Surge also contain a vibration motor, which allows it to vibrate when alarms are set to go off.

The One, Charge, Charge HR and Surge boast an altimeter that measures stairs climbed.

The Surge boasts eight sensors –3-axis accelerometers, gyroscope, compass, ambient light sensor, GPS and heart rate. It tracks seven days of detailed motion data – minute by minute, and daily totals for past 30 days. The Surge stores heart rate data at 1 second intervals during exercise tracking and at 5-second intervals all other times. The Sample rate for GPS is 1Hz.

The Charge HR and Surge monitor your heart rate, and without having to lash sensors to your chest like some HR trackers demand. It's all done on the wrist. They use Fitbit's PurePulse heart rate technology that gives continuous, automatic, wrist-based heart rate, plus simplified heart-rate zones.

The Charge, Charge HR and Surge will all show Caller ID when linked to a smartphone. The Surge will also display text notifications on its display, and allow you to control your music from the touchscreen display. We found call notifications super useful.You can rely on the wriststrap buzz more than your phone's vibration, and even see who's calling right their on your wrist, which is more polite than and easier than pulling our your phone when chatting to someone else.

The top two Fitbit wristbands feature multi-sport exercise tracking to easily record workouts and see real-time exercise stats and summaries. Fitbit's website is a bit vague on the Charge HR's multi-sports tracking, and we are awaiting clarification on this. If losing weight is one of your aims then you should consider the Fitbit Aria, digital scales that wirelessly sync with your account and measure your weight, body fat percentage and BMI.

On top of all this the super-fitness-stats Fitbit Surge features GPS tracking, without the need for a smartphone to be linked. Users can see distance, pace and elevation climbed, and review routes and split times. This beats the Apple Watch, which relies on the GPS in your iPhone.

The charts below shows all Fitbit features by device model, plus prices. Click on the image to expand on desktop.

Fitbits compared activity trackers features UK prices

Here's what Fitbit tels you about each. Click for a larger view on desktop.

Fitbit trackers compared store UK prices

Here's how Fitbit list each of the trackers' special features, starting with the Flex:

Fitbit Flex features

Now, the Charge features:

Fitbit Charge features list

Next, the Charge HR features:

Fitbit Charge HR features list

And finally the Surge features:

Fitbit Surge features list

Top 10 tips for hitting your Fitbit step goals

Fitbit improvements: skin allergies and better clasp

Fitbit was bitten hard when it had to withdraw and recall its Fitbit Force wristband when some owners reported developing a skin rash as a result of metal allergies. The company now says that it has employed scientific experts Dr Peter Schalock, an Assistant Professor of Dermatology at Harvard Medical School, and Dr Patricia Norris, Assistant Professor of Dermatology at Oregon Health & Science University, to make every effort to reduce the chances of Fitbit users having reactions from parts of their wristbands.

Fitbit still warns that “if you have eczema, allergies, or asthma you may be more likely to experience a skin irritation or allergy from a wearable device.”

It also advices that “if you sweat for more than two hours while wearing your Fitbit band, be sure to wash your band and your wrist using the directions above to avoid skin irritation.”

Each new wristband is made of a flexible, durable elastomer material similar to that used in many sports watches.

Another problem that beset Force owners was the wristband's weak clasp, which lead to many – me among them – losing their treasured tracker. Now take a look at the back of the Charge HR, and you'll see a surgical-grade stainless steel buckle that's much more like a standard watch. The new buckle is found on the Charge HR and Surge, but not the Flex or Charge. Fitbit has improved the Charge's strap, but it lacks its betters' buckle.

The buckle isn't uncomfortable when worn in bed, and we think it might be wirth the extra £20 all on its own.

Charge HR Fitbit back clasp photo

Which Fitbit: display

The Zip display has five modes: Steps; Distance; Calories burned; Fitbit Smiley (highlights your recent activity level); and Clock.

Fitbit Zip display modes

The One’s display has six modes: Steps; Distance; Calories burned; Floors climbed; Flower (grows and shrinks based on your recent activity); and Clock.

Fitbit One display modes

The Flex’s display is the most minimal, consisting of a series of flashing dots that show you how your day is stacking up against your goals. Each light represents 20 percent of your goal. You just tap the display twice to see your progress against your daily goal. This is very easy to get used to but isn’t as informative as the other Fitbits. Of course you can see all your stats via the Fitbit iPhone or Android smartphone app.

Fitbit Flex display modes

The Charge's OLED display (below) shows Time; Steps; Distance; Calories burned; Floors climbed; Very active minutes; Caller ID; and Alarm.

Fitbit Force display modes

The Charge HR's OLED display is much like the Charge but includes extra features. It shows Heart Rate; Exercise Tracking; Time; Steps; Distance; Calories burned; Floors climbed; Very active minutes; Caller ID; and Alarm.

Fitbit Charge HR display screens tracks

The Surge's larger display (below) shows even more data to fitness and sports nuts. Its display is a touch screen monochrome LCD with backlight (for low light visibility).

Fitbit Surge screens

Which Fitbit: measurements and specs

While the Fitbit One and Zip are small and can clip onto clothing or sit in your pocket they’re in some ways less flexible than the wristbands.

You’re less prone to forget a fitness wristband than you are a tiny clip-on gadget. The short-lived Fitbit Force had a tendency to unclip with its loose clasp, and I know several people – including myself – who have lost their Fitbit wristband when it's been knocked and then silenty falls to the floor. Fitbit has made the clasps on its new Charge, Charge HR and Surge wristbands much firmer.

The Flex is thinner and slightly lighter than the Charge. The Flex is 13.99mm wide, compared to the Charge's 21.1mm girth – the old Force was 19.2mm wide. As the Charge/HR/Surge also include a watch function they might actually save you wrist space as you can ditch your watch.

The Zip is the smallest of the Fitbits – it’s shorter than the One but podgier.

When you buy a Flex you get both a large (161-209mm) and small (140-176mm) wristband, but with the Force you need to specify whether you want Small, Large or X-Large, as the tracker itself is built into the band. You can check with Fitbit’s online wristband sizing tool.

Fitbit Zip measurements specs size

Fitbit Zip size and weight: H: 48mm; W: 19.3mm; D: 9.65mm; Weight: 8g.

Fitbit One measurements specs size

Fitbit One size and weight: H: 35.5mm; W: 28mm; D: 9.65mm; Weight: 8g.

Fitbit Flex measurements specs size

Fitbit Flex size and weight: W: 13.99mm; Weight: 29g.

 Fitbit Force measurements specs size

Fitbit Force (discontinued) size and weight: W: 19.2mm; Weight: 30g.

Fitbit Charge wristband tracker

Fitbit Charge size guide wristband

Fitbit Charge size and weight: W: 21.1mm; Weight: 24g.

Fitbit Charge HR wristband tracker

Fitbit Charge HR sizes

Fitbit Charge HR size and weight: W: 21.1mm; Weight: 26g.

Fitbit Surge activity tracker wristband

Fitbit Surge sizes

Fitbit Surge size and weight: W: 34mm; Weight: 51g.

Which Fitbit: battery life

Remembering to keep your Fitbit charges is important if you wish to keep your activity tracked. The longer the battery life in between charges the better, then.

The Zip is easily the best for battery life but you will need to buy a new battery two or three times a year. The 3V coin (CR 2025) battery is cheap, though – you can buy a pack of five for under £2.50. The other Fitbits feature rechargeable batteries.

The Fitbit Flex lasts the shortest time between charges. Remember that accessing the display on any of the Fitbits will drain the battery faster.

Fitbit One battery life: 5-7 days

Fitbit Zip battery life: 4-6 months

Fitbit Flex battery life: 5 days

Fitbit Force battery life: 7-10 days (Discontinued)

Fitbit Charge battery life: 7-10 days

Fitbit Charge HR battery life: 5+ days

Fitbit Surge battery life: Up to 5 days

Which Fitbit: water resistance

Sadly none of the Fitbit activity trackers can monitor your swimming. But you can at least wear your Flex in the shower, unlike the other Fitbits that are less happy getting wet.

I did wear my Flex while swimming and after a few months the rubber wristband did begin to perish a little, and my wife claims that it started to smell – so best taken off for long periods of liquid submersion.

The Fitbit One, Zip and Force are splash proof, but should not be submerged more than one metre.

The Flex, Charge and Charge HR are water resistant to 1 ATM (Atmosphere), so theoretically can be submerged up to 10 metres (33ft). However, watch specialists advice that a device with this resistance level is protected against accidental exposure to water; for example, splashes, perspiration or accidental immersion; and state that it should not be exposed to any water pressure.

The Fitbit Surge is water resistant to 5 ATM, which means it is wearable around household sinks, while playing sports and while swimming in shallow water. Experts recommend that you don't wear it while bathing, snorkeling or scuba diving. For more on water resistance ATM ratings see this guide for watch owners.

Which Fitbit: colours

The Fitbit One is available in either Burgundy or Black.

Fitbit One model colours

The Fitbit Zip is more colourful, available in either Blue, Magenta, White, Charcoal or Lime.

Fitbit Zip model colours

The Flex wristband is available in ten colours: Black, Slate, Tangerine, Teal, Navy, Violet, Blue, Lime, Pink and Red. You can buy extra bands (without the tracker) for £12.99.

Fitbit Flex Colours UK

The Force (discontinued) was sold in just Black and Slate. Slate is a greyish blue.

Fitbit Force model colours

The Fitbit Charge is available in Black, Slate, Blue and Burgundy.

Fitbit Charge Colours

The Fitbit Charge is available in Black, Slate, Blue and Burgundy. At the time of writing only the Black was available on the Fitbit Store.

Fitbit Charge HR four colours

The Fitbit Surge is available in three colours: Black, Blue and tangerine.

Fitbit Surge colours

Which Fitbit: what you get in the box

The Fitbit Zip ships with tracker, silicone and metal clip, wireless sync dongle, replaceable battery and battery door tool.

Fitbit Zip box contents

The Fitbit One comes with tracker, silicone and metal clip, wireless sync dongle, charging cord and sleep wristband.

Fitbit One box contents

The Fitbit Flex includes tracker within wristband (small and large), wireless sync dongle, and charging cable.

Fitbit Flex box contents

The Fitbit Force (discontinued) came with tracker within wristband (either small or large), wireless sync dongle, and charging cable.

Fitbit Force box contents

The Fitbit Charge and Charge HR come with tracker within wristband (either small, large or x-large), wireless sync dongle, and charging cable. For some unknown reason the Charge and Charge HR have different charging cables.

Fitbit Charge accessories

All work with the Fitbit desktop dashboard and iPhone and Android apps.

Fitbit activity stats and sofware

Which Fitbit is best for you?

It’s possible to look at the Fitbit activity trackers in two groups. (We are ignoring the Fitbit Ultra and Fitbit Force as they are no longer available.)

The clip-on One and Charge, Charge HR and Surge wristbands boast the most features, including Floors Climbed via the altimeter. They also show more right there on their displays. The Charge, Charge HR and Surge also show Call Notifications from your phone, including Caller ID.

The Zip and Flex are cheaper but don’t include the altimeter so climbing lots of stairs will count only as Steps and not as the harder climb. Of course floors climbed counts as Steps on the other trackers, too.

The Zip doesn’t vibrate when you reach your targets. And it doesn’t monitor your sleep efficiency.

The Zip is the cheapest Fitbit, and if you can live without the altimeter and sleep tracking then this is a great entry point. Sleep tracking is fun but not at the top of most people's fitness lists, but the buzz is a great way to know you’ve reached your key target. Is that worth an extra £30 for the One or Flex? That’s really up to you.

Fitbit Flex vs Charge vs Charge HR vs Surge: When it comes to choosing between the four Fitbit wristbands we love the Flex’s minimalism but think the Charge's better display and altimeter make it worth the extra £20, depending on where you buy it.

The Flex is a great activity tracker in its own right, and syncs well with your smartphone and computer. It's also available in more colours.

If you're  a keen gym goer or jogger the heart-rate-monitoring Charge HR is just £20 more than the Fitbit Charge. You also get the better strap (buckle) with the HR, and even if you're not a fitness nut the heart-rate monitor is a fun addition, so there's another £20 that could be worth investing. From someone who has lost a wristband I'd go with the most secure strap, and that means either the Charge HR or Surge.

The Surge has so much more than the other Fitbits and costs quite a bit more, so is maybe an unfair comparison. It's for real gym fanatics and at least the semi-serious runner. Or you can wear one, and pretend to be a performance fitness nut, and just use it to count your steps and tell you the time.

There's a Fitbit trackers for everyone. If you're unsure you can always later sell up and upgrade to a higher-spec Fitbit tracker. Getting fitter now is the main thing, so get started soon.