Left to right: Fitbit Charge HR, Fitbit Blaze and Fitbit Surge

Fitbit has long been the market leader in wearable fitness trackers. If you’re looking to buy a device that will automatically log and analyse your daily activity or training, there’s every chance a Fitbit is on your shortlist.

But even when you’ve decided you want a Fitbit tracker, which one should you choose? There’s no need to pay for features you don’t need, but equally you don’t want to miss out on features you’d find useful. We’re here to help by breaking down the key differences between models.

Any Fitbit will count your steps and estimate the distance you’ve covered and the calories you’ve burned, as well as tracking your sleep and gently waking you in the morning by vibrating on your wrist. Each tracker will also connect to your smartphone via Bluetooth or wirelessly sync to a computer using the USB dongle included in the box. This is good news because the Fitbit app and web portal is the best around. Remember, it’s not just about the device on your arm!

Fitbit Charge HR (£119.99 RRP) – a step up for the active user

The upgrades Heart-rate monitor and altimeter

The Fitbit Charge HR takes things up a notch by tracking beyond everyday activities. The standout feature is an integrated optical heart-rate monitor that continually measures your beats per minute.

The Charge HR logs your resting heart rate, a good indicator of general cardiovascular fitness, while also giving you continuous live heart-rate data. In exercise mode, it’s also easy to see how hard you’re working and in which cardio zone.

As well monitoring your heart rate, the Charge HR counts the flights of stairs you climb each day using a built-in altimeter – a great feature that encourages you to dump the lift for good.

The OLED display on the Charge HR displays your stats and works with your smartphone to deliver notifications.

The Charge HR will appeal to the more serious user who welcomes the heart-rate monitor and altimeter.

Fitbit Blaze (£159.99 RRP) – for the fitness-obsessed smartwatch lover

The upgrades Full-colour touchscreen, smartwatch features, connects to your smartphone’s GPS and includes guided bodyweight workouts

Smartwatches are becoming more and more fashionable, and the Fitbit Blaze fits right in without sacrificing its fitness tracking roots. The Blaze is a great-looking device, with a large, easy-to-read colour touchscreen. It can also be removed from its strap, opening the door to a plethora of options – the standard strap is great for the gym, leather straps enhance the aesthetics, while the latest gun metal Blaze is a real looker.

The great thing about the Blaze is that you can wear it like a normal watch without feeling self-conscious. You can choose from a variety of watch-face designs, and the display comes to life as you lift your wrist to view the watch.

The Blaze has an optical heart-rate monitor that constantly measures and logs your beats per minute. Because it’s designed to be worn all day, the Blaze also tracks your resting heart rate and recovery time after workouts. It also tracks steps, distance, calories and flights of stairs climbed. Carry your phone with you and the Blaze can use the phone’s GPS to accurately track your distance, speed, pace and route.

The Blaze has other fitness credentials, too. The FitStar feature takes you through a series of bodyweight workouts, with step-by-step instructions displayed on the screen.

The Blaze doesn’t just look like a smartwatch, it acts like one too, relaying text messages and calendar alerts from your phone, as well as displaying caller ID. You can also use it to control the music you’re listening to on your phone. And with a battery life of five days, you won’t have to charge it every night like most smartwatches.

Fitbit Surge (£199.99 RRP) – for the serious athlete that loves data

The upgrades Built-in GPS

The Fitbit Surge is so much more than a tracker – it’s a full-blown training partner for serious fitness freaks. Yes, it will track every step you take, how far you’ve walked, how many calories you’ve burned and how many flights of stairs you’ve climbed, but that’s just the tip of the iceberg.

While the Blaze uses your phone’s GPS, the Surge has its own built-in GPS receiver. That means that every time you run, the Surge accurately logs your speed, distance, pace and elevation, while logging your exact route.

You’re not limited to just running with the Surge, as the GPS receiver does an equally good job tracking your speed, distance and pace whatever you’re doing – cycling, rowing or even rollerblading.

There’s also an integral optical heart-rate sensor to track your heart rate while training, as well as monitoring your resting pulse. It also ensures your calorie-burn data is as accurate as possible.

The Surge can be a smartwatch, too, relaying your text messages, caller ID and calendar notifications.

The Surge lasts around five days following a full charge, but real-world battery life depends on how often you use the GPS – if you go running every day, you’ll probably need to charge the Surge every three days or so.

According to Fitbit, the Surge is a “fitness super watch” providing all the fitness tracking metrics you could ever want, along with full GPS tracking functionality. If you train hard and want to keep track of every step run, every kilometre cycled and every metre climbed, the Surge is the Fitbit for you.

RECOMMENDED: Fitbit Surge Review

If you just want to track your everyday activities, check out the Fitbit Flex (£79.99 RRP) or Fitbit Alta (£99.99 RRP). They are the perfect way to motivate you to do more every day.