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(Pocket-lint) - Fitbit has an entire family of activity trackers, from the simple Fitbit Zip which counts steps, distance and calories burned, to the Fitbit Flex which adds active minutes and sleep monitoring.

The Fitbit Charge HR is the next step up in the range, expanding the Flex's functions by including continuous heart-rate tracking via a wrist-based sensor, an integrated display, and even a caller ID feature when paired with the associated smartphone app.

The Charge HR is bigger than the Flex and £40 more expensive, but is it worth the extra investment and does it set the bar for heart-rate monitoring fitness trackers?

Simple design

The Charge HR is fuss-free on the design front. It's a flexible wristband made from the same elastomer material found on many sportswatches, measuring 21mm wide, and that's about the long and short of it. Two sizes are available: small said to be suitable for 140-170mm wrists; and large for 160-200mm wrist diameters.

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The outside of the band is a textured surface, while the inside has a smooth, silky finish that feels comfortable against the skin. We didn't find it picked up as many marks as the Fitbit Flex, but this could be down to the dark colour.

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The Charge HR has a standard watch clasp, made from surgical-grade stainless steel, and the large model we had featured 10 holes for size variation. There is a Fitbit-branded plastic loop to thread the remaining strap through and a small pin inside the loop slots into the most appropriate hole. It's fiddly to thread the strap through with the pin in the way, but once in place, the Charge HR won't be leaving your wrist for love nor money.

The underside of the Charge HR's main body is where the heart-rate monitor sits. It's a small, slightly protruding rectangle that has a transparent square in the centre and two circular lights either side that continuously flash green. Some competitors don't flicker in the same fashion as this and, on occasion, we noticed the green glow when we were in bed, which we didn't appreciate.

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Above the heart-rate monitor is another rectangle with a small square and two pins that the accompanying charger plugs into. No separate cradle needs to be attached like with the Samsung Gear Fit, and there is no risk of losing the tracker itself during charging like the Fitbit Flex.

Battery life gave us between five and seven days on a full charge, which considering the active heart-rate monitoring is certainly better than some. However, when compared to the likes of the Withings Activité and Misfit Flash which last in terms of months, it's a different kettle of fish - neither of those offer a built-in heart-rate monitor.

On the Charge HR there's a plastic strip - a little thicker than that found on the Fitbit Flex - where the OLED display is housed. It's useful to view key data without the need to open the Fitbit app on your phone, like it is on the Withings Pulse.

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The display is operated by a small button on its left hand side of the Charge HR and each push will present a different feature's data, comprising the time, steps counted, heart rate, distance travelled, calories burned and floors climbed. What shows, including the clock display design, can be customised from within the app, but the order the features appear in can't. The app also enables one of the functions to be set to display when the main body is double-tapped, providing easy access to heart rate or number of steps, for example.

The Fitbit Charge HR may only have one piece of branding on it, which isn't even visible unless you turn your arm over, but it is clearly a Fitbit device. It carries the same design ethos as the Flex but it adds much more useful functionality.

Activity tracking plus caller ID

The Fitbit Charge HR does almost everything an activity tracker should do, while also real-time syncing to your smartphone via Bluetooth. Don't get too excited, though, as you won't get any messages, emails or Twitter notifications, nor will you be able to answer or reject calls - but you can see who is calling with the caller ID feature.

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The Charge HR will buzz excitedly when a call comes through and the name of the person calling will appear on the screen immediately. It's possible to turn off caller ID if you'd rather not be disturbed during a workout and while it might not be a game-changing feature, it's useful as we didn't miss any important calls.

For activity tracking, and compared to the Fitbit Flex, we found the Charge HR to be more accurate overall - and certainly less harsh than the Withings Activité; all of which we've worn simultaneously for the sake of science. We also counted the number of steps taken and compared them to what the Charge HR awarded us and each time it was either exactly to the step or a couple of steps out, and we mean literally just a couple.

The Charge HR can be set into exercise mode by holding down the button on the left of the display when you start and then again when you stop. The completed exercise can then be tagged in the app and there is everything from various running and rowing paces to elliptical and cycling options.

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Once an exercise is tracked, the app gives a run down of heart rate during exercise (as well as time in specific heart rate zones), the amount of calories burned and the impact on your day.

We tried exercise mode during several activities - including running, rowing and while on the elliptical machine - and the data collected was exactly the same as what each gym machine calculated, which is very impressive.

However, it's worth noting that once an exercise is logged, it can't be changed, so if the wrong rowing speed is selected for example, you are stuck with it unless you delete it, which gets rid of all the associated data and not just the exercise name.

The absence of GPS (global positioning) is the one area, and one area only, where the Charge HR is lacking. For the hardcore runner, no GPS will probably be a deal breaker, even if it is possible to use the MobileRun feature for pace, distance, splits and routes. Without using MobileRun, however, tagging an exercise as a run won't even guesstimate distance or pace like others do.

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When we didn't use exercise mode, we measured the distance of a 5km run by recording what our Charge HR said before and after. It calculated 4.64km so it was slightly off the mark, but the calories burned and active minutes appeared to be in line with what we expected according to the treadmill. Floors climbed is a little harder to measure the accuracy of, as storeys differ from place to place, but it was a good feature to have as it made us take the stairs and walk up the escalators rather than use the lift or stand still.

One other point worth mentioning is the Charge HR is only water-resistant, not waterproof. The 1 ATM rating means it's happy to accompany you in the shower but it doesn't appreciate baths or pools, making it of no use for swimming activities.

Great heart-rate monitoring

The continuous, automatic heart-rate monitoring is a great feature of the Charge HR. Being able to see heart rate in real-time by just double-tapping the main body of the device or pushing the side button a couple of times is brilliant, especially when running with target workout zones.

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It's certainly more comfortable to wear than a chest strap, plus compared to non-HR devices it helps achieve a better estimate of calories burned. A breakdown of the time spent in heart rate zones is found in an easy to understand format within the app too.

The Charge HR rarely failed to provide a heart rate reading during testing, and its positioning, automatic activation and constant read makes it considerably better than devices such as the Withings Pulse (where the heart rate function has to be launched and a finger placed on the monitor for 30 seconds, rarely providing an accurate result, if a result at all).

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The continuous monitoring also means it's easy to keep a track of your resting heart rate to see if your health and fitness is improving. As long as the Charge HR is worn all day and all night, it gives a good indication on what is going on when awake and asleep.

Basic sleep tracking

Sleep tracking is the area the Fitbit Charge HR falls down from its pedestal however. At least, compared to the smattering of other devices that offer such a feature. There is a noticeable improvement from previous Fitbit devices in that manually beginning a sleep log is no longer required, but the data it collects is far inferior to the likes of the Withings devices.

We found it logged sleep randomly at times and when editing a log, an error message causing sleep data to disappear completely wasn't uncommon, which is frustrating.

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In Fitbit's defence, sleep tracking isn't exactly a make or break feature for the Charge HR. It's all about heart rate. But considering how fantastic the Fitbit platform otherwise is, we would like to see the sleep tracking functionality expanded further as it currently feels more like an afterthought.

However, a silent alarm can be set on the Charge HR, however, which is not only easier to set than the equivalent on the Withings Activité, but also easier to turn off. A tap on the main body sets the Fitbit alarm to snooze for nine minutes, while a push of the display button turns it off.

Fantastic Fitbit platform

Ignoring sleep-tracking, the Fitbit platform is great and the app is brilliant. Syncing the Charge HR is instant as soon as the app is opened, unlike Withings where data can take a couple of minutes, and everything is displayed in an easy-to-understand format.

The Dashboard is where the party is at, showing everything from steps, heart rate, distance, calories burned, floors climbed and active minutes to logged exercises, weight management, sleep data, calories consumed, calories left and water consumed. It can be edited to only show certain features but we found we liked them all on show.

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The data from the Charge HR is instantly visible in real-time and there is a line underneath the calculation that displays progress, moving from red to green when you have achieved the goal you have set.

Step, distance, calories burned, active minutes and floors climbed goals can be changed in the Account section, as can the main goal you are hoping to achieve over a longer period of time. This is a great feature of Fitbit and one that isn't available on competitor platforms like Withings. It means if achieving 20km every day is your target, rather than 10,000 steps, then this can be set no problems. It's all about the goal most important to you.

Each section within the Dashboard also has more detailed information stored within, which is accessed by clicking on the respective feature. There is then a graph and a history of activity within that section and an even more detailed breakdown can be obtained by clicking on the graph. It's more hassle to access all the information than it is in the Withings platform but it also means the app looks cleaner and information is easier to read.

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Most settings are found within the Account section at the bottom of the app or by clicking on the Fitbit Charge HR itself at the top of the app under your name. The latter is where you can set a silent alarm, turn call notifications on or off, customise the display, choose a clock face, and alter heart-rate tracking between on, off and auto. Wrist settings, which feature appears with the tap gesture mentioned earlier and your main goal is also changed in this area.

In the Account section, along with changing specific goals, it's also possible to choose a custom heart rate zone, select a time zone, alter the sleep sensitivity, select what units the app presents and decide which day kicks of the start of the week.

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Linking Fitbit to partner apps such as MyFitnessPal means you get the most out of the platform, especially for calorie counters or weight monitors. Logging individual food is tedious to say the least but apps like MyFitnessPal make it a little easier with a barcode scanning feature. These two apps talk to one another seamlessly, too, which is helpful.

As with most platforms, Fitbit also has a section for challenges if you need extra motivation and there is a Friends feature so if anyone you know uses the platform, you can link up and compete against one another.


The Charge HR might be more functional in build than desirable like the Swiss Made Withings Activité, but as a fitness tracker Fitbit is far more detailed and excels in almost every department.

Automatic heart-rate monitoring is the Charge HR's most prominent feature and one that we will significantly miss after sending it back. Considering it can do this and still deliver near-week-long battery life is mighty impressive, even if having to recharge is a bit frustrating - but that's a small price to pay for real-time information and accessible data with or without the app running.

For gym goers not looking for a fully fledged GPS smartwatch, the Charge HR is definitely top of the pack. The exercise mode and heart-rate monitoring means it embraces indoor sessions, where its competitors seemingly ignore it, and while it isn't the best out there for dedicated runners or swimmers, it most definitely will fit into most people's lifestyles.

We weren't huge fans of how the Fitbit Flex looked and despite the Charge HR looking similar, it makes much better use of its footprint. More features, better accuracy, that at-a-glance OLED screen - for the £40 bump in price, it's clearly a no brainer.

Even though it's not gorgeous to look at, the Fitbit Charge HR certainly delivers a fitness-tracking experience a step ahead of the competition.

Writing by Britta O'Boyle. Originally published on 11 February 2015.