Which hardware features do you actually need on a fitness tracker?

Feature creep is a common problem in the technology industry. Companies want to offer more bullet points than their competitors, and in many cases this actually results in superior products. But it also keeps prices artificially high and sometimes makes devices unnecessarily complicated – consider the sheer number of options that were once crammed into flagship Samsung phones. The more complicated something is, the more likely it is that it will break, be harder to use, or cost a fortune.

This is increasingly the case with fitness trackers, so newbies may have no idea what technologies are actually doing, let alone which ones they need. Before shopping, it is a good idea to make a list of mandatory hardware features versus those that are just nice to have.

Must-have features for every fitness tracker

The most critical element is a heart rate (HR) sensor. Motion sensors give a general sense of fitness, but tend to favor cardio workouts like running and walking and only provide the roughest possible estimate of calorie consumption. Comparing resting and active heart rates can help people understand their overall fitness level and heart health. On devices like the Apple Watch, HR can even provide warning signals for atrial fibrillation, i.e. irregular heart rhythm.

The maximum accuracy of the heart rate at the consumer level can be achieved with an optical bracelet or an EKG-based chest strap. However, you can easily skip these if you want smartwatch features. In fact, there are some very reliable options for the wrist from manufacturers like Apple, Garmin, Polar, Suunto, and others.

Next, a sturdy or durable design is on the priority list. As an absolute minimum, a device should be IPX4 waterproof, meaning it can withstand sweat and light rain. More realistically, you should ask for at least an IP68 rating to protect against dust, submersion, or showering. You should have a 5ATM rating (or higher) if you want to wear a tracker while swimming, which you can find on most fitness wearables these days. While many wearables have water resistance ratings, this hasn’t always been the case. Keep this in mind when purchasing an older model.

See also: Waterproof Technology: Everything You Need to Know About IP and ATM Ratings

The battery life should be considered according to personal needs. For all-purpose smartwatches, 24 hours is typical and sufficient – you just have to charge it every day. If you want to try sleep tracking, it’s better to find something with at least 48 hours, preferably closer to five days. If you do frequent marathons or weeklong camping trips, it’s time to look for brands like Garmin or Coros that offer devices that offer weeks of performance. Some Garmin watches even have a solar charge, which does not allow infinite life, but can extend it.

Essentials for selected people

Nowadays, GPS location tracking is almost non-negotiable for users while running, hiking, or biking. Depending on your home area, you may also want support for the Galileo (Europe) and GLONASS (Russian) satellite networks. Note that if you plan on navigating without a phone, you’ll need a tracker with offline maps, which can mean more expensive devices from brands like Garmin and Suunto.

Related: How do GPS, GLONASS and BeiDou work in wearables?

Cellular communications can come in handy, but it’s less important than you might think. If you’re out and about with your tracker, chances are you have your phone too. If you don’t, then you’re probably on a run or a ride, and offline caching of music, podcasts, and / or workout data may be enough. Cellular is most useful for people who can’t bring their phone but need to stay in constant touch or have live navigation data connected. If communication is critical, you’ll also want phone notification support and possibly the ability to reply to messages directly.

A pulse oximeter (also known as a SpO2 or blood oxygen sensor) is usually just a plus, despite the recent hype in the industry. The technology measures oxygen saturation in the blood, which can be useful for athletes to measure performance using a statistic called VO2 max. Some companies, namely Fitbit and Withings, are turning to sleep apnea detection. Otherwise, an oximeter is only good for certain medical concerns – when saturation regularly drops below 90%, it’s time to see a doctor.

A compass, altimeter, and / or barometer are all more complete and should generally be searched for for accurate altitude and movement information. They’re especially valuable when you are hiking in the wild and need to know which direction to go before a storm hits. However, they can be left out if you are interested in stationary activities like weight lifting or yoga.

Something that is hyped on some newer wrist trackers is the EKG (electrocardiography). Chest straps use an EKG to measure general heart rate activity. In practice, however, wrist-based implementations are only useful for capturing extreme heart rate variability and / or atrial fibrillation (AFib) that requires you to sit still with your finger on a knot for several seconds. Don’t worry about the wrist EKG unless you suspect a heart problem.

Some trackers offer on-device training coaching, which is an admirable idea, but not for everyone. For starters, any coaching capable tracker that requires a display, adequate processing power, and memory will still have limited animation capabilities and a small screen size. If you’re just starting out, it is preferable to work with a personal trainer to create a shape or combine a structured training plan with video tutorials. Veterans already know what they’re doing and have bigger goals – Fitbit isn’t going to teach people how to do a 400 pound squat. Integrated coaching works best in the middle ground, where people have learned basic concepts but need a nudge to get the most of them. An exception to this is any couch to 5K / 10K / marathon style program. The running form is not that complicated at the amateur level, so progress is more about speed and stamina.

Sleep tracking has three hardware requirements: motion sensors, HR sensors and (as already mentioned) enough battery life for the night. This falls under the luxury category because the only people who need it are those trying to diagnose restlessness. Even for the average person, wearing a tracker in bed can provide a great wake up experience. Some devices can be set to wake you up while you sleep lightly, and even if you can’t, a vibrating wrist will definitely get you out of bed faster without disturbing anyone. Garmin offers a related software metric called Body Battery that combines HR, stress, and activity data to determine energy reserves.

A microphone for voice assistants only makes sense if the rest of your tech is tied to the same platform. For example, an Alexa or Google Assistant user could turn on the lights, music, and fan in their home gym with a single command. If you just stop and start training, it’s not worth spending a premium on speech technology alone.

Hardware features alone shouldn’t determine what you buy. Once your requirements are established, the next few steps are to consider reviews, brand reputation, and the quality of the associated phone apps. There are plenty of cheap generic fitness trackers on Amazon, but a more expensive model from a popular brand will pay off in terms of durability and app support. For example, Android users should insist on something attached to Google Fit.

In fact, the app experience is vital – data is meaningless as a confusing jumble of statistics. A high-quality app assesses your fitness in a practical way, explains what different numbers mean and asks you to get better. The best apps will take you on a long-term journey, offering tips and training plans that you will eventually complete. We recommend testing the apps for any devices you’re considering, or at least checking out their ratings and screenshots.

Brand names can cost more, but looking through feature creep can still save you some money. For example, it can be tempting to buy the most powerful tracker within your budget, but even professionals know that some accessories are over the top. If you need more help choosing fitness equipment, check out these articles: