Should you buy a Fitbit this Amazon Prime Day?

Fitbit has announced three new models recently: the Sense 2, the Versa 4 and the Inspire 3. 

The Sense 2 is Fitbit's most advanced watch. It comes with ECG and EDA sensors, which allow it to detect atrial fibrillation along with stress levels. It's slimmer and lighter than the previous model, the original Sense but it also has a lot of the same features.

The Versa 4 isn't too dissimilar to the Sense 2, but it lacks the EDA sensor. It has an impressive 40 exercise modes available, which is a larger pool than its older brother the Versa 3, which only offers 20.

The Inspire 3 is a budget entry from Fitbit, which only covers basic health tracking and it doesn't have in-built GPS. It feels fairly similar to its predecessor, the Fitbit Inspire 2, which is currently very cheap. 

The Fitbit Sense 2 is currently the model with the most available features; however, as it's just been released, it's still rather pricey. We actually prefer the Fitbit Sense original for now, which offers perks like a unique EDA sensor for stress levels, but comes in at $100 cheaper. 

The Sense line from Fitbit is basically a smartwatch/tracker hybrid. If you'd prefer something with a more slimline aesthetic, we'd opt for the Fitbit Charge 5, which still packs in a great set of health-monitoring sensors but is significantly cheaper than the Sense models. 

At the moment, the older models of Fitbits have been reduced in price significantly. As these models are being phased out of production (as new models are introduced) stocks might dwindle, so we'd say that now is the right time to buy. They still take advantage of the latest health tracking features, and they're modern enough to sync with new apps, but they're a lot cheaper than usual. 

The newer Fitbit models are at their highest price right now. If you're the sort of person who likes to have the latest version of everything, there's no reason to hold back on buying one of the newer Fitbits; but be warned that prices might tumble in a few months.

The vast majority of Fitbits are waterproof. Some of the older models, such as the original Fitbit Ace, are only splash resistant, which means you can't swim with them. But virtually every model released in the past few years is waterproof up to a depth of 50 metres, so they're great for a session in the pool.

Fitbits can track your movements with their in-built accelerometers and gyroscopes. When you haven't moved for a while, Fitbit will automatically assume you're asleep and start it's sleep monitoring process. 

Fitbits can also monitor your heart rate. There's a little LED built into the back of your Fitbit that flashes onto your wrist; the Fitbit analyzes the light that bounces back from your wrist, to calculate how much blood is pumping through your body. Through this method, the Fitbit is able to track your heart rate. And as different heart rates signify different stages of sleep, Fitbit can use this data to look at how well you're resting during the night. 

For more details, see our piece on how fitness trackers monitor your sleep.