Nobody mentions that at checkout. You pay £200 for the band, and a few weeks later the app wants £9.99 a month to show you numbers the band is already collecting.

So when we tested the five trackers readers ask us about most, we scored them on something the spec sheets leave out: what each one actually costs over two years, and whether it's still on your wrist by the end of it.

All five went on rotation for ninety days and nights - work, training, travel, a stomach bug, and a lot of unremarkable Tuesdays. We compared readings across matching days, checked each night's sleep data against a note we'd written that morning about how we actually felt, ran every battery flat, and added up every subscription.

The short version: the most expensive device didn't win. The one that did held steady readings, went 38 ENTIRE DAYS before I had to charge it (nuts), and locks nothing behind a monthly fee.

Here's how all five finished, and why.

Voltra Air really earns its place through serious health credentials, but presented in a way that actually makes sense. In our testing it kept up with the competition that costs 3-4 times as much, and its Multi-Wavelength PPG sensor - which are a clear upgrade on the single-wavelength sensors found in most budget bands - takes round-the-clock readings of blood pressure, heart rate, HRV, and resting heart rate.

It's among the very few bands that deliver 'blood pressure insights' with no subscription attached - the sort of ongoing record you could genuinely bring to a GP, free, every single day. It also captured complete sleep stages for 38 days straight, over a full month of unbroken sleep data that the Apple Watch, Fitbit, and Garmin can't offer when they need charging every night.

This depth of monitoring usually sits locked behind a £229-a-year membership, or a smartwatch that won't survive till morning. Voltra Air really breaks that pattern. At only £39, it's the most capable screen-free health tracker in our line-up - real health data in something so light you'll forget it's on your wrist.

I'll be straight with you: I went into this expecting to write Voltra Air off entirely.

Everything about it read like a device destined to underwhelm. No screen. A £39 price nobody takes seriously when placed in an industry full of devices costing hundreds. A company I'd never even heard of. And I (quite unfairly) lined it up against the big names, fully expecting it to be the first one back in its box by the end of the week.

Then the week passed, and it was still on my wrist. So was the next one, and the one after that. A 38 days - through packed work stretches, early flights, gym sessions, and the kind of ragged holiday sleep that wrecks your rhythm - and not once did I reach for a charger.

And somewhere in those thirty eight days it stopped being the underdog I was ready to dismiss. The sleep stages finally explained why eight hours in bed still left some mornings feeling hollow. The blood pressure trends put a name to the afternoon brain fog I'd been shrugging off. And heart rate averages I could actually trust let me see the shifts I'd been missing. The weirdest part is, I actually found it easier to understand than some of the others.

Here's what stuck with me. The tracker that genuinely helps your health isn't necessarily the dearest or 'best' one on the shelf - it's the one you'll keep wearing long enough for the data to mean something. At 52, quietly wondering whether my body's aging well or aging fast, this is the first one that actually gave me an answer.

I knew going in that Voltra Air was cheaper. What I didn't expect was quite how wide the gap got once I actually did the sums. The average WHOOP user, I found, stays subscribed for around three years before cancelling - and at £29 a month, that's £1044 handed over just to keep the thing working. I genuinely had to run the maths twice, because it didn't seem right the first time. Three years of subscription fees against a single £39 payment that never asks for another penny. Same wrist, same daily data - one just quietly stops charging you.