Health band or health bracelet: what it measures, what it costs and what it cannot do

What is a smart band or health bracelet?

Search for a “health bracelet” and two different things come up. One is a connected band that wraps round the wrist and records data from sensors. The other is a magnetic or copper bracelet sold for aches and pains. They share a word and little else. This guide covers the connected kind first, then looks at what the trials on the magnetic kind found.

No NHS or MHRA page read for this guide defines a “smart band”, so there is no official definition to quote. The descriptions here come from the makers’ own UK product pages, read on 21 October 2026. Polar sells its Loop as a screen-free band that tracks heart rate, sleep and activity day and night.¹⁵ Amazfit describes its Helio Strap as heart rate tracking without a screen, as opposed to a watch.¹⁶

Some bands do have a display. Google’s UK store lists the Fitbit Charge 6 as a tracker with a screen and a claimed battery life of 7 days.¹⁷ So “band” covers both screenless and screen models. Read a product page for what is on the wrist, not just for the name.

One point of regulation is worth knowing. The MHRA says that in the UK many software products are regulated as medical devices, and points to the intended purpose set by the maker.¹¹ A wellness band is sold for general tracking, not for diagnosing or treating a condition. That is the sense in which this guide uses the word “wellness”.

Smart band, smartwatch, ring or chest strap: how do they differ?

The makers’ pages give a clear split on one point: a screen. A screenless band such as the Loop or the Helio Strap leaves out the display and the notifications that come with it.¹⁵¹⁶ A band with a screen, such as the Charge 6, shows you data on the wrist.¹⁷

No institutional source read for this guide compares bands with smartwatches, rings or chest straps, so this page does not rank them. If you want a chest strap comparison, see wrist vs chest strap heart rate. If you are weighing a ring, the guide to smart rings sets out what was read on that form.

What does a health bracelet actually measure?

Most connected bands record heart rate, movement and sleep. What matters is how far each estimate can be trusted, and the three studies read for this guide give a cautious picture.

• Heart rate at the wrist. A systematic review of 10 studies, with 469 participants, looked at wrist-worn heart rate across skin tones. Four studies reported lower accuracy on darker skin, four found no effect and two were mixed. The authors called the evidence preliminary and inconclusive.¹²
• Sleep. A rapid review of 29 studies found consumer sleep devices moderately accurate for how long you sleep. REM and deep sleep estimates were particularly unreliable. The review said devices may help with general tracking, especially duration and circadian timing, but that most were not validated on varied or clinical groups.¹³
• Energy burned. A meta-analysis from the University of Leeds covered 60 studies. It found that the accuracy of energy expenditure estimates from wrist and arm devices depends on the type of activity. Adding heart rate or heat sensing to movement sensing reduced the error in most activities.¹⁴

None of these studies tested Elio, so none of them says how it performs. Treat band figures as estimates that are useful for trends over weeks, and be most cautious about sleep stages. For more on what the numbers mean, see the guides to sleep score, normal resting heart rate and heart rate variability.

Screenless or with a display: which suits you?

The choice is about habit rather than health. A screenless band asks you to open an app to see anything, which suits someone who wants less on the wrist. A band with a display answers a quick glance. The makers’ pages show the trade in battery life: up to 8 days for the Loop, up to 10 days for the Helio Strap, 7 days for the Charge 6.¹⁵¹⁶¹⁷

Elio’s own page says it lasts 15 days between charges and recharges magnetically.¹⁹ That magnet is only the charging connector. It has nothing to do with the therapeutic magnetic bracelets covered further down.

Water resistance is also worth checking. Polar gives the Loop a WR30 rating for swimming and bathing, and Amazfit gives the Helio Strap 5 ATM.¹⁵¹⁶ Both are the makers’ own figures.

How to choose a health band: seven questions

1. Screen. Decide whether you want a display or an app-only band, as above.
2. Battery. Compare the claimed days between charges, bearing in mind they are the maker’s figure.^15161719
3. Subscription. Polar says the Loop has no monthly fees and no locked features.¹⁵ For more on this, see best fitness tracker without a subscription. Amazfit says no monthly subscription is required.¹⁶ Google’s page for the Charge 6 says some features, such as the Daily Readiness Score, come with Google Health Premium, with three months included at purchase.¹⁷
4. Skin. The NHS says contact dermatitis can be triggered by some metals, including nickel, and makes the skin itchy, blistered, dry and cracked.¹⁰ See a GP if a strap causes symptoms that persist or keep coming back.
5. App. A band is only as useful as the app you actually open.
6. Export. Whether you can take your data out was not stated on the pages read, so check before you buy.
7. Returns. The return policy of each band was not read for this guide, so check it at the point of sale.

What does it cost over three years? A worked example

A sticker price hides a subscription. A fair way to compare is to add the purchase price to 36 months of any monthly fee. The formula is: three-year cost = purchase price + 36 × monthly fee.

Three bands with no subscription

The Polar Loop shows £149.50 on Polar’s UK page. With no monthly fee, the three-year cost is £149.50 + 36 × £0 = £149.50, or £149.50 ÷ 36 = £4.15 a month.¹⁵

The Amazfit Helio Strap shows £99.90, tax included, with no monthly subscription required. That is £99.90 over three years, or £99.90 ÷ 36 = £2.78 a month.¹⁶ The gap between the two is £149.50 − £99.90 = £49.60.

The Fitbit Charge 6 shows £139.99 on Google’s UK store. Without any subscription, that is £139.99 ÷ 36 = £3.89 a month.¹⁷

Adding a subscription

Google’s page for Google Health Premium shows “From £7.99”, but the page read does not say whether that is per month or another period.¹⁸ A three-year total with a subscription therefore cannot be worked out from the sources, and this page does not guess.

To see how the formula behaves, take a made-up band: £100 to buy and £8 a month. Then 36 × £8 = £288, and £100 + £288 = £388. These numbers are invented to show the arithmetic and are not a real product.

Prices were read on 21 October 2026 and can change. For Elio, the price is shown on the product card on this page, kept in one place so it stays current.

What a wellness band cannot do

A band that counts beats is not a heart monitor in the medical sense. The Elio page says its measurements are indicative and tells readers to see a healthcare professional if they have symptoms. It does not claim to diagnose or to replace a prescribed device.¹⁹

The NHS gives the same advice from the other side. It says symptoms of a heart rhythm problem do not necessarily mean you have one, and to see a GP if you are unsure.²⁰ It describes palpitations as usually harmless, but says to get help if they keep happening or come with other symptoms.⁸

• A band does not diagnose a heart problem. Use it as a diary of your own numbers, and take any worry to a GP.
• It does not replace urgent help. If you have chest pain that feels tight or like squeezing, the NHS says to call 999 and not to drive yourself to A&E.⁷
• Sleep stage charts are the weakest output. REM and deep sleep estimates were particularly unreliable in the 2026 review.¹³
• Skin tone can matter. Some studies found lower heart rate accuracy on darker skin, others found no effect, and the evidence is still preliminary.¹²

Magnetic and copper bracelets: what did the trials find?

These bracelets are sold for the pain of osteoarthritis, so the evidence comes from arthritis trials. Both results below come from journal abstracts and a university press release, not from the full papers.

In 2009 the University of York reported a trial of 45 people aged 50 or over with osteoarthritis. Each wore four devices in a random order over 16 weeks: two magnetic straps of different strength, a demagnetised strap and a copper bracelet. The researchers found no meaningful difference between the devices on pain, stiffness or physical function.¹² A secondary analysis of one pain subscale favoured the standard magnetic strap, but the authors noted no adjustment for multiple testing.² The lead researcher put any benefit people felt down to a placebo effect.¹

An earlier trial, reported in the BMJ in 2004, had 194 people aged 45 to 80 with hip or knee osteoarthritis in five rural general practices wear a standard magnet, a weak magnet or a dummy bracelet for 12 weeks. Pain fell more with the standard magnet than with the dummy, by a mean of 1.3 points (95% confidence interval 0.05 to 2.55), but the authors judged it uncertain whether that was a specific effect or a placebo effect.³ A separate 2008 study of 116 people with osteoarthritis or rheumatoid arthritis found that people were more likely to expect pain relief from a stronger magnetic bracelet, so a weak magnet may not work as a fair placebo.⁴

The NHS says to see a GP if osteoarthritis symptoms persist.⁵ For mild symptoms it lists regular exercise, losing weight if you are overweight and suitable footwear.⁵ It also says there is a lack of medical evidence that complementary therapies such as acupuncture and aromatherapy work.⁶

Wearing it day and night: fit, skin and charging

No NHS page or study read for this guide covers wearing a band day and night, so the advice here is limited to what was read.

Fit is set by the maker. Amazfit gives the Helio Strap a wrist range of 145 to 205 mm and a weight of 20 g.¹⁶ Check your own wrist against the range before you buy.

Charging time is the price of continuous tracking. A band that lasts 8 days needs a charge slot you will actually keep to, and a gap in wear is a gap in the data. Elio’s page gives 15 days between charges.¹⁹

On skin, the NHS says contact dermatitis usually shows up within a few hours or days of contact.¹⁰ If a strap makes your skin itch or blister, take it off and, if the symptoms persist or keep coming back, see a GP.¹⁰ Whether pacemaker wearers should avoid magnetic charging was not read in a British source, so ask your care team.

Frequently asked questions