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The best pulse oximeter in 2021

Best pulse oximeter
(Image credit: Getty Images)

Looking for the best pulse oximeter? This guide is here to help you choose the right one - and help show you the best price you can get it for.

Home pulse oximeters are a great tool for keeping on top of your blood-oxygen levels – and are now highly affordable. If your home medical kit consists of nothing more than sticking plasters and antiseptic, you might be surprised such a thing is even possible. For many, though, it is very desirable to monitor blood oxygen saturation (SpO2), a figure which can reveal illness even when the patient isn’t aware of it and do so using optical technology. Definitely something to add to your medicine cupboard alongside the infrared thermometer.

Blood should have an SpO2 of 95-100%. Below 90% is dangerously low and called hypoxemia. A pulse oximeter works a bit like a digital camera, as SpO2 can be detected optically by passing light from an emitter to a sensor somewhere arterial blood is flowing (like the middle finger of the dominant hand). The higher the oxygenation, the fewer light frequencies pass through. The devices also have to compensate for the distance the light is traveling and any ambient light for accurate results.

Certain conditions require regular monitoring, while athletes and pilots can all benefit from having their own devices. In a time when acute respiratory diseases are rampant (SARS, Covid-19) anyone might be able to detect a drop in lung capacity by taking regular readings, though of course you can only help your doctor, not replace them!

The best pulse oximeter in 2021

Best pulse oximeter - Zacurate Pro CMS500 series

(Image credit: Zacurate)

1. Zacurate Pro Series 500DL

Best budget pulse oximeter

Dimensions: 59x37x33mm (2.3 x 1.5 x 1.3 in)
Power: 2xAAA
Reading: 10sec
SpO2 Accuracy: ± 1%
Pulse accuracy: ± 1bpm
Reasons to buy
+Simple to use+Easy to read screen+Suitable for children over 12+Choice of colors
Reasons to avoid
-Batteries not rechargeable

Zacurate’s 500DL is not their first finger pulse oximeter designed for the home market, so they’ve had the chance to address a few issues, not least that the predecessor could only display up to 99% rather than the 100% maximum SpO2. Carrying CE & FDA approval, this device can produce a reading to its large, clear display in 10 seconds, and (according to the manufacturer) is less susceptible to inaccuracies if slightly moved and has better ambient light compensation. The 500DL is intended for adults but can read any fingers large enough, so kids over 12 should be fine. There is no memory, but the batteries should be good for 40 hours worth of reading so even with the ten seconds it takes to shut down after use that one set of AAAs will last a while! We certainly appreciated a silicon cover and lanyard coming in the kit (which cost less than the cover for a new phone).

(Image credit: Wellue)

2. Wellue o2Ring

Best pulse oximeter for extended monitoring

Ring diameter: 50-82mm
Weight: 15g
Water resistance: IP24
Compatibility: iOS 9+, Android 5+, Windows 7/8/10, MacOS 10.5+
Reasons to buy
+Smartphone synchronization+Ideal for long-term monitoring

On the face of it, this is a slightly chunky (3.8cm/1.5in) black polished thumb-ring. A second glance shows you it’s no piece of jewellery though – the discrete built in display giving the game away. Inside the dark pebble is a rechargeable battery providing up to 16 hours of recording, at 1s intervals, of blood oxygen, pulse (BPM), and motion. All your data can be synced over Bluetooth 4 to your App or desktop (the latter offering printing or PDF export). The ring can also be set to vibrate should it drop below the level of your choice. Marketed as an alternative for wrist-worn alternatives, this certainly seems more convenient, though the outlay is considerably more than a simple ‘dumb’ finger measure, but if you’re monitoring your sleep this is an excellent choice (you can also use it without removing nail varnish too, if that’s important to you!).

(Image credit: Hermano)

3. Hermano Baby & Children Digital Fingertip Pulse Oximeter

Best pulse oximeter for kids

Dimensions: 44x26x33mm (1.734 x 1.04 x 1.3 in)
Power: Rechargeable battery
Reading: 10sec
SpO2 Accuracy: ± 2%
Pulse accuracy: ± 2bpm
Reasons to buy
+Child-friendly design+Rechargeable+Ages 1-12
Reasons to avoid
-Cute design won't fool cynical kids

Whether featuring a playful design will fool the kids into thinking this is not a medical device is open to debate. My 4 year old never fell for the sweet taste in kids medicines, and would see right through this. So the styling is never going to make your kids sit still for ten seconds, but it’s still handy to take readings from children from 1 to 12 years (other kids fingertip devices only work from 2 years). Larger ‘adult’ fingertip readers can produce incorrect results if they don’t grip the finger properly, so if your kids are your concern your choices are limited. The 200mAh lithium battery and Type-C USB recharge connector does make rival AAA-powered devices seem a bit ‘old tech’, but there is a bump in price which can’t just be explained by the cartoon penguin/bird.

(Image credit: Apple)

4. Apple Watch 6

Best smart watch with pulse oximeter

Face diameter: 44mm
Weight: 30.5g
Power: Rechargeable
Compatibility: iOS
Reasons to buy
+The best Apple Watch yet+Choice of aluminum, stainless steel, and titanium +Huge choice of colors and strap styles
Reasons to avoid
-Expensive if you are just after pulse oximeter!-You need an iPhone to use many of the features

The latest and best-ever Apple Watch has health at the forefront of its new features. A new sleep app uses motion sensors to measure how you sleep. With personal hygiene being more in our mind than ever before, it will use a motion sensor to time how long wash your hands. And most significantly it adds a pulse oximeter for the first time, using a cluster of four IR LEDs that take a SpO2 measurement in just 15 seconds, and that can monitor the values 24/7. The new Watch OS 7 also makes sure that the VO2 Max values can be used by a range of apps – and you can even get a notification if your VO2 Max drops to lower levels. Of course, there is plenty of other features available with this GPS-enabled watch, enabled by its ever increasing range of optional apps. It’s also worth considering that the Apple Watch 7, with a slightly bigger screen which has just been announced.

(Image credit: Garmin)

5. Garmin Vivoactive 4

Best budget smart watch with pulse oximeter

Face diameter: 45mm
Weight: 50g
Power: Rechargeable
Compatibility: iOS, Android
Reasons to buy
+A great smart watch+Round face design
Reasons to avoid
-Not medical grade

Monitoring blood-oxygen levels is useful for athletes, especially mountaineers who have to be sure they’re coping with dropping oxygen levels at altitude. While the Garmin’s built-in monitor is not medical grade, it can certainly help provide an insight, and of course is complemented by heart rate, body energy, hydration, sleep and stress monitoring among others. The watch also boasts GPS and coaching features to help you train, as well as contactless payments and a music player (if you provide compatible headphones). All that is before you pair with a smart phone for notifications and more, making this a very handy way to keep yourself moving in places you wouldn’t take your phone though, so if you’re thinking of getting a smart watch and want to follow blood oxygen then Apple may have caught up but Garmin were here first and offer both this with a 45mm face, a smaller Garmin Vivoactive 4S  with a 40mm face, and a thinner, lighter Venu watch too. We preferred the ruggedness and battery life of the Vivoactive 4.

(Image credit: Owlet)

6. Owlet Smart Sock 2

Best pulse oximeter for babies

Base station dimensions: 88mm diameter, 17mm height
Power: Mains power (base station)
Communication: Bluetooth (to base station) & Wi-Fi
Compatibility: iOS 13+ and Android 5+
Reasons to buy
+Elegant design+More comfortable than arm bands+Ages 0-18 months
Reasons to avoid
-Only suitable for babies up to 25lb-Needs charging every 16 hours of use (but charges fast)

Some parents will baulk at the cost of a device with an 18-month lifespan (once your baby hits 25lbs or 11kg, they’ve outgrown it), but for nervous first-time parents this product can provide significant peace of mind, and makes it possible to move the baby into its own room sooner. The ‘sock’ (there are three in the box, washable, and of increasing size), sends data from its pulse oximeter to a base station via Bluetooth and, if all is within parameters, the flat puck-like base station glows a reassuring green. If there is cause for alarm it’ll turn red and you’ll be notified by and alarm and by your smart phone. A nice touch is that a yellow warning just plays a nursery rhyme, before going the whole red. It isn’t cheap, but might make a lot of sense for those whose pediatricians have detected specific concerns, like apnea. It’s also wise to buy from a trusted store that will accept returns if the baby’s skin reacts badly to the sock.

(Image credit: Garmin)

7. Garmin Enduro

Best adventure-grade sport-watch with pulse ox

Face diameter: 51mm
Weight: 61g (Titanium) or 71g (Steel)
Power: Solar-charged battery
Compatibility: iOS, Android
Reasons to buy
+Sports watch+Solar powered+Rugged case design
Reasons to avoid
-Not medical grade

Garmin’s pulse oximeter makes a great deal of sense on a solidly-built watch like this since it can be used to determine how your body is acclimatizing to an upcoming challenge like altitude. Because of the battery life, the pulse oximeter can optionally be used all day and for sleep monitoring. The information is combined with heart rate data to help track your sleep and keep an eye on your stress. Not only that, but the watch is equipped with an array of other tech to help you push your body (and get adequate rest times). Apple Watch owners will be deeply envious of the up-to 80 hours which this device can keep going for, topping itself up via solar energy (if you’re lucky enough to be training in good sunlight for about 3 hours, that is). The  Enduro has a distinct look, so won’t be for everyone, but the always-on screen and solid design is ideal for sports fanatics.

(Image credit: Wellue)

8. Wellue Checkme o2 Max Wrist Monitor

Get blood oxygen as a measure of sleep health

Face diameter: 48 x 28 x 18 mm
Weight: 25g
Power: Li-Po, 72hrs
Compatibility: iOS, Android, PC, Mac
Reading: : every 0.5sec
SpO2 Accuracy:: ± 2%
Pulse accuracy:: ± 2bpm
Reasons to buy
+Unique way of helping with sleep monitoring++Gain extra data: pulse rate and motion+Alert system
Reasons to avoid
-Designed for comfort by may irk some light sleepers-Expensive for just SpO2 data

Worn on the wrist, this monitor collects and records information on SpO2, heart rate and motion into a built-in memory (it has four ten-hour memories). There is also a rubber piece around the thumb, which is too soft to cause numbness but is something you might only want to wear if you think there is cause to collect this data. By taking readings at intervals of half a second, the tracker is able to build up a pretty rich set of data which you can upload directly to a computer via a USB port (also how you charge it) or view on your phone screen. It can store up to 4 nights before it starts recording over old data. The app has extra features, like adjusting the device’s alert threshold, which is handy as it can be set to vibrate if there is cause for medical alert (but  does mean a phone is essential).

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Adam Juniper

With over 20 years of expertise as a tech journalist, Adam brings a wealth of knowledge across a vast number of product categories, including timelapse cameras, home security cameras, NVR cameras, photography books, webcams, 3D printers and 3D scanners, borescopes, radar detectors… and, above all, drones. 

Adam is our resident expert on all aspects of camera drones and drone photography, from buying guides on the best choices for aerial photographers of all ability levels to the latest rules and regulations on piloting drones. 

He is the author of a number of books including The Complete Guide to Drones, The Smart Smart Home Handbook, 101 Tips for DSLR Video and The Drone Pilot's Handbook