Apple Watch SE 3 Review: Sleep And Heart Rate For £219, Without An ECG

What £219 buys: the screen, the chip and the waterproofing

The SE 3 comes in two case sizes and one material. The 44mm case fits wrists from 140 to 245 mm at 32.9 g, or 33.0 g with cellular; the 40mm takes 130 to 200 mm at 26.3 g. The 44mm adds £30, 6.6 g and a larger display, 977 sq mm against 759. Both run the S10 chip with 64GB of storage.

The display is Always-On Retina with OLED and LTPO, peaking at 1,000 nits, under Ion-X glass Apple rates 4x more crack resistant than the SE 2's. Water resistance is rated to 50 m, which Apple's footnote describes as shallow-water use such as swimming in a pool or the sea, and not scuba diving or waterskiing. The controls include the Digital Crown with haptic feedback plus single tap, double tap and wrist-flick gestures, and the watch carries Fall Detection and Crash Detection.

The sensors and alerts that stay on Series 12

Apple's SE 3 specification page lists a second-generation optical heart sensor and then stops. There is no electrical heart sensor, and the consequence is spelled out in Apple's own footnote on the UK buy page: the ECG app is available on Series 4 and later, excluding Apple Watch SE models, and is meant for people 22 and over. Without that sensor, no software update can add the ECG app to the SE 3. The SE 3 does keep high and low heart rate notifications and irregular rhythm notifications.

The SE 3 also has no blood-oxygen sensor, so no Blood Oxygen app, which Apple labels wellness-only. Series 12 starts at £369 and Ultra 4 at £749. The £150 between the SE 3 and Series 12 also buys a brighter display, up to 2,000 nits against 1,000, and an S11 chip.

The UK comparison table lists hypertension notifications for Series 12 and Ultra 4 and marks them absent on the SE 3. Apple's feature-availability page names the United Kingdom for the feature but warns it may not be available on Series 12 or Ultra 4 in your region while regulatory clearances are in process, so confirm it before paying for it.

Sleep apnoea notifications, sleep score and cycle tracking

Apple's footnote states sleep apnoea notifications are available on Apple Watch Series 9 and later, Ultra 2 and later, and SE 3, and that the feature is meant to detect signs of moderate to severe sleep apnoea in adults 18 and up who have never had a diagnosis. It flags signs rather than diagnosing anything, which makes it a prompt to see a doctor rather than an answer.

Alongside it the SE 3 logs sleep stages and a sleep score, and carries a temperature sensor, which feeds cycle tracking. The advanced cycle-tracking app adds fertile-window estimates, retrospective ovulation estimates and perimenopause and menopause support; Apple's own footnote limits cycle-deviation notifications including perimenopause to people 40 and older, and states the app should not be used for birth control or to diagnose a condition.

18 hours, 32 in Low Power Mode, and what the charging claim measures

Apple rates the SE 3 at up to 18 hours of normal use, up to 32 hours in Low Power Mode including sleep tracking, and up to 7 hours of outdoor workout. The 18-hour figure comes with a published protocol: 300 time checks, 90 notifications, 15 minutes of app use, and a 60-minute workout with music played from the watch over Bluetooth. The low-power figure uses a more demanding protocol over 32 hours, with 430 time checks, 130 notifications, 20 minutes of app use, a 60-minute workout and six hours of sleep tracking. Series 12 is rated up to 24 hours and up to 38 in Low Power Mode.

Fast charging is quoted in three ways: about 45 minutes to reach 80%, 15 minutes for up to 8 hours of normal use, and 8 minutes for up to 8 hours of sleep tracking. The last two are the arithmetic behind wearing it overnight and topping it up while you shower. Apple measured them with its Magnetic Fast Charger to USB-C cable and a 20W USB-C power adapter, and notes that charge time varies with the adapter.

The £70 cellular question, and what it unlocks

Cellular is a £70 add-on at either size, taking the 40mm from £219 to £289 and the 44mm from £249 to £319. Apple's connectivity block spells out the trade: with GPS you make calls and send texts with your iPhone nearby, and with GPS + Cellular you can do it with just the watch. It is also the only way to use Apple Watch For Your Kids, which Apple says needs a GPS + Cellular model and lets a parent set up a child's watch from their own iPhone.

For an adult who carries a phone everywhere, the GPS model covers the usual jobs; the spec page lists the same L1 GPS with GLONASS, Galileo, QZSS and BeiDou under All Models, so cellular adds connectivity, not location. It needs a mobile plan, and Apple's chart names EE, O2, Three and Vodafone for the UK, with eligibility decided by each provider and pay-as-you-go accounts possibly unsupported. Both models support 2.4GHz Wi-Fi networks only.

Returns, the one-year warranty and the £49 repair

Apple takes standard hardware back within 14 calendar days of delivery if you change your mind, and sends card refunds to the bank within five business days of receiving the watch. Apple's one-year limited warranty covers the watch against defects in materials and workmanship. Batteries that wear down over time, cosmetic damage and accidents sit outside it. Repaired parts carry 90 days or the rest of that first year, whichever is longer. Apple's footnote adds that under English law consumers have up to six years from delivery to claim a free repair or replacement for goods that do not conform with the contract, subject to eligibility.

AppleCare+ with Theft and Loss for the SE 3 is £2.99 a month or £29.99 a year, with up to two theft and loss claims every 12 months. An accidental-damage repair carries a £49 excess, theft and loss £89. AppleCare also replaces the battery at no extra charge when its capacity drops below 80 per cent, which is the coverage the base warranty leaves out.