Apple Watch SE 3 Review: Sleep and Heart Rate for A$399, Without an ECG

What A$399 buys: the screen, the chip and the water rating

The SE 3 comes in two case sizes and one material. The 44mm case fits wrists from 140 to 245 mm and weighs 32.9 g; the 40mm fits 130 to 200 mm at 26.3 g. The bigger case adds A$50, 6.6 g and display area, 977 sq mm against 759. Both run the S10 chip with a 4-core Neural Engine and 64GB of storage.

The display is Always-On Retina with OLED and LTPO, under Ion-X glass Apple rates four times more crack resistant than the SE 2's, and water resistance is rated to 50 m, swim-proof. In the box are the watch, a band and a 1 m Magnetic Fast Charger to USB-C Cable; there is no power adapter, so the fast-charge figures assume a USB-C brick you already own.

What the A$250 step to Series 12 buys

Apple Australia's SE 3 spec sheet lists a second-generation optical heart sensor and stops there. Series 12 adds an electrical heart sensor and a blood-oxygen sensor, and its footnote spells out the consequence: the ECG app runs on Series 4 and later, excluding Apple Watch SE models, for people 22 and over. Apple lists both the ECG app and the Blood Oxygen app as available in Australia, so the gap is the hardware, and no update can close it on an SE 3.

Hypertension notifications are a messier comparison here than in the US. Apple lists Australia for the feature, the SE 3 does not support it, and Apple's footnote says it may not yet be available on Series 12 or Ultra 4 while clearances are in process; the Australian Series 12 spec sheet does not list it. Buy Series 12 for the ECG and blood oxygen, not on the assumption that hypertension alerts come with it.

The rest of the A$250 goes on the screen and battery. Series 12 comes in 42mm and 46mm with 970 and 1,196 sq mm of display, so the smaller one roughly matches the larger SE 3, at 2,000 nits peak to 1,000. It runs the S11 chip, is rated for 24 hours of normal use and 38 in Low Power Mode against 18 and 32, and adds a depth gauge and water temperature sensor. Cellular costs A$150 extra on Series 12, against A$90 on the SE 3.

Sleep apnoea notifications, sleep score and cycle tracking

Sleep apnoea notifications run on Series 9 and later, Ultra 2 and later, and the SE 3, and Apple lists Australia among the regions where they are switched on. The feature looks for signs of moderate to severe sleep apnoea in people 18 and over who have never been diagnosed, and Apple's footnote says it is not meant for screening or diagnosis, which makes it a reason to book a GP appointment rather than an answer.

Alongside it the SE 3 logs sleep stages and a sleep score, and its temperature sensor feeds the advanced cycle-tracking app, with fertile-window estimates, retrospective ovulation estimates and perimenopause and menopause support. None of this needs the sensors Series 12 adds, which is why the sleep side of the two watches is closer than the heart side.

18 hours, 32 in Low Power Mode, and how Apple measured it

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 workout tracking. The 18-hour figure comes with a published routine of 300 time checks, 90 notifications, 15 minutes of app use and a 60-minute workout with music played from the watch; the 32-hour figure stretches a heavier routine, including six hours of sleep tracking, over a day and a third.

Fast charging is quoted two ways: 15 minutes for up to 8 hours of normal use, or 8 minutes for up to 8 hours of sleep tracking. Those are the numbers behind wearing it overnight and topping it up during breakfast. Apple measured them with the included cable plugged into its 20W USB-C Power Adapter and notes that charge times vary with the adapter.

The A$90 cellular option, and what it unlocks in Australia

Cellular takes the 40mm SE 3 from A$399 to A$489 and changes two things. The watch gets RedCap 5G and 4G LTE bands plus international emergency calling, which Apple lists for Australia. It also opens Apple Watch For Your Kids, which Apple offers in Australia and which needs a GPS + Cellular watch to pair with a child who has no iPhone.

For an adult who carries a phone everywhere, the GPS model already maps runs and walks on its own L1 GPS, without the phone. The A$90 earns its keep when the phone stays home on purpose, a run without a pocket or a child's first watch. Both models join only 2.4 GHz Wi-Fi networks.

Returns, the warranty and the A$99 repair

Apple Australia takes the SE 3 back within 14 days of delivery if it is in original condition with all parts, accessories and packaging, so a few nights of sleep tracking to check fit and the band is realistic, but keep the box. Apple's one-year limited warranty covers manufacturing defects and sits on top of the Australian Consumer Law guarantees, which Apple's own warranty page says it adds to rather than replaces.

Accidental damage is outside the warranty. Under AppleCare+ a repair carries an A$99 excess, A$119 for Ultra and Hermès, and theft and loss A$179 on the plan that covers it. Those excesses are the number to weigh against a watch that costs A$399 new.