Smartwatches · 2023 · Apple
Apple Watch Series 9 is the generation that brought the double tap gesture, on-device Siri requests and a 2000-nit display with the S9 SiP. It offers electrical and optical heart sensors, temperature sensing, 50 m water resistance and 18-hour battery life. On some watches sold in the US the Blood Oxygen feature was unavailable for a period; it returned in August 2025 with a redesigned version that calculates the reading on iPhone. In independent testing heart rate came close to a chest strap and the display measured 1619 nits. Owners praise the brightness and double tap; battery life is described as one to two days depending on use.
45 mm aluminium case, GPS model; Pink, Midnight, Starlight, Silver and (PRODUCT)RED. The 41 mm, GPS + Cellular and stainless steel (sapphire crystal) versions differ in size and materials.
| Specification | Value |
|---|---|
| Display | Always-On Retina LTPO OLED; up to 2000 nits, as low as 1 nit; 326 ppi |
| Chip | S9 SiP; 64-bit dual-core processor, 4-core Neural Engine |
| Storage | 64 GB |
| Controls | Digital Crown with haptic feedback, side button, double tap gesture |
| Health sensors | Electrical heart sensor, third-generation optical heart sensor, temperature sensing |
| Blood Oxygen (US) | On watches sold in the US without the feature, a redesigned version arrives with iOS 18.6.1 and watchOS 11.6.1; the reading is calculated on iPhone |
| Other sensors | Compass, always-on altimeter, high-g accelerometer, high dynamic range gyroscope, ambient light sensor |
| Location | L1 GPS, GNSS, Galileo and BeiDou |
| Wireless | Wi-Fi 4 (802.11n), Bluetooth 5.3, second-generation Ultra Wideband |
| Battery and charging | Up to 18 hours normal use, up to 36 hours in Low Power Mode; fast charge to about 80% in 45 minutes |
| Durability | 50 m water resistant (ISO 22810:2010); IP6X dust resistant; Ion-X front glass |
| Size and weight | 45 × 38 × 10.7 mm; 38.7 g; fits 140–245 mm wrists |
| Compatibility | iPhone XS or later with iOS 17 or later |
Apple presents Series 9 as a watch with its most powerful watch chip yet, the S9 SiP, delivering a brighter display, the new double tap gesture and faster on-device Siri; some case and band combinations are offered as carbon-neutral products. Apple Newsroom
On Notebookcheck’s 45 mm aluminium test unit brightness measured 1619 nits (Apple says 2000; Series 8 measured about 1017). The display showed 310 Hz PWM flicker. With all measurements and Always-On enabled the watch lasted over a day and a half, and reached two days with Always-On off. With an 18 W adapter it went from 5% to 64% in 30 minutes and was full in about an hour. Heart rate deviated 1.56% from a Polar H10 chest strap at rest and 1.31% on average during exercise; blood oxygen read on average 1.35% higher than a pulse oximeter. The Wi-Fi 4 limit, the quiet speaker and early scratches on the glass were criticised.
Notebookcheck: Apple Watch Series 9 45 mm reviewOn Best Buy’s 45 mm Midnight Sport Loop page there are 1,788 reviews and 97% of buyers recommend it. Of the 19 visible reviews 18 give five stars and one gives four; all are incentivised verified purchases. The bright display, double tap, health tracking and speed stand out. Battery experiences differ: Hass gets about a day, while DadsAllDay says it lasted over two days in the first weeks. BENW writes that the battery has weakened after about three years. Dingding1118 finds the band cheap-looking, and ScottF does not recommend the Sport Loop for people who are often in water.
Best Buy: Apple Watch Series 9 GPS 45 mm customer reviews