The Apple Watch Series 12 is now available, two years after the Series 10 introduced the current thinner design. But is it worth upgrading?While last year's Series 11 brought just four changes, the Series 12 is a much more substantial update, with a new chip, twice as much RAM, redesigned health sensors, exclusive health and audio features, tougher cover glass, 5G connectivity, and new case materials.The Series 12 starts at the same $399 price as the Series 10 did in 2024. Apple has now discontinued the Series 10, but remaining units may still be available from third-party retailers and on the refurbished or second-hand market. Here are all of the key hardware and feature differences between the Apple Watch Series 10 and Apple Watch Series 12:Apple Watch Series 10Apple Watch Series 12S10 chip (2024)S11 chip (2026)2GB RAM4GB RAMElectrical heart sensorHealth Sensing System with second-generation electrical heart sensorThird-generation optical heart sensorFourth-generation, always-on optical heart sensorPeriodic background heart rate trackingHigh-frequency background heart rate tracking every five secondsHeart rate variabilityRecovery HRV and overall HRV, measured up to 24x more frequentlyVitals app with heart rate, respiratory rate, wrist temperature, and sleep durationVitals app with heart rate, respiratory rate, wrist temperature, sleep duration, and HRV, plus daytime vitalsReadiness app with daily score and recommendationStandard step trackingRedesigned pedometer model with more accurate all-day step trackingSteps watch face complicationAudio Intelligence, including Live Rewind, Siri Recap, Sound Recognition, and faster ShazamIon-X front glass (aluminum models)Ceramic Shield 2, 60% tougher than Ion-X (aluminum models)Metal and sapphire crystal backCase-matched metal or ceramic and zirconia backAluminum or titanium caseAluminum, titanium, or ceramic caseAluminum: Jet Black, Rose Gold, and SilverAluminum: Dark Bronze, Light Gold, Black, and Space GrayTitanium: Slate, Gold, and NaturalTitanium: Radiant Gold and NaturalCeramic: Pearl White and Night BlueHermès: Silver titaniumHermès: Silver and Radiant Gold titaniumLTE and UMTS (cellular models)LTE and 5G RedCap (cellular models)Up to 18 hours of normal useUp to 24 hours of normal useUp to 36 hours in Low Power ModeUp to 38 hours in Low Power Mode15 minutes of charging for up to eight hours of normal use15 minutes of charging for up to 12 hours of normal useEight minutes of charging for up to eight hours of sleep trackingFive minutes of charging for up to 10 hours of sleep trackingNow discontinuedFrom $399Design and DisplayThe Series 12 retains the same basic design introduced by the Series 10, including 42mm and 46mm size options and a 9.7mm-thick case. Nevertheless, Apple has made some subtle dimensional changes. Both sizes are now 1mm wider, and every equivalent aluminum or titanium configuration is between 2.1 and 3.3 grams heavier than its Series 10 counterpart.At the same time, the display has shrunk slightly. Resolution is unchanged, but the active display area is around 2% smaller on both sizes. The combination of a wider, receded case and smaller display produces thicker borders around the screen.Here is how the 46mm models compare:46mmApple Watch Series 10Apple Watch Series 12Dimensions46mm x 39mm x 9.7mm46mm x 40mm x 9.7mmResolution416 x 496 pixels416 x 496 pixelsDisplay area1,220 sq mm1,196 sq mmAluminum (GPS)36.4 grams39.5 gramsAluminum (Cellular)35.3 grams38.6 gramsTitanium41.7 grams44.9 gramsThe 42mm models compare as follows:42mmApple Watch Series 10Apple Watch Series 12Dimensions42mm x 36mm x 9.7mm42mm x 37mm x 9.7mmResolution374 x 446 pixels374 x 446 pixelsDisplay area989 sq mm970 sq mmAluminum (GPS)30 grams32.2 gramsAluminum (Cellular)29.3 grams31.5 gramsTitanium34.4 grams36.5 gramsThe Series 12 also marks the return of a ceramic Apple Watch for the first time since the Series 5 Edition in 2019. The ceramic models are larger and heavier than their aluminum and titanium counterparts:Ceramic46mm42mmDimensions47mm x 41mm x 9.85mm43mm x 37mm x 9.85mmPearl White51.3 grams41.7 gramsNight Blue52.9 grams42.8 gramsIs It Worth Upgrading?Two generations on, the Series 12 represents a meaningful cumulative upgrade over the Series 10, but it is far from an essential replacement. The two models share the same basic design, display brightness, resolution, storage capacity, core safety features, and more. The Series 10 is only two years old, and supports watchOS 27 and ‌Siri‌ AI, so it remains a capable and modern Apple Watch.For existing Series 10 owners, upgrading is easiest to justify if health and fitness tracking is a priority. The Series 12's high-frequency heart rate sensing, Recovery HRV, daytime vitals, Readiness score, and improved step tracking provide substantially more useful training and recovery data. Sound Recognition may be compelling for deaf or hard of hearing users, while 5G, faster charging, tougher cover glass on aluminum models, and the ceramic case provide additional reasons for some buyers to upgrade.Beyond this, the practical difference between the two devices is relatively small. The Series 12 is also slightly wider and heavier, and its active display area is around 2% smaller despite retaining the same resolution. Its 24-hour battery rating is also not directly comparable with the Series 10's 18-hour figure because Apple changed its testing methodology. If your Series 10 still comfortably lasts through the day and you are satisfied with its existing health features, there is no strong general-purpose reason to replace it.Which to Buy Today?At its $399 starting price, the Series 12 is the obvious choice over a Series 10 selling for anything close to its original price. The newer model offers a better health sensing system, twice as much RAM, the S11 chip, exclusive Audio Intelligence features, faster charging, 5G, and more case options. A saving of only $50 to $100 is unlikely to compensate for giving up those improvements.The Series 10 becomes attractive when it is at least around $150 cheaper than an equivalent Series 12 and is in excellent condition. It still offers an always-on display, ECG, temperature sensing, sleep apnea and hypertension notifications, advanced workout tracking, and ‌Siri‌ AI. Buyers should pay particular attention to battery health and warranty coverage, since replacing a degraded battery could quickly erode the saving.Related Roundup: Apple Watch 12Buyer's Guide: Apple Watch (Buy Now)Related Forum: Apple WatchThis article, "Apple Watch Series 10 vs. Series 12 Buyer's Guide: Should You Upgrade?" first appeared on MacRumors.comDiscuss this article in our forums