Apple Watch Ultra 4 vs Samsung Galaxy Watch9
4 questions both answer, side by side. Every answer is backed by the dated sources at the bottom.
Side by side
Can a smartwatch work without your phone nearby?
Apple Watch Ultra 4 supports 5G (RedCap) and LTE, with antennas for cellular and satellite.
Good to know: Data plan required; 5G only in select markets.
Galaxy Watch9 LTE models can use GPS without a paired phone; non-LTE models need a Bluetooth connection.
Good to know: Needs a carrier plan for LTE.
Can you talk to an AI assistant on your smartwatch?
Apple Watch Ultra 4 has Siri powered by Apple Intelligence.
Good to know: Maker's description.
Galaxy Watch9 uses Google Gemini to answer questions, organize tasks and reach information across apps by voice.
Good to know: Maker's description.
How long does a smartwatch battery last?
Apple rates Apple Watch Ultra 4 at up to 50 hours of normal use and 84 hours in Low Power Mode; 15 minutes of charging gives up to 18 hours.
Good to know: Maker's figures.
In Notebookcheck's review, Galaxy Watch9 used about 60 to 70% of its charge in 24 hours with the always-on display, a short GPS workout and sleep tracking. A full recharge took almost 1.5 hours.
Good to know: One reviewer's test on one unit; watch size not stated. Samsung's US page gives no battery hours.
Which phone does a smartwatch need?
Apple Watch Ultra 4 requires an iPhone 11 or later with iOS 27 or later.
Good to know: Apple lists iPhone models only.
Galaxy Watch9 is an Android watch; some features need a compatible Samsung Galaxy phone, and Bedtime Guidance needs Android 13 or later.
Good to know: Check each feature's requirements on Samsung's page.
How we know (3 sources)
Apple Watch Ultra 4 tech specs (read Oct 24, 2026): up to 50 hours of normal use, up to 84 hours in Low Power Mode, up to 18 hours of workout tracking; 15 minutes of charging gives up to 18 hours. Supports 5G (RedCap) and LTE, with cellular/satellite antennas; data plan required. Siri powered by Apple Intelligence. Requires iPhone 11 or later with iOS 27 or later.
Read the sourceGalaxy Watch9 review (read Oct 24, 2026) that calls battery life its main weakness. With the always-on display, a short GPS workout and sleep tracking with blood oxygen, the watch used about 60 to 70% of its charge in 24 hours. A fully drained watch took almost 1.5 hours to recharge. Watch size tested not stated.
Read the sourceUS Galaxy Watch9 page (read Oct 23, 2026): from $379.99; Google Gemini answers questions and organizes tasks by voice. LTE models can use GPS without a paired phone; non-LTE models need a Bluetooth phone connection. Some features need a compatible Samsung Galaxy phone; Bedtime Guidance needs Android 13 or later. No battery hours on the page.
Read the source