Garmin Forerunner 265 vs Apple Watch Ultra 3: Which GPS Watch Wins?

Overview

The Garmin Forerunner 265 is a dedicated running watch for serious recreational athletes who want deep training metrics and multi-week battery life at a mid-range price. The Apple Watch Ultra 3 is a premium device that tries to do everything: flagship smartwatch, endurance sports tracker, and dive computer in one titanium case. These two watches share some overlap in GPS capability but differ sharply in price, battery strategy, and platform philosophy.

Specs at a glance

Price tier: Forerunner 265 at $449 vs Ultra 3 at premium flagship pricing
Weight: Forerunner 265 at 47g vs Ultra 3 at 61.4g
GPS battery: Forerunner 265 up to 20h standard GPS, 13h multi-band; Ultra 3 approximately 18h standard GPS, 72h low-power mode
Smartwatch battery: Forerunner 265 rated 13 days; Ultra 3 rated 18h in typical use
Display: Forerunner 265 with 1.3-inch AMOLED; Ultra 3 with always-on microLED and flat sapphire crystal
Water resistance: Forerunner 265 at 5 ATM (50m); Ultra 3 at 100m with EN13319 dive certification
GPS chipset: Both use dual-frequency L1/L5 multi-constellation GNSS
Heart rate sensor: Both use wrist optical PPG for heart rate and HRV; neither uses electrical ECG for continuous HR

GPS and tracking accuracy

Both watches use dual-frequency GNSS and perform well in challenging environments. The Forerunner 265 handles urban canyons and dense forest reliably, with accuracy roughly equivalent to other watches on the same chipset generation. Garmin applies aggressive post-processing and map matching, which smooths data but can obscure raw signal behavior.

The Ultra 3 pushes ahead in benchmark testing. In satellite acquisition and connectivity trials, it outperforms the Garmin Fenix 8 across multiple metrics. In open-water swim GPS accuracy, it directly beats the Garmin Forerunner 965. For triathletes, that swim-leg GPS performance is a concrete advantage, since wrist-based GPS during open water is where most watches struggle most.

On road running courses, review data for the Ultra 3 shows strong results across structured benchmark protocols. The Forerunner 265 is accurate but does not match the Ultra 3's raw GPS performance in head-to-head testing.

Battery life

This is where the two watches split sharply. The Forerunner 265 lasts up to 20 hours in standard GPS mode and around 13 hours with multi-band active. In smartwatch mode it runs for approximately 13 days. That means most users charge it once a week and never think about battery during any single activity.

The Ultra 3 offers roughly 18 hours in standard GPS workout mode, enough for a Half Ironman with careful management but a hard stop for full Ironman and ultra-endurance events. Its 72-hour low-power mode extends range but reduces GPS fidelity. As a daily smartwatch, the Ultra 3 needs nightly charging. If you train daily and also wear your watch overnight for sleep tracking, battery management becomes a real constraint.

For athletes: who wins?

Road running: Forerunner 265. The training load metrics, structured workout tools, and two-week battery mean you plan less and run more. The 265 is built around this use case.
Trail running: Forerunner 265 for multi-day or ultra events where battery is critical. Ultra 3 for day efforts where GPS accuracy and the action button matter more than endurance.
Triathlon: Ultra 3. Its open-water swim GPS accuracy advantage over the Forerunner 965 is documented, and the 265 sits below the 965 in Garmin's lineup. For athletes who want one device across all three disciplines and in daily life, the Ultra 3 justifies its cost.
Recovery tracking: Both use wrist optical PPG for HRV. Independent testing flagged the Forerunner 265's HRV data as unsuitable for rigorous athlete monitoring. The Ultra 3's HRV implementation has not been flagged with the same concern in available review data, though neither device matches a chest ECG strap for precision.

Verdict

For most runners, the Forerunner 265 is the smarter buy. It costs significantly less, lasts two weeks on a charge, and delivers all the training metrics a serious recreational runner or triathlete needs. The Ultra 3 is the better GPS device in raw accuracy terms and wins for open-water swim tracking, but that advantage only matters if you are racing at a level where those margins count.

Buy the Forerunner 265 if you train daily, care about sleep and recovery data without nightly charging friction, and do not need the Ultra 3's smartwatch ecosystem. Buy the Apple Watch Ultra 3 if you are a triathlete who wants one device for racing and daily life, train on the Apple fitness platform, or need dive certification and the best available wrist GPS for open water.