Devices

Apple, Garmin, Whoop, Oura, and Fitbit Compared

Five brands measuring overlapping metrics under five different names, with real design philosophies behind the differences.

Every metric page on this site already covers device-specific terminology and accuracy where the research supports it. This page is the index: what each brand actually calls things, where the naming genuinely diverges even when the underlying metric doesn't, and which brand has shipped something none of the others have yet.

The five devices

Breadth without synthesis

Apple Watch

Eight metrics, no composite daily score. No native recovery or stress score.

Athlete-first

Garmin

Keeps "VO2 Max" as the direct label. Layers Training Readiness and Training Load on top. No ECG.

Synthesis-first

Whoop

Nearly everything feeds one Recovery Score. No ECG. Glucose integration explored but not shipped.

Sleep-first

Oura

Sleep Score and Readiness Score anchor everything else. First brand here with a live glucose integration.

Step-tracking pioneer

Fitbit

Original consumer step counter. Reports blood oxygen as a relative graph instead of a percentage.

Same metric, different name

What it measures	Apple	Garmin	Whoop	Oura	Fitbit
Cardio fitness (VO2 max)	"Cardio Fitness"	"VO2 Max"	Not surfaced as a standalone number	Part of Cardio Capacity	"Cardio Fitness Score"
Composite daily wellness score	None	"Body Battery"	"Recovery Score"	"Readiness Score"	"Daily Readiness Score" (Premium)
Blood oxygen	On-demand spot check	Spot check or continuous	Tracked, added on 4.0 hardware	Overnight only	Relative variation graph, not a percentage
ECG	FDA-cleared app	Not offered	Not offered	Not offered (ring form factor)	Sense 2 only
Continuous glucose monitoring	Not native	Not native	Explored, not shipped	Live via Dexcom Stelo (2025)	Not native

The composite-score row is the one to read carefully. A real peer-reviewed evaluation found Body Battery, Recovery Score, Readiness Score, and Daily Readiness Score are not methodologically equivalent to each other, despite the overlapping names and inputs. Comparing a Whoop Recovery Score against an Oura Readiness Score on the same morning isn't scientifically sound, even though both claim to answer a similar question. Source: Fischer & Reiter, "Readiness, recovery, and strain: an evaluation of composite health scores in consumer wearables," 2025, doi:10.1515/teb-2025-0001.

Cross-brand comparisons

How Accurate Is Fitbit, Garmin, and Whoop Sleep Tracking?

A look at what validation studies find when comparing sleep-stage accuracy across three major wearable brands against lab polysomnography.

Wearable ECG Accuracy: Why Devices Disagree So Often

Why single-lead consumer ECG readings across brands produce inconclusive results more often than people expect, and what the research says about it.

Does Apple Watch's Heart Rate Accuracy Extend to HRV?

Apple Watch heart rate and HRV don't score the same on accuracy against lab-grade monitors. Here's what the research testing both actually found.

Does Wearable Temperature Tracking Actually Detect Ovulation?

A look at what validation studies on wrist and ring temperature sensors, used across several of the brands on this page, actually found.