Pick WHOOP if
- Strain and recovery are your daily metrics
- No display matters to you
- Monthly subscription is acceptable
WHOOP is a subscription strap focused on strain and recovery — 19/33 signals, no display. Fitbit is a daily-wear watch reading 22/33 including ECG, AFib, VO2max, plus weight via the Aria scale.
WHOOP and Fitbit serve different users. WHOOP is for athletes who already train by strain and recovery numbers. Fitbit is for everyone else — a watch with screen, ECG, AFib screening, sleep stages, plus a scale ecosystem. Fitbit reads more signals; WHOOP covers fewer but channels them through a model built specifically for training load.
Per-category breakdown of health signals exposed by each vendor's developer API. The number is breadth, not quality.
| Signal | WHOOP | Fitbit |
|---|---|---|
| Heart & Vitals | ||
| Resting HR | ✓ | ✓ |
| HRV | ✓ | ✓ |
| SpO2 | ✓ | ✓ |
| Respiratory Rate | ✓ | ✓ |
| Skin Temperature | ✓ | ✓ |
| Body Temperature | — | — |
| Blood Pressure | ✓ | — |
| ECG recording | ✓ | ✓ |
| AFib detection | ✓ | ✓ |
| Vascular age | — | — |
| Sleep | ||
| Sleep duration | ✓ | ✓ |
| Sleep stages | ✓ | ✓ |
| Sleep score | ✓ | ✓ |
| Sleep efficiency | ✓ | ✓ |
| Sleep apnea index | — | — |
| Activity | ||
| Steps | ✓ | ✓ |
| Active minutes | — | ✓ |
| Calories | ✓ | ✓ |
| Activities | ✓ | ✓ |
| Floors climbed | — | ✓ |
| Distance | — | ✓ |
| Fitness & Recovery | ||
| VO2max | ✓ | ✓ |
| Training load | ✓ | ✓ |
| Recovery / Readiness | ✓ | ✓ |
| Body Battery | — | — |
| Stress (continuous) | ✓ | ✓ |
| Cardiovascular age | — | — |
| Body Composition | ||
| Weight | — | ✓ via Fitbit Aria Air |
| Body fat % | — | — |
| Muscle mass | — | — |
| Hydration | — | — |
| Bone mass | — | — |
| Visceral fat | — | — |
Verified against vendor developer documentation and MyBodyAI backend code. This counts what a brand's API exposes, which is not the same question as what one device measures: the device catalog scores each model's own hardware, so its numbers differ.
Current WHOOP models WHOOP 5.0 (2025), WHOOP MG (2025), all 2 WHOOP devices
Current Fitbit models Google Fitbit Air (2026), Google Pixel Watch 4 (2025), Google Pixel Watch 3 (2024), Fitbit Charge 6 (2023), all 8 Fitbit devices
Pick WHOOP if
Pick Fitbit if
Pick both if
For most people it is one or the other. Both are daily-wear devices that track the same core things, heart rate, sleep and activity, so wearing both is redundant. Use the matrix above to pick the one that wins the categories you care about.
WHOOP tracks 19 of the 33 signals I compare, Fitbit tracks 22. The matrix above breaks it down by category, and they often win different categories.
Only if Fitbit wins the categories you actually care about. If you already own WHOOP and it covers your main goal, the upgrade is rarely worth it. The matrix above shows exactly what changes.
From each brand's official spec sheets and support pages, cross-checked against independent hands-on reviews (DC Rainmaker, the5krunner, Tom's Guide). Signal-level edge cases are noted in the matrix, not hidden behind a single check mark.
Links to each vendor's store. None of them changed any pick above.
MyBodyAI is what I build with these signals — it pulls from any combination of the brands above and derives Biological Age and 12 health indices from the raw numbers. Free to try, no card. It's optional — the comparison above stands on its own.
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