POLAR
Pick Polar if
- Train by HRV and recovery score
- You don't mind wearing a chest strap (e.g. the H10)
- You compete and need lab-grade variability
Polar vs Fitbit
Polar wins on athletic-grade HRV, recovery, and training load. Fitbit wins on signal breadth — sleep stages plus ECG and AFib screening from one wrist device.
POLAR
17/27API signals exposed
Sport watch / chest strap
vs
fitbit
16/27API signals exposed
Daily-wear watch + scale
QUICK VERDICT
If you race or run hard intervals, Polar's chest strap gives you the cleanest HRV signal MyBodyAI can read. If you want one watch handling everything from sleep stages to AFib screening, Fitbit covers a wide signal set without a second device.
COVERAGE BY CATEGORY
Where each brand actually wins
Per-category breakdown of API signals.
SIGNAL BY SIGNAL
The full matrix
| Signal | Polar | Fitbit |
|---|---|---|
| Heart & Vitals | ||
| Resting HR | ✓ | ✓ |
| HRV | ✓ | ✓ |
| SpO2 | ✓ | ✓ |
| Respiratory Rate | ✓ | ✓ |
| Skin Temperature | ✓ | ✓ |
| Body Temperature | — | — |
| Blood Pressure | — | — |
| ECG · AFib | — | ✓ |
| Sleep | ||
| Sleep duration | ✓ | ✓ |
| Sleep stages | ✓ | ✓ |
| Sleep score | ✓ | — |
| 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 | ✓ | ✓ |
| Body fat % | — | — |
| Muscle mass | — | — |
| Hydration | — | — |
Verified against vendor developer documentation.
WHICH ONE FOR YOU
Pick the one that matches your priority
fitbit
Pick Fitbit if
- You want a single wrist device for everything
- ECG and AFib screening matter to you
- Sleep stages + SpO2 + skin temperature in one place
POLAR+fitbit
Pick both if
- Polar chest strap during structured workouts
- Fitbit Charge or Pixel Watch 24/7 for sleep + SpO2
- MyBodyAI merges both feeds; richer source wins per field
FAQ
Frequently asked questions
Should I choose Polar or Fitbit?
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.
Which one tracks more health signals?
Polar tracks 17 of the 27 signals I compare, Fitbit tracks 16. The matrix above breaks it down by category, and they often win different categories.
Is it worth switching from Polar to Fitbit?
Only if Fitbit wins the categories you actually care about. If you already own Polar and it covers your main goal, the upgrade is rarely worth it. The matrix above shows exactly what changes.
How did you compare Polar and Fitbit?
From each brand's official spec sheets and support pages, cross-checked against independent reviews like DC Rainmaker and The Quantified Scientist and peer-reviewed accuracy studies. Signal-level edge cases are noted in the matrix, not hidden behind a single check mark.
WHERE TO BUY
Check prices at the source
Direct links to each vendor's store. No affiliate links.
- POLAR Official store Check at Polar →
- fitbit Official store Check at Fitbit →
MORE COMPARISONS
Explore other pairs
OPTIONAL — IF YOU WANT MORE
Want one place that merges both feeds?
MyBodyAI merges these signals into Biological Age, Recovery and 9 other indices.
Try MyBodyAI free →