WHOOP

WHOOP 4.0

Armbandreleased 2021MyBodyAI · No integration yet

WHOOP 4.0 is an armband from 2021, sitting in the premium band. The maker does not publish a list price for it. It is no longer sold new. It stays in this comparison because plenty of people are still wearing one.

It reads 13 of the 33 signals this comparison tracks. Nothing at all from body composition. Rarer readings it does take: sleep efficiency.

By sensor class: 5 at high accuracy and 4 at consumer grade. That grade is my classification of the hardware, not a lab test. Those readings come from an optical heart rate sensor, an optical blood oxygen sensor, a skin temperature sensor and an accelerometer. Blood oxygen is measured through the night, not continuously through the day.

Its 5 days per charge are the 10th longest of the 11 devices of its kind here that publish a figure. Rated IP68 / 10m, fine for swimming. A WHOOP membership subscription is required to use it.

Discontinued (replaced by 5.0/MG May 2025); HR/SpO2/skin-temp, no ECG/BP/GPS/VO2max/steps.

Key specs

Price

included with a membershipWHOOP membership

Battery

5 d~5 days; slide-on waterproof battery pack (worn while charging)

Display

No display

Water resistance

IP68 / 10m (swim)

GPS

None

Weight

28 g

Works with

iOS + Android

Subscription

Required · WHOOP membershipband only works with paid membership; no standalone hardware price

not confirmed: weight

Official store →

What it tracks

Heart & vitals

Resting heart rateHigh accuracy

HRVHigh accuracy

Blood oxygen (SpO2)Consumer

Respiratory rateConsumer

Skin temperatureConsumer

Sleep

Sleep durationHigh accuracy

Sleep stagesHigh accuracy

Sleep scoretracked

Sleep efficiencytracked

Activity

CaloriesConsumer

WorkoutsHigh accuracy

Fitness

Training loadtracked

Recovery / readinesstracked

Screening, not a medical diagnosis. This device offers SpO2. These are wellness screening features, not a substitute for a clinical evaluation.

Sources

https://www.dcrainmaker.com/2021/11/whoop-platform-review.html

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If you want to go deeper

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MyBodyAI reads Fitbit, Oura, Polar and Withings by logging in, and Garmin from a data export, then builds daily recovery, sleep, load and immune scores, a biological age estimate, and early warnings. Optional, and separate from this comparison.

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