WHOOP Recovery: what goes into the percentage and how far to trust it

WHOOP Recovery is a daily percentage calculated from the previous day and your sleep. WHOOP's developer documentation calls it "a daily measure of how prepared your body is to perform." This page sets out what WHOOP says goes into it, then checks the inputs against independent studies.

The bands

The inputs WHOOP names

• Heart rate variability. WHOOP's support material says it records HRV only during sleep and calculates it as RMSSD.
• Resting heart rate, taken from sleep.
• Respiratory rate during sleep.
• Sleep duration and quality.
• Skin temperature and blood oxygen, which WHOOP lists among Recovery inputs on current hardware.

Each is judged against your own baseline, so a green day means your numbers look good for you, not good against a population chart.

What is proprietary

WHOOP does not publish the weights given to each input, the length of the baseline windows in its current algorithm, or the function that turns deviations into a percentage. As with any consumer score, the inputs can be validated; the composite cannot.

How good are the inputs?

A note on independence. The authors of the 2022 sleep-lab study belong to a research group that receives funding and equipment from WHOOP, which the paper declares; WHOOP was not involved in the design or reporting. The 2020 respiratory rate paper was written with WHOOP employees and shareholders. Neither fact makes the results wrong, but readers should know it. The 2022 heart rate and HRV values also came from WHOOP raw beat-to-beat data processed by the researchers, not from the number shown in the app.

What moves Recovery

• Alcohol. In 4,098 Finnish employees wearing beat-to-beat monitors, an HRV-based recovery measure in the first three hours of sleep fell by 9.3, 24.0 and 39.2 percentage points after low, moderate and high intake.
• Illness. Respiratory rate and resting heart rate rise and HRV falls, often before symptoms.
• Training. High Strain days often lead to lower Recovery the next morning, particularly with short sleep.
• Short sleep. Sleep feeds directly into the calculation.
• Medicines that raise heart rate, including GLP-1 receptor agonists. See wearable data on a GLP-1.

The newer inputs

Skin temperature and blood oxygen are the most recent additions. Both are relative signals on consumer devices. Skin temperature is useful as a deviation from your own baseline: in the TemPredict study of 63,153 ring users, adding continuous temperature to a model built on overnight data raised its ability to detect COVID-19 (the AUC) by 4.9 percent. Wrist blood oxygen is less accurate than a clinical fingertip oximeter, particularly when oxygen is low; see blood oxygen. Neither should be read on its own from a single night.

Respiratory rate is the least discussed input and one of the steadiest: in healthy young adults its night-to-night variation over two weeks was usually under 10 percent.

Why baselines make Recovery noisy at first

Because Recovery compares you with yourself, the first weeks of wear are the least reliable. Resting heart rate is very stable within a person once a baseline exists: in a study of 92,457 wearable users, most people never had a week where it moved by 10 bpm or more. HRV is noisier, which is why sports scientists monitoring athletes use rolling 7-day averages rather than single mornings. A practical reading of Recovery uses the same idea: look at the week, not the day.

Using it well

Treat Recovery as a summary to check, not an instruction to obey. A red morning after a late night of drinking tells you something you already knew. A red morning with no obvious cause, especially with a raised respiratory rate, is a more useful signal and a reason to take it easy and watch for symptoms. A run of yellow and red days through a training block is expected; a run that persists after you back off is worth attention. And because the score is relative to your baseline, it says nothing about how fit you are compared with anyone else.

WHOOP pairs Recovery with Strain, which measures load. Oura's equivalent is the Readiness Score and Garmin's closest is Body Battery.

Logging it

WHOOP connects to Peptide AI directly through wearable integrations. Recovery, HRV, resting heart rate and sleep appear on the same timeline as the dose log and the training log, which makes it easier to separate a protocol effect from a hard week.