Why are recovery metrics different on different trackers?

This often happens when you switch trackers or use two at once: Whoop Recovery 45%, Oura 68%, Garmin Body Battery 52%. Which one is true?

In short, this is normal. All three can be right within their own logic because they measure different inputs and combine them in different ways.

What a recovery metric is

Recovery, Readiness, Body Battery, Sleep Score are derived metrics. They combine signals like HRV, resting heart rate, sleep, activity, sometimes temperature or subjective input, and output one number.

The formula behind that number differs by brand. There is no single standard or correct formula. It is an interpretation of data, not a direct measurement of one thing.

Why the numbers differ

Different algorithms. Whoop emphasizes HRV and nighttime heart rate patterns. Oura weighs temperature, sleep structure, and activity over several days. Garmin blends stress, activity, sleep, and HRV. The same state can look different across these lenses.

Different HRV windows. Whoop uses RMSSD across the night. Oura often uses deep sleep segments. Garmin uses multiple windows. Even if the physiology is the same, the method changes the number.

Different scales. Whoop uses a 0-100 percentage with its own color ranges. Oura uses a similar scale but with different thresholds. Garmin uses Body Battery as a unit scale. The numbers are not on the same ruler.

Different calibration. Each device learns your baseline over time. In the first weeks the number can be less stable, then it settles as the device adapts.

Different sensors. Optical sensors vary by brand, and wrist or ring placement changes signal quality. Small differences in raw data become larger in aggregated scores.

Which is true

Each metric is true within its own definition. Whoop reflects nighttime recovery signals, Oura reflects readiness based on sleep and temperature, Garmin reflects a battery style view combining stress and activity. These are different descriptions of the same day.

How people usually read this

Many people focus on one tracker as the main reference and treat others as secondary. Comparing absolute values across brands often creates confusion because the scales are different.

Trends are usually more useful than single numbers. A week of decline on one device and a week of decline on another often tell the same story even if the absolute values look far apart.

It is also common for feelings to diverge from the number on a given day. Metrics capture a slice of the picture, not the whole context.

Connection with other signals

If different trackers disagree on recovery but HRV and sleep are low on all, it likely reflects a real dip. If HRV and sleep look normal across devices but recovery scores differ, the gap is usually algorithmic rather than physiological.