Readiness score explained: what the number is built from, and how to use it

What is a readiness (or recovery) score?

A readiness score is a morning number from a wearable. It squeezes several overnight signals into one figure that is meant to say how recovered you are and how much strain you might take on. Different makers use different names: Oura calls theirs Readiness, WHOOP calls theirs Recovery, and Garmin offers Body Battery.¹²³

Oura describes its Readiness Score as a reflection of how balanced your recovery and activity are.¹ A qualitative study of regular exercisers describes these consumer scores as derived from heart rate variability (HRV) and built to be easy to read, with a percentage and colour codes.⁴

Readiness and recovery are brand names for the same general idea. They are not standard measurements, and none of the pages read gives a shared definition. That is why this guide spends most of its time on what each maker publishes about its own score.

If you want the underlying signals explained first, start with heart rate variability and normal resting heart rate. Both are ingredients in the scores below. For how a sleep-only number is built, see sleep score explained.

What goes into the number?

Each maker publishes a list of inputs, but none of the pages read for this guide gives the weight of each input. That matters, because the same inputs can produce very different scores depending on how they are weighted.

Notice what is missing. No page read gives the formula, and none lists how much a hard night of sleep weighs against a high resting heart rate. A good score tells you that the mix looked favourable to the maker’s model. It cannot tell you which ingredient did the work.

Oura, WHOOP and Garmin: how do they differ?

Oura Readiness: a score measured against your own history

Oura says the nightly inputs include your lowest resting heart rate, when it occurred, and your average body temperature. Longer-term inputs include HRV, sleep and the balance between activity and rest.¹ For the “balance” contributors, it compares a weighted 14-day average with your average over the past two months.¹

Oura also says a score below 70 suggests you may benefit from prioritising rest and recovery, and that some variation in the score is normal.¹ It reads a higher average temperature as a possible sign of stress on the body, such as illness, and a resting heart rate above your usual as a sign of incomplete recovery.¹

WHOOP Recovery: a percentage with three colours

WHOOP reports recovery as a percentage each morning and sorts it into green, yellow and red.² It links recovery to a suggested level of daily “Effort”.² That suggestion is the maker’s own recommendation, and this guide read nothing that tests it.

WHOOP also states that the average recovery of its members is around 58%.² That is the maker’s figure and the page gives no method, so it is not a benchmark to hold your own number against.

Garmin Body Battery: an energy reserve through the day

Garmin describes Body Battery as a tool to help you monitor your personal energy resources around the clock.³ It analyses heart rate, HRV and movement continuously while the device is worn.³ Garmin says illness, alcohol and residual stress can stop the battery from fully recharging overnight.³

Garmin treats an occasional low-energy day as no cause for alarm, and suggests looking for causes if the battery stays low all the time.³ It adds that a low battery does not mean you cannot exercise, though hard effort in that state could be counterproductive over time. That last view is Garmin’s own position.³

Garmin’s framing is the clearest contrast with the other two. Body Battery is something you can check through the day. WHOOP says it calculates recovery each morning, and Oura’s Readiness Score is a daily score.

Why a “70” is not the same on every app

The bands differ in width as well as in position. This is simple arithmetic from the published bands, counting whole points from 0 to 100.

• Oura band widths: Optimal 16 points (85 to 100), Good 15 (70 to 84), Fair 10 (60 to 69), Pay Attention 60 (0 to 59).¹
• WHOOP band widths: green 34 points (67 to 100), yellow 33 (34 to 66), red 34 (0 to 33).²
• A score of 70 is “Good” on Oura’s scale, and a recovery of 70% would be green on WHOOP’s. A score of 66 is “Fair” on Oura’s scale but yellow on WHOOP’s.¹²

So an Oura 80 and a WHOOP 80% do not describe the same state. They come from different inputs, different scales and, at least for Oura, a personal baseline that WHOOP’s page does not describe. Comparing them is like comparing a mark out of 100 in two different exams.

How reliable is a readiness score?

Be careful about what the research does and does not say. The accuracy studies read look at the ingredients of one brand’s ring, not at a brand’s final score, and none of the studies says whether a score predicts how ready you are to train.

On the ingredients, the picture is mixed. In a comparison with a medical-grade electrocardiogram (ECG) in 35 healthy people, the Oura Ring measured nocturnal heart rate and RMSSD accurately, but not the LF components or the LF/HF ratio.⁶ RMSSD is a short-term measure of heart rate variability.

A second study, covering 114 participants in two laboratory sleep studies, looked at the ring’s HRV readings more closely. The median error exceeded 10% in more than half of the participants aged 45 and over.⁷ Accuracy improved with strict quality filters and when readings were averaged over at least 30 minutes or the whole night.⁷

Two limits apply to those studies. They tested one brand’s ring, in studies published in 2022 and 2024, so they say nothing about WHOOP or Garmin, and they may not reflect current ring models. And they test the raw signal, not the score that the app builds from it.

There is one more useful finding about personal data. In 20 elite endurance athletes followed for a year, analysis of the individual was more accurate than group averages.⁸ That study did not examine any brand’s readiness score, and some of its authors hold shares in the app it studied, so use it only for the point that your own history is a better reference than anyone else’s average.

Finally, none of the pages read gives a clinical threshold for these scores. They are product features, and the makers’ own pages are the only description of how they work.

How to use it: trends, not daily verdicts

Oura says some variation in the score is normal,¹ and the study of regular exercisers found that people lean on self-awareness, flexibility and personal judgement when they decide whether to train, while recognising the limits of the device.⁵ The authors also note that research on how people use these scores is limited.⁵ A sensible habit follows from both points: use the score as one input and keep a record of your own.

A worked example with made-up numbers

These scores are invented to show the arithmetic and are not from any source. Suppose 14 mornings give 78, 82, 74, 80, 85, 77, 69, 81, 83, 76, 79, 84, 72 and 80. The total is 1,100, and 1,100 ÷ 14 = 78.6.

Now a morning at 62. That is 78.6 minus 62, or 16.6 points below your 14-day average. As a share of the average, 16.6 ÷ 78.6 = 21.1% lower. This is well outside the spread of the series, which ran from 69 to 85.

A morning at 74 is a different story. It sits 4.6 points below the average, or 5.8% lower, and inside the range of the series. By itself it is not a signal.

The same logic applies whichever brand you use. Look for gaps against your own average, and look for gaps that last several days. A one-day dip in a score that usually swings between 69 and 85 is ordinary noise.

Add the “feel” column and you can check, over a fortnight, whether the number and your own sense of how you are doing tend to agree. If they rarely do, you have learned something about how much weight to give the score.

When the score says rest but you feel fine, and the reverse

Disagreement between the number and your body is normal, and the studies read give no ruling on which to trust. The exercisers in the qualitative study put their own judgement and flexibility first when deciding whether to train.⁵

• Score low, you feel fine. Oura’s own wording is that a score under 70 means you may benefit from prioritising rest.¹ The word is “may”. Garmin takes a similar line: low energy does not rule out exercise, but hard effort when depleted may not help over the long run.³ Both are the makers’ views.
• Score high, you feel poor. Garmin lists illness, alcohol and residual stress as things that can stop an overnight recharge.³ Oura describes its score as a reflection of how balanced recovery and activity are.¹ If you feel unwell, do not let a good number talk you out of it.
• Score and feeling agree. Nothing to resolve. Carry on logging.

The NHS lists lack of sleep and stress among the common causes of tiredness, and suggests aiming for 6 to 9 hours of sleep.¹⁰ A tracker can show a drop in sleep, but the cause is usually found in your week, not in the algorithm. For a reminder of what a night’s sleep looks like, see sleep stages explained, how much sleep you need, sleep debt and heart rate recovery.

What a score cannot tell you

A readiness score is a wellness feature. It does not diagnose illness, check your heart or tell you whether a medicine is affecting you. None of the studies read tested whether a score can detect illness.

The signals feeding the score are also affected by ordinary life. The British Heart Foundation says a normal resting heart rate for adults is usually between 60 and 100 beats per minute (bpm), and that a rate below 60 can be normal in very fit people and can also be due to a medicine such as a beta blocker.⁹ It says lifestyle, such as exercise, alcohol and smoking, affects heart rate, that what is normal varies with age and health, and that someone with a heart condition should ask their doctor what their normal rate is.⁹

The same page lists infections and viruses, anaemia, an overactive thyroid, anxiety and dehydration among the causes of a resting rate above 100 bpm, and says to book a GP appointment if you have symptoms or a fast resting rate.⁹ The BHF page says nothing about HRV or readiness scores, so those topics rest on the makers’ pages and the studies above.

Palpitations are a separate matter. The NHS says they are common and not usually a sign of anything serious, and gives strenuous exercise, lack of sleep, stress, medicines, alcohol and caffeine as causes.¹¹ A tracker that flags an unusual morning does not change that advice.

Finally, the data comes from a device on your wrist or finger. Treat it as an estimate. If you use a ring for HRV, remember that its accuracy in the study above varied with age and with how readings were averaged.⁷

Frequently asked questions