You wake up, reach for your phone, and there it is: a number telling you how you slept before you've even decided how you feel. That number is your sleep score, and for all the weight we give it, most of us have only a fuzzy idea of what it actually measures.
Here's the plain answer, plus everything that number is and isn't. We'll cover what a sleep score is, how your device works it out, what counts as a good one, how the major trackers differ, and the part nobody likes to admit: how accurate these scores really are. The goal is to help you read your score without letting it run your morning.
What is a sleep score?
A sleep score is a single number, almost always on a 0-to-100 scale, that sums up how well you slept the night before. Instead of making you interpret a wall of charts on heart rate and sleep stages, your wearable boils all of it down into one easy grade. Higher is better, and the idea is simply to give you a quick read on whether last night helped or hurt.
It's a convenience, in other words, not a medical measurement. That distinction matters, and we'll come back to it.
How is a sleep score calculated?
Under the hood, your device is watching a handful of signals all night and feeding them into an algorithm. The exact recipe varies by brand, but most scores draw on the same ingredients: how long you slept, how much time you spent in each sleep stage (light, deep, and REM), how efficiently you slept versus lay in bed awake, how restless you were, your sleeping heart rate, and how consistent your timing was.
Your device can't peer directly into your brain the way a lab can, so it infers all of this, mostly from movement and heart rate. The Oura Ring adds body temperature to the mix. Those inputs get weighted and combined into the number you see at breakfast.
What's a good sleep score?
The rough rule of thumb across most devices is that 80 or above is good, the 70s are fair, and below 60 is poor. Fitbit, for example, tells users that most people land somewhere between 72 and 83, so if your typical night sits in that range, you're in good company.
Don't chase a perfect 100. As Fitbit notes, those top scores are designed to be rare, the kind of thing you might see after an unusually flawless night, not a nightly target. A steady stream of scores in the 80s is a much healthier goal than an obsession with hitting triple digits.
Sleep scores by device
Every brand grades on its own curve, which is exactly why your friend's Oura score isn't comparable to your Fitbit number. Here's how the major ones work.
- Fitbit. According to Google's Fitbit support, your overall score (0–100) is the sum of three sub-scores: time asleep, deep and REM sleep, and "restoration," which blends your sleeping heart rate and how much you tossed and turned. Fitbit sorts the result into Excellent (90–100), Good (80–89), Fair (60–79), and Poor (below 60).
- Oura. Oura builds its score from seven contributors, including total sleep, sleep efficiency, restfulness, REM sleep, deep sleep, how quickly you fell asleep, and your sleep timing. Per Oura's own guidance, 85 or above is "optimal" and earns a little crown, 70 to 84 is good, and anything under 70 is a nudge to prioritize rest.
- Apple Watch. Apple's Sleep Score, introduced with watchOS 26, keeps things simpler with just three factors: sleep duration (worth up to 50 points), bedtime consistency (up to 30), and interruptions during the night (up to 20). Your total then falls into descriptive bands from low up to high or excellent, and Apple has been refining exactly where those cutoffs sit.
- Garmin. Garmin also uses a 0-to-100 score, factoring in total sleep, time in REM and deep sleep, movement, and stress, and labels it poor, fair, good, or excellent.
One useful takeaway hides in Apple's math: bedtime consistency alone is worth nearly a third of the score. Going to bed around the same time each night is one of the most effective and most overlooked things you can do.
How accurate are sleep scores?
This is where honesty helps. Wearables are genuinely good at some things and noticeably shaky at others.
On the basics, they're reliable. Research comparing consumer trackers to polysomnography, the clinical lab sleep study, has found that devices detect whether you're asleep or awake with high accuracy and estimate your total sleep time to within roughly half an hour. So "you slept about seven hours" is a number you can mostly trust.
The breakdown into stages is a different story. Studies put the accuracy of stage-by-stage classification far lower, and devices have a known habit of overestimating deep sleep. So treat the precise "you got 1 hour 12 minutes of deep sleep" figures as educated guesses, not gospel. The Sleep Foundation makes the broader point plainly: wearables show promise, but they aren't sensitive enough to score sleep stages with clinical accuracy, and a sleep score is not a diagnosis.
The most important thing is not to let the number stress you out. Researchers have even coined the term "orthosomnia" for the anxiety that comes from chasing perfect sleep data. If your score says you slept badly but you feel fine, trust how you feel. And for sleep problems that won't quit, like chronic insomnia, loud snoring, or daytime exhaustion, a doctor is the right next step, not a wearable.
How to improve your sleep score
The unglamorous truth is that the habits that raise your score are just good sleep habits.
Start with consistency, since it counts for a lot and is easy to overlook. Going to bed and waking up at roughly the same time anchors your body clock and, as Apple's scoring shows, counts for a big chunk of the number. Next, give yourself enough runway: the National Sleep Foundation recommends seven to nine hours for adults, and simply being in bed long enough lifts most scores on its own. Finally, mind the inputs that quietly wreck sleep quality, especially alcohol and late-day caffeine, both of which can fragment your night and keep your heart rate up while you sleep.
Do those three things and the number tends to follow. Chase the number directly and you'll mostly just lose sleep over it.
FAQ
What is a good sleep score?
On most devices, 80 or above is good, the 70s are fair, and under 60 is poor. Fitbit says most people score between 72 and 83.
What is a good sleep score on Fitbit?
Fitbit rates 90–100 as Excellent, 80–89 as Good, 60–79 as Fair, and below 60 as Poor, and notes that the typical user lands in the 72–83 range.
Are sleep scores accurate?
They're reliable for whether you slept and roughly how long, but much less precise about individual sleep stages, and they often overestimate deep sleep. A sleep score is a useful trend, not a medical diagnosis.
How can I raise my sleep score?
Keep a consistent bedtime, aim for seven to nine hours, and cut back on alcohol and late caffeine. Those fundamentals move the number more than anything else..