Published September 10, 2026 10:23AM<\/p>\n<\/div>\n
Wearables have become a near-constant companion for many Americans. According to a 2026 study<\/a>, nearly 107 million people in the United States own one. People track their steps, workouts, and recovery, and increasingly look to those numbers to tell them how their bodies are doing. But for some\u2014particularly people with darker skin tones\u2014there\u2019s a nagging question: Can I trust what my device is telling me?\u00a0\u00a0<\/em><\/p>\n There\u2019s a good reason to ask. A 2025 review<\/a> of smartwatch accuracy studies found significant variability in how wearable devices performed across skin tones. According to one study included in the review, a major smartwatch brand measured heart rates within five beats per minute (bpm) across a full spectrum of skin tones. Other devices, however, underestimated heart rate by ten to 15 bpm in darker-skinned users during moderate to vigorous exercise. Researchers also found large discrepancies in heart rate readings during cycling and resistance training in people with dark skin.<\/p>\n While heart rate metrics help people gauge workout intensity<\/a> and how quickly their heart recovers after exercise, heart rate readings can also be lifesaving. An irregular heartbeat may indicate serious cardiovascular issues that can lead to blood clots, stroke, and heart failure<\/a>, and should be flagged to a doctor. An inaccurate reading could miss these red flags.\u00a0This issue is not news to wearable companies as getting accurate data from darker skin is a known challenge\u2014one that requires extra effort from wearable makers to ensure the data is reliable.<\/p>\n Outside<\/i> contacted eight major wearable tech companies, including Oura, Apple, WHOOP, Google, and Polar, to find out how they\u2019ve worked to address the wearable skin-tone problem. Here\u2019s why wearables can struggle to get accurate readings on dark skin, and how these companies say they\u2019ve improved their tech to ensure better accuracy across skin tones.<\/p>\n Most smartwatches and rings rely on a type of technology called photoplethysmography (PPG), which uses optical sensors. Those sensors detect light to measure blood flow<\/a>.<\/p>\n A typical PPG device shines green light into your skin. (If you take a peek at the underside of your fitness watch, you can probably spot those green flashing lights.) Hemoglobin\u2014a small protein in your blood<\/a> that carries oxygen from the lungs to the rest of the body\u2014absorbs some of that light, and the rest is reflected back onto the sensor. As blood moves through your vessels, the device measures changes in the reflected light to estimate your heart rate.<\/p>\n The catch is that melanin, the pigment that gives skin its color, also absorbs and scatters some of the device\u2019s light. The more melanin in the skin, the more light is absorbed. This makes darker skin tones more vulnerable to data loss compared to lighter skin tones, according to that 2025 review.<\/p>\n Categorizing skin tone can be tricky because it\u2019s subjective. But dermatologists often rely on the Fitzpatrick Scale. This scale is the dermatology industry standard classification for skin tone groups, according to a study published in the HCA Healthcare Journal of Medicine<\/i><\/a> in February 2026. The scale is based on people\u2019s self-reported observations of how likely they are to sunburn and tan. That data helped classify skin tone into six categories, from Type I to Type VI. Type I skin is the lightest and burns easily and doesn\u2019t tan; Type VI is the darkest and tans easily and almost never burns.<\/p>\n Despite the scale\u2019s widespread use, it\u2019s considered flawed, as that same 2026 study noted that its reliance on self-perception and cultural and societal influences complicates categorization.<\/p>\n Even though skin tone can affect watch accuracy, it\u2019s not the only<\/i> factor that can lead to an inaccurate reading. \u201cNoise is the biggest issue,\u201d Michael Rosenberg, MD<\/a>, a cardiac electrophysiologist who studies wearables in the division of cardiology at the University of Colorado Anschutz Medical Campus, told Outside<\/i>. Noise, Rosenberg said, includes tattoos, body hair, hydration levels, sweat, and residue from lotions or sunscreens. He said that wrist size, skin temperature, and even freckles can impact readings.<\/p>\n Improving wearable tech accuracy takes real intention; however, Apple, Oura, WHOOP, Polar, Google, and other wearable companies have made it a priority.<\/p>\n Emily Capodilupo<\/a>, senior vice president of research, algorithms, and data at WHOOP, said they\u2019re intentional about ensuring their studies include people across all six Fitzpatrick values. WHOOP is a wearable company that sells a tiered membership<\/a>, where customers pay an annual fee that includes their screenless device and access to their app\u2019s metrics and analysis.<\/p>\n \u201cWhen we notice a population\u2014skin tone, gender, age\u2014where we think we\u2019re struggling performance-wise, we overrepresent that group in the data collection efforts, and that\u2019s a very effective technique for improving algorithms,\u201d Capodilupo told Outside<\/i>.<\/p>\n Capodilupo also said WHOOP has specifically designed an algorithm to compensate for how melanin absorbs light. She said that algorithm is constantly validated and updated. The device monitors how much signal it gets back and adjusts the LED brightness accordingly. If the signal is weaker, the LED intensity increases. This approach comes with a trade-off, she explained. More powerful LEDs use more battery. \u201cThat\u2019s a trade that we\u2019re willing to make because we want to make sure that we can stand by the data that we provide,\u201d Capodilupo said.<\/p>\n Apple\u2019s strategy is similar. The company says\u00a0that it addresses the issue at the software and hardware level, including by adjusting how much light is transmitted into the skin and how strongly the return signal is amplified. They also said that in every generation of Apple Watch, software and hardware design factors are driven by ensuring users with the darkest skin tones get a strong signal and equivalent performance.<\/p>\n At Oura, the company\u2019s smart ring uses the same PPG technology. Senior vice president of science Shyamal Patel, PhD<\/a>, said the product\u2019s advantage is that the palm side of the finger tends to have more consistent pigmentation than the wrist. The finger, he said, also provides access to larger arteries, which can produce a stronger signal than what you can measure on the wrist with the same kind of hardware setup.<\/p>\n That doesn\u2019t solve for everything, though. Patel said the ring\u2019s \u201csmart sensing\u201d capability means there are a number of paths the light can travel through the skin. The device continuously evaluates which path is producing the strongest signal and adjusts accordingly.<\/p>\n In a statement via email, Raija Laukkanen, PhD, said that optical heart measurements have improved over the years largely due to better sensor technology, ergonomics and algorithms. Laukkanen is the director of science collaborations at Polar, a wearable tech company that offers watches based on activity types and other products like chest straps. \u201cOptical measurement remains a practical and effective option for continuous heart rate tracking and everyday training. For situations where precision is the priority, electrocardiogram (ECG) remains our recommended approach,\u201d she wrote.<\/p>\n Unlike PPG tech, which relies on light sensors to collect heart rate data, ECG or EKG measures electrical heart signals directly through the skin, so it isn\u2019t affected by pigmentation and is considered the gold standard in heart rate testing. The Polar H10<\/a> chest strap uses ECG to monitor heart rate during physical activity where real-time data is necessary. (Some Apple Watch, Polar watches, and WHOOP models offer on-demand ECG readings.)<\/p>\n Patel said Oura is exploring new ways to characterize skin tones, such as the Monk skin tone scale (MST)<\/a>, which is a ten-tone visual scale that captures a fuller spectrum of darker skin. Patel\u2019s team focuses on improving algorithms to better translate sensor data into useful metrics that can tell users about their overall health and well-being.<\/p>\n Patel also said they intentionally collect data in a broad range of locations worldwide to support diversity. \u201cWe need to continue expanding the standards and then continue innovating on how we measure and validate the data,\u201d Patel said.<\/p>\n Apple also incorporates a spectrophotometer, which helps measure color more objectively. In addition to the standard Fitzpatrick assessment, researchers can use this lab instrument to measure the exact amount of light reflected at different wavelengths.<\/p>\n In a statement via email, a Google spokesperson said, \u201cGoogle Health takes accuracy very seriously and continuously conducts studies to rigorously test the accuracy of our products among diverse groups of users. We also focus on recruiting a diverse testing population from around the globe for wear testing during our development cycles for Google wearables including Fitbit and Pixel Watch devices.\u201d<\/p>\n Though wearables provide a wealth of data on users\u2019 health and wellness, Rosenberg said it\u2019s important to remember that wearable devices are still commercial products, not medical ones. So, it\u2019s reasonable to expect occasional inaccuracies, but he said they do detect overall trends pretty well.<\/p>\n To get the most accurate readings, the experts contacted for this story said there are a few things that are within your control: keep a snug fit so that the sensor is in contact with the skin, make sure the sensor isn\u2019t sitting directly on a bone, wipe the sensor regularly so it remains free of sweat and residue from lotions, try to keep the sensor away from any tattoos, and install recent device and app updates. If your device isn\u2019t working properly or starts producing strange results, it\u2019s probably best to ditch it for a new one.<\/p>\n Wearables aren\u2019t one-size-fits-all. As the technology evolves, continued research and more representative data will be key to ensuring everyone can trust the numbers on their devices.<\/p>\n Want more\u00a0<\/b>Outside<\/i><\/b>\u00a0health stories?\u00a0<\/b>Sign up for the Bodywork newsletter<\/b><\/a>. And for tips on how to train, fuel, and recover better,\u00a0<\/b>sign up for the Sweat Science 101 newsletter<\/b>.<\/b><\/p>\nWhat Skin Tone Means for Wearable Accuracy<\/h2>\n
How Skin Tone Is Categorized<\/h3>\n
How Wearable Tech Companies Have Addressed and Continue to Improve Data Accuracy on Darker Skin<\/h2>\n
Algorithm Fixes and Updates to Improve Sensor Capabilities<\/h3>\n
Capturing a Wider Spectrum of Skin Tones<\/h3>\n
Getting the Most Out of Your Wearable Tech<\/h2>\n