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Fitness band

WHOOP Peak (WHOOP 5.0)

Peak membership at $239 a year, including the WHOOP 5.0 device, Wireless PowerPack and SuperKnit band

$239 a yearUS price, checked Oct 13, 2026

Display-free recovery strap sold only as a yearly membership

Check price at WHOOP Full review →

Fitness band

Google Fitbit Air

Classic edition with the Obsidian band, including 3 months of Google Health Premium

$99.99US price, checked Oct 13, 2026

Screen-free $99.99 fitness band with up to 7 days of battery

Check price at Google Full review →

Fitness band

Polar Loop

Night Black with the SoftWeave Textile band (S–L)

$199.99US price, checked Oct 13, 2026

Screen-free band with sleep and recovery scores and no subscription

Check price at Polar Full review →

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Criterion	WHOOP Peak (WHOOP 5.0)	Google Fitbit Air	Polar Loop
US price	$239 a yearChecked Oct 13, 2026 · Price details in the review	$99.99Checked Oct 13, 2026 · Price details in the review	$199.99Checked Oct 13, 2026 · Price details in the review
Three-year ownership estimate	$717 Incomplete known subtotal. Not included: energy use.	$99.99 Incomplete known subtotal. Not included: energy use.	$199.99 Incomplete known subtotal. Not included: energy use.
Choose if	Anyone who wants daily recovery and sleep scores plus WHOOP Age and health alerts, and would rather pay $239 a year than buy a device outright.	You want sleep, heart rate and blood oxygen tracking for about $100 from a 12 g band with no screen.	You want nightly recovery and sleep scores from a band with no screen and no monthly fee.
Main trade-off	It costs $717 over three years with no hardware-only option listed, has no display, and leaves ECG and blood pressure features to the $359-a-year Life tier.	You read everything in the app, and Google's coach costs extra after the 3 free months.	You need your phone for GPS, and Polar lists no skin temperature or blood oxygen sensing.
Key specifications	Membership cost: $239 a year for Peak. One is $199 a year and Life is $359 a year. WHOOP shows only annual pricing. Battery and charging: 14+ days per charge. A full charge of the strap or the PowerPack takes about 2 hours. The Wireless PowerPack slides onto the strap and charges it while you wear it. WHOOP says a fully charged PowerPack holds enough power for up to 30 days to fully charge the sensor. Display and GPS: No display or built-in GPS. You view your data in the WHOOP app. Sensors: WHOOP says its sensors capture data 26 times per second. The pages checked don't name the sensor types. Peak-tier features: Healthspan and Pace of Aging (WHOOP Age), a real-time Stress Monitor, and Health Monitor with health alerts. Peak also includes all One features: Recovery, Sleep and Strain scores, steps and activity, haptic alarm, women's hormonal insights, VO2 max and heart rate zones, and Natural Cycles integration. In the box: WHOOP 5.0 device, Wireless PowerPack and SuperKnit band. One members get a wired Basic Charger and CoreKnit band instead.	Battery and charging: Up to 7 days per charge. A full charge takes about 90 minutes, and 5 minutes gives about a day. Google suggests charging every few days to keep tracking without gaps. It doesn't publish the test conditions behind the 7-day figure. Sensors: Optical heart rate monitor, 3-axis accelerometer and gyroscope, red and infrared sensors for blood oxygen, a device temperature sensor and a vibration motor Health tracking: 24/7 heart rate, plus resting heart rate, heart rate variability, breathing rate, blood oxygen and skin temperature variation. It counts steps, Active Zone Minutes, distance and calories, and gives a Sleep Score with sleep stages, a Readiness score and Cardio Load. Google says it looks for signs of AFib while you're still or sleeping. It lists high and low heart rate alerts and Irregular Rhythm Notifications as Health Guardian features. Display: Google's spec sheet lists no display. You see your data in the Google Health app. Water resistance: Water resistant to 50 m. Google advises drying the band fully after it gets wet or sweaty. Subscription: 3 months of Google Health Premium are included. After that, Premium starts at $9.99, and Google doesn't say whether that's per month or per year. Premium adds a personal coach built with Gemini, adaptive fitness plans, detailed sleep insights, daily guidance and advanced Health Guardian features. It also adds nutrition and cycle-aware coaching, a content library, and workout and mindfulness videos. Activity and sleep tracking, Readiness, Cardio Load and the standard Health Guardian alerts are listed as free app features. If you already pay for Premium, you have to cancel it before the included months can start. You must be over 18 to enroll in Premium. Compatibility: Android 11 or later, or iOS 16.4 or later, with a Google Account and the Google Health app. Connects over Bluetooth 5.0. Google says it's intended for ages 13 and up.	Battery life: Up to 8 days per charge from a 170 mAh lithium-polymer battery, according to Polar. It has 4 weeks of onboard memory. Polar doesn't state a charging time. Sensors: Polar's Precision Prime optical heart rate sensor (OHR Gen 3.5). There's no built-in GPS. Route, pace and distance come from your phone's GPS when you record a session in the Flow app. The page doesn't mention skin temperature, blood oxygen or ECG. Sleep and recovery: Nightly Recharge, Nightly HRV, Sleep Plus Stages, SleepWise and Daily Alertness. Polar says Nightly Recharge combines your sleep score with heart rate, HRV and breathing data to calculate overnight recovery. Activity tracking, Training Load Pro and automatic training detection are also included. Subscription: None. Polar says there are no monthly fees and no locked features. It also offers optional free trials: 60 days of Strava and 30 days of TrainingPeaks Premium. Clue Plus is free for 3 months. Display: None. Polar calls Loop a screen-free band, and you see your data in the Polar Flow app. Water resistance: WR30, which Polar says is suitable for swimming. In the water it tracks heart rate and calories, but not stroke count or distance. Connectivity: Bluetooth LE with one connection, reserved for syncing with Polar Flow. Loop can't act as a heart rate sensor for other devices. Data reaches Strava, TrainingPeaks, Apple Health and Google Health through your Polar Flow account.
Exact variant	Peak membership at $239 a year, including the WHOOP 5.0 device, Wireless PowerPack and SuperKnit band	Classic edition with the Obsidian band, including 3 months of Google Health Premium	Night Black with the SoftWeave Textile band (S–L)
Dimensions	WHOOP doesn't state dimensions or weight on the pages checked. Its launch release says 5.0 and MG pack more technology into a form factor seven percent smaller, without giving measurements.	The tracker is about 34.9 mm long, 17 mm wide and 8.3 mm high (1.4 × 0.7 × 0.3 in). It weighs 5.2 g on its own and 12 g with the band. Google lists the textile and polyurethane band as one size for 130–210 mm wrists.	Polar lists Loop at 1.1 in wide, 1.7 in high and 0.4 in thick. It weighs 1 oz with the band and 0.7 oz without. Polar's size chart says the package includes two bands. The S/M fits 135–190 mm wrists and the M/L fits 160–230 mm.
Installation	No installation. The strap pairs with the WHOOP app, and WHOOP says you can wear it on multiple locations across the body. Your membership starts when you pair and activate the device, or 30 days after the strap ships.	No installation. You need a smartphone, a Google Account and the Google Health app, which runs on Android 11 or later and iOS 16.4 or later. It syncs over Bluetooth 5.0 at up to 30 ft. Syncing also needs an internet connection and location permission on your phone. In the box are the tracker, a wristband and a USB-C charging cable.	No installation. You set it up with the Polar Flow app. The product page doesn't list minimum phone or operating system versions. In the box are the Loop, the SoftWeave bands, a buckle and a Polar Charge 2.0 charging cable. Polar lists the cable as proprietary USB-C. No power adapter is listed.
Materials	Peak comes with a SuperKnit band. The membership comparison table calls it Obsidian, and the page's FAQ calls it Onyx. WHOOP doesn't say what the band fabric or device housing is made of on the pages checked.	Google says the housing is recycled polycarbonate and PBT plastic. The band is textile with a stainless steel buckle, and the Obsidian band's buckle is matte black. The packaging is 100% plastic-free.	Polar lists a stainless steel case and bezel. The band is SoftWeave textile in Night Black. Polar doesn't say what the textile is made of.
Warranty	Lifetime warranty with device replacement, as long as you bought the membership directly through WHOOP and it stays active.	Google's Fitbit Limited Warranty page says Fitbit devices bought on or after July 11, 2023 are covered through the Google Hardware Warranty Center. That center has an option for Fitbit hardware bought since that date, but it doesn't name Fitbit Air or give its warranty length. So the Air's US warranty isn't confirmed. The older Fitbit terms cover new products for one year from purchase. They exclude accidental damage, consumables such as batteries, normal wear and cosmetic damage such as scratches.	Polar Electro, Inc. issues the guarantee for products sold in the US and Canada. It covers the original buyer against defects for two years from the date of purchase. Silicone or plastic wristbands get one year. Textile and leather wristbands aren't covered, so the SoftWeave bands have no guarantee. Normal battery wear, accidents, misuse and cracked or scratched cases are excluded. Polar's returns page says battery replacement is covered for the first six months. Covered products are repaired or replaced, and you'll need the receipt as proof of purchase.
Returns	You can cancel the membership and return the device for any reason within 30 days of receipt. You get a full refund minus the cost of shipping. The membership page doesn't give terms for canceling after 30 days.	Google Store Help says most items can be returned within 15 days of the day you receive them. Before sending it back, you reset the device to factory settings. For a refund, it goes back in its original box with all accessories and documentation. The Fitbit Air page advertises free shipping and returns. The help page doesn't mention restocking fees.	Polar's online store takes returns within 30 days. Items must be unused, in good condition and in the original packaging. You send them with a completed return form and a copy of the packing slip. Shipping costs are refunded only for damaged or defective products. The policy doesn't mention a restocking fee or say how long refunds take. It also doesn't say whether the 30 days start at purchase or delivery.
Unresolved questions	Device dimensions, weight and water resistance rating Sensor types and published accuracy for WHOOP 5.0 specifically Renewal price, auto-renewal terms and what the strap does after the membership ends How WHOOP Age and Pace of Aging are calculated, and whether anyone has independently validated them Shipping cost and cancellation terms after the 30-day return window FDA status of Peak features beyond WHOOP's own statements (FDA databases weren't checked)	The US warranty length for Fitbit Air, since Google's Hardware Warranty Center doesn't name it Premium's billing period, and whether the free months roll into a paid plan Which Health Guardian features count as advanced and need Premium Whether FDA's 2022 clearance of Fitbit Irregular Rhythm Notifications, which lists older devices, covers Fitbit Air Independent accuracy data for Fitbit Air's heart rate, blood oxygen and sleep tracking Test conditions behind the 7-day battery figure Charger power draw and battery lifespan	Charging time and charger power draw Minimum phone and operating system versions for the Polar Flow app What the SoftWeave textile is made of Independent, peer-reviewed accuracy data for Loop's heart rate, HRV and sleep tracking Whether the 30-day return window starts at purchase or delivery How long refunds take

These comparisons use published specifications, not head-to-head tests. Prices and terms are dated. Unknown costs are not zero. Check the exact variant before you buy.