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Fitness band

WHOOP MG

Life membership at $359 a year, including the WHOOP MG device, Wireless PowerPack and a choice of band

$359 a yearUS price, checked Oct 26, 2026

Display-free strap with an FDA-cleared ECG, sold only inside the Life membership

Check price at WHOOP Full review →

Fitness band

Polar Loop

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

$199.99US price, checked Oct 23, 2026

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

Check price at Polar Full review →

Criterion	WHOOP MG	Polar Loop
US price	$359 a yearChecked Oct 26, 2026 · Price details in the review	$199.99Checked Oct 23, 2026 · Price details in the review
Three-year ownership estimate	$1,077 Incomplete known subtotal. Not included: energy use.	$199.99 Incomplete known subtotal. Not included: energy use.
Choose if	You want an FDA-cleared ECG on a screen-free strap and don't mind paying $359 a year for the membership that includes it.	You want nightly recovery and sleep scores from a band with no screen and no monthly fee.
Main trade-off	It costs $1,077 over three years, and its Blood Pressure Insights is a beta wellness estimate with no FDA clearance.	You need your phone for GPS, and Polar lists no skin temperature or blood oxygen sensing.
Key specifications	Membership cost: $359 a year for Life, the only tier that includes the MG. Peak is $239 a year and One is $199 a year, both with a WHOOP 5.0 device. WHOOP's membership pages list yearly prices only. Memberships renew at WHOOP's then-current price until you cancel. What Life includes: The MG device, a Wireless PowerPack and a choice of band. It also includes everything in Peak: Healthspan with WHOOP Age, Pace of Aging, Health Monitor alerts and a real-time Stress Monitor. On top of that come Heart Screener with ECG, on-demand AFib detection and Blood Pressure Insights. Battery and charging: 14+ days per charge. A full charge takes about 2 hours. The Wireless PowerPack slides onto the sensor 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. The join page calls the PowerPack that comes with Life waterproof. Display and GPS: No display or built-in GPS. You read your data in the WHOOP app. Sensors: WHOOP says its sensors capture data 26 times per second. The FDA's summary says the ECG reads from electrodes on the strap. WHOOP's launch release says you touch the ECG-conductive clasp to take a reading. Its heart health page says light sensors read your PPG pulse waveform overnight. ECG (Heart Screener): The FDA cleared the WHOOP ECG feature on April 4, 2025 (510(k) K243236) for adults 22 and older. It classifies a 30-second recording as AFib, normal sinus rhythm, low heart rate, high heart rate, inconclusive or unsuccessful. WHOOP says it isn't for people with known arrhythmias other than AFib, and isn't recommended with a pacemaker or ICD. It isn't available in every region. ECG study results: The study behind the clearance had about 540 subjects with a mean age of 60.4. The feature had 96.2% sensitivity for AFib and 99.4% specificity for sinus rhythm on classifiable recordings. The reference was a cardiologist's reading of a simultaneous 12-lead ECG. The feature called 11% of recordings inconclusive. Blood Pressure Insights: A daily systolic and diastolic range, estimated once a day from overnight sensor data. WHOOP calls it a beta feature for wellness and says it is not a medical device. You calibrate it with cuff readings you log in the app. WHOOP says your true value may be higher or lower than the range shown. It also says the feature isn't intended for use if you are pregnant or on blood pressure medication. FDA status of Blood Pressure Insights: No clearance is listed. The FDA's 510(k) records under WHOOP's name show only the ECG feature. In July 2025 the FDA told WHOOP it was marketing Blood Pressure Insights without clearance or approval. In June 2026 the FDA closed that warning letter, saying it doesn't intend to enforce device requirements for the feature as modified. The close-out letter doesn't say the feature is cleared, approved or validated. Trial and trade up: The one-month free trial uses a certified pre-owned WHOOP 5.0 device on Peak, not an MG. WHOOP says free trials of Life aren't available. Trading in an eligible Oura Ring, Apple Watch, Garmin or Samsung watch takes up to $119 off the first year, and a Fitbit is worth $30. You have 30 days to ship the old device and charger. If you don't, WHOOP may suspend the membership or charge you the discount. Upgrading to MG: Current members can move up to Life at any time and get a new MG device. WHOOP's membership page says you pay a prorated amount. Its terms also describe a membership extension or a one-time upgrade fee, and give no amount for the fee.	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	Life membership at $359 a year, including the WHOOP MG device, Wireless PowerPack and a choice of band	Night Black with the SoftWeave Textile band (S–L)
Dimensions	WHOOP doesn't state dimensions, weight or water resistance for the MG 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.	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. For the ECG, WHOOP's launch release says you place your thumb and index finger on the ECG-conductive clasp. If you buy from WHOOP, your membership starts when you connect the device or 30 days after delivery, whichever comes first. The pages checked don't say which bands have the conductive clasp.	No installation. You set it up with the Polar Flow app, and Polar's page gives no minimum phone or operating system versions. The box holds the Loop, the SoftWeave bands, a buckle and a Polar Charge 2.0 cable, which is proprietary USB-C. Polar's package list doesn't include a power adapter.
Materials	WHOOP doesn't say what the MG's housing is made of on the pages checked. Its membership FAQs name the Life band as a Titanium SuperKnit Luxe band but don't list band materials. The join page says Life comes with your choice of 6 included bands, and it lists 10 more band colors. The launch release mentions an ECG-conductive clasp but doesn't name its material.	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, for as long as your membership is active and paid up. WHOOP's terms cover defects in materials or workmanship. You need a valid payment method on file and a device bought from WHOOP or an authorized reseller. The terms exclude lost devices, including lost chargers or PowerPacks. They also exclude misuse, normal wear and tear, accidents, theft and cosmetic damage. WHOOP may repair or replace the device, or refund the device share of the membership price. You may pay shipping and handling for the replacement. The warranty can't be transferred.	Polar gives a two-year guarantee on the device, but not on the SoftWeave bands. Polar Electro, Inc. issues it for products sold in the US and Canada, covers the original buyer against defects, and asks for the receipt as proof of purchase. Silicone or plastic wristbands get one year, and textile and leather wristbands aren't covered. 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, and Polar repairs or replaces covered products.
Returns	You have 30 days from receipt to cancel and return the device for a full refund of the initial membership fee, less return shipping. You contact WHOOP support for a return label, and the device has to arrive within 30 days of your request. After 30 days WHOOP refunds nothing. Canceling later ends the membership at the end of the current term, with no prorated refund. The 30-day policy doesn't apply to free trials. Once you request a return, you can't use the account tied to that device. Reseller purchases follow the reseller's return policy. A wearable you trade in can't be returned, even if you cancel in the first 30 days.	Polar's online store takes returns within 30 days, and damaged or defective items within 30 days of purchase. 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, and it doesn't say whether a standard return counts from purchase or delivery.
Unresolved questions	MG dimensions, weight and water resistance rating Which bands have the ECG-conductive clasp Whether WHOOP's Irregular Heart Rhythm Notifications are FDA-authorized, since the FDA 510(k) search under WHOOP's name lists only the ECG feature Independent accuracy data for the MG's sleep, heart rate and Blood Pressure Insights Error figures for Blood Pressure Insights, and what WHOOP changed to get the FDA close-out Renewal price after year one, shipping cost, and what the strap does after the membership ends The amount of the one-time upgrade fee for current members	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 window for a standard return 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.