Apple Watch and Samsung Galaxy Watch can both take a single-lead ECG on demand — but that feature is locked to hardware that costs hundreds of dollars either way, and neither works without owning the matching phone ecosystem. AliveCor’s KardiaMobile Card does the same core job — a 30-second single-lead ECG reading you can share with a doctor — as a standalone $79 device that works with any smartphone, watch or no watch. The short version: if you already own a recent Apple Watch or Galaxy Watch, use what you have; if you don’t want to buy a whole new watch just for this, the Card is the cheaper, platform-agnostic way in.
Who Actually Needs a Personal ECG Device?
This isn’t a general-fitness feature — it’s specifically useful for people managing or screening for atrial fibrillation (AFib) and other rhythm irregularities, especially anyone who’s had an episode, has a family history, or has been told by a doctor to log symptomatic episodes. If that’s not you, a passive heart-rate sensor on any basic fitness tracker covers typical day-to-day needs, and none of the three devices here are worth buying purely for general wellness tracking.
Apple Watch: ECG App Built Into Watch Hardware
Apple’s ECG app has been available since Apple Watch Series 4 in 2018 and remains one of the earliest FDA-cleared consumer ECG features. Placing a finger on the Digital Crown for 30 seconds records a single-lead (Lead I) ECG and classifies the rhythm as sinus rhythm, AFib, or inconclusive, storing a PDF you can share directly with a doctor. It’s included at no extra cost on every compatible watch — no subscription, no per-reading fee — but it only works on Apple Watch Series 4 and later, meaning the feature itself is free while the entry ticket is a watch that starts around $399.
Apple also runs a separate, passive AFib History feature that estimates how often your heart shows signs of AFib over time, distinct from the on-demand ECG app — the two work together but measure different things: one is a snapshot you take yourself, the other is ongoing background estimation.
Samsung Galaxy Watch: Two Separate Heart Rhythm Tools
Samsung’s approach splits into two features that are easy to conflate. The first is an on-demand ECG app in Samsung Health Monitor, functionally similar to Apple’s — a single-lead reading taken by touching the watch’s frame. The second is the Irregular Heart Rhythm Notification (IHRN), a separate, passive background feature that checks for AFib-suggestive patterns via the watch’s BioActive Sensor without you doing anything. Samsung’s own announcement is explicit that IHRN “is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib” and doesn’t replace a doctor.
IHRN’s current FDA clearance covers Galaxy Watch4 series and later, and it rolled out alongside the ECG app rather than replacing it. Like Apple’s setup, both Galaxy Watch heart-rhythm features are included free with the hardware — the cost barrier is the watch itself, which starts at $299.99 for the current Galaxy Watch8.
KardiaMobile Card: A Standalone ECG That Skips the Watch Entirely
AliveCor’s KardiaMobile Card is a different category of product: a credit-card-sized, single-lead (Lead I) EKG device that connects to any smartphone via an audio-based connection rather than Bluetooth, at $79 direct from Kardia. Free, it detects AFib, bradycardia, tachycardia, and normal sinus rhythm from a 30-second reading — the same core categories as either watch’s ECG app, without requiring you to own a specific brand of phone or a several-hundred-dollar watch at all.
A paid KardiaCare membership, priced around $99/year based on current third-party device comparisons (AliveCor doesn’t publish the figure prominently on its own product pages, so treat this as an estimate to confirm before buying), adds three more rhythm classifications — sinus rhythm with wide QRS, sinus rhythm with PVCs, and sinus rhythm with SVE — on top of the four free categories. A higher KardiaCare Plus tier, around $299/year by the same third-party reporting, adds a cardiologist teleconference review of your ECG. Neither membership is required to use the core device or send readings to your own doctor.
What It Actually Costs to Get a Real ECG Reading
This is the number that matters and doesn’t show up on any single product page: the true entry cost of each option, once you account for whether you already own the required hardware.
| Apple Watch ECG | Galaxy Watch ECG + IHRN | KardiaMobile Card | |
|---|---|---|---|
| Feature cost itself | Free (built in) | Free (built in) | Free (basic 4-category detection) |
| Required hardware if you don’t already own it | Apple Watch Series 4+, from ~$399 | Galaxy Watch4+, from $299.99 | Just the Card itself, $79 |
| Works with | iPhone only | Android (Samsung-optimized) | Any iOS or Android phone |
| Optional paid tier | None | None | ~$99/yr (KardiaCare) or ~$299/yr (Plus, with cardiologist review) |
| Cheapest way to a first reading if starting from zero | ~$399 | ~$299.99 | $79 |
Prices reflect current manufacturer and retailer listings as of publication and change frequently — confirm the latest price with the retailer before buying.
So Which One Should You Actually Get?
If you already own a compatible Apple Watch or Galaxy Watch, there’s no reason to buy anything else — the ECG feature is already sitting on your wrist for free, and both are legitimately FDA-cleared for what they do. Between the two watches, Apple’s ECG app has the longer track record, while Samsung’s setup uniquely pairs an on-demand reading with a passive background notification in one device.
If you don’t already own either watch and the ECG feature is your main reason for buying one, the math changes: a $399+ or $299.99+ watch purchase is a steep price for a feature the $79 KardiaMobile Card performs on hardware you already have. The Card is also the only option here that doesn’t lock you into one phone ecosystem, which matters if you’re choosing on behalf of a parent or family member whose phone you don’t control.
How We Researched This Comparison
We did not use any of these three devices ourselves for this comparison. Facts and pricing were verified against each manufacturer’s own current product and clearance documentation — Apple’s and Samsung’s own newsroom announcements, and AliveCor/Kardia’s own device-comparison page — with the KardiaCare membership price specifically flagged above as third-party-reported rather than confirmed on AliveCor’s own site. See our editorial standards page for more on our process. Prices are approximate, current as of publication, and change frequently — confirm the latest price with the retailer before buying.
Frequently Asked Questions
Is the Apple Watch ECG app the same as a full 12-lead EKG at a hospital?
No. It’s a single-lead (Lead I) ECG, a much narrower snapshot than a clinical 12-lead EKG. It’s useful for catching signs of AFib and sharing a reading with a doctor, not for a full cardiac workup.
Do I need a Galaxy Watch for the Irregular Heart Rhythm Notification to work?
Yes — IHRN currently requires a Galaxy Watch4 or later, per Samsung’s own FDA clearance documentation, and works via the watch’s BioActive Sensor rather than through a phone alone.
Can the KardiaMobile Card replace a smartwatch’s ECG feature?
For the core job of taking a single-lead ECG reading, yes — it detects the same four basic categories (AFib, bradycardia, tachycardia, normal) as either watch’s app, at a fraction of the cost, though it doesn’t do anything else a smartwatch does.
Do I need a subscription to use any of these?
No. Apple’s ECG app and Samsung’s ECG/IHRN features are both included free with a compatible watch. The KardiaMobile Card’s core four-category detection is also free — a paid KardiaCare membership is optional and only adds extra rhythm classifications and, at the higher tier, a cardiologist review.
Are any of these three devices a substitute for seeing a cardiologist?
No. All three manufacturers frame their devices as screening and logging tools meant to inform a conversation with a doctor, not to diagnose heart conditions on their own. Talk to a healthcare provider about any symptoms or irregular readings.
Curious about blood pressure claims on the same watches? Our smartwatch blood pressure comparison covers a related — and often confused — set of health claims. For ring-based alternatives, see our smart ring comparison. Browse more comparisons in our Wearable Tech category.
