Zone 2 should be based on your Max Heart Rate—not your Threshold Heart Rate.
Most people get this wrong.
Even top fitness apps do.
You think you're doing easy cardio…
But if you're using Threshold HR to calculate Zone 2?
You're probably training too hard—and missing the benefits.
Most people think they're doing easy cardio, but their heart rate says otherwise. The problem?
Some popular tools (like COROS) calculate Zone 2 using Threshold Heart Rate instead of HR Max.
That can put you in the wrong zone—literally.
🧠 HR Max vs. Threshold Heart Rate: What’s the Difference?
HR Max (Heart Rate Max) is your highest possible heart rate during intense exertion.
Threshold HR (aka Lactate Threshold) is the point where your body switches from aerobic to anaerobic metabolism.
Threshold HR is usually around 85–90% of your HR Max—so if an app uses it to calculate Zone 2, your target range will be way too high.
❌ Why Some Tools Get It Wrong
Many platforms try to seem "advanced" by using Threshold HR. But here's the problem:
Most people don’t know their real threshold.
Unless you've done a lab test, it's just a guess—often based on flawed running data or race history.
So what feels like “easy cardio” might actually be Zone 3 or 4.
✅ Why HR Max Is the Smarter Approach
Using HR Max is more conservative—but also more correct for most people:
It's science-backed and easier to estimate
It gives you a true aerobic range, where fat burning and mitochondrial gains happen
Zone 2 should feel easy (you can talk in full sentences without gasping)
HR Max-based Zone 2 is usually 10–20 BPM lower than threshold-based methods. That’s a game-changer.
🔢 Try This: Calculate Your HR Max First
Use our Max Heart Rate Calculator to find a solid starting point.
Then plug it into the Zone 2 Heart Rate Calculator, which gives you five different methods to determine your personalized Zone 2 range.
🧪 Bonus Tip: Track Your Resting HR
Want to measure if your training is working?
Watch your resting heart rate drop over time using our Resting Heart Rate Calculator.
It's one of the simplest signs of improved cardio fitness.
🏁 TL;DR
Don’t trust Threshold HR unless you’ve done a real lab test
Use HR Max to calculate a safer, more effective Zone 2
Real Zone 2 feels easy, not “kind of hard”
Use this free calculator to find your personal Zone 2 range