What Are Heart Rate Zones?
If you've ever finished a workout wondering whether you pushed hard enough, or maybe too hard, you're not alone. Most beginners have no real gauge for effort. You go by feel, by sweat, by how out of breath you are. And those things matter, but they're imprecise.
Heart rate zones are ranges of exercise intensity measured in beats per minute (bpm). Each zone corresponds to a different level of physical effort, and each one produces a different effect in your body.
Most exercise scientists use a five-zone model, where Zone 1 is the easiest (a light walk, essentially) and Zone 5 is absolute maximum effort. The idea is that you don't need to be gasping for air every time you work out. Different zones build different things: aerobic base, fat-burning capacity, cardiovascular endurance, speed, and a smart training approach uses all of them.
For beginners, zones give you structure. Instead of just "going to the gym," you can say: today I'm staying in Zone 2 for 40 minutes. That specificity leads to better results and less burnout.
Why the Karvonen Formula Beats the Simpler Method
You may have seen the old "220 minus your age" formula. It gives you an estimated maximum heart rate, and then you multiply that by a percentage to get a zone target. Simple enough, but it has a flaw.
It doesn't account for your resting heart rate.
Two people who are both 35 years old could have resting heart rates of 50 bpm and 75 bpm respectively. Their cardiovascular systems are in completely different places, one likely much fitter than the other. Yet the basic formula would assign them identical zones.
The Karvonen formula fixes this. It uses your heart rate reserve (HRR), the gap between your resting and maximum heart rate, to calculate zones that reflect where you actually are, fitness-wise. The American College of Sports Medicine (ACSM) recommends this approach for exercise prescription because of that personalization.
How to Calculate Your Heart Rate Zones (Step by Step)
Before you do the math, you need two numbers:
Your resting heart rate (RHR): Measure this first thing in the morning, before you get out of bed. Count the beats for 60 seconds, or count for 15 seconds and multiply by four. A typical adult RHR is between 60–80 bpm; well-conditioned people are often below 60.
Your maximum heart rate (MHR): The most common estimate is 220 minus your age. It's not perfect, but it's a solid starting point. For more accuracy, a graded exercise test at a sports medicine clinic is the gold standard, but not necessary when you're just getting started.
The Karvonen formula:
Target HR = ((Max HR − Resting HR) × % Intensity) + Resting HR
First, calculate your Heart Rate Reserve:
HRR = Max HR − Resting HR
Then apply the intensity percentage for each zone:
| Zone | Name | % of HRR | What It Feels Like |
|---|---|---|---|
| Zone 1 | Recovery | 50–60% | Easy conversation, no real effort |
| Zone 2 | Fat Burn | 60–70% | Can still talk, mild breathing increase |
| Zone 3 | Aerobic | 70–80% | Harder to hold a full conversation |
| Zone 4 | Threshold | 80–90% | Short sentences only; uncomfortable |
| Zone 5 | Max Effort | 90–100% | Can't speak; unsustainable for long |
Worked example: 35-year-old, resting HR of 65 bpm
Max HR: 220 − 35 = 185 bpm
HRR: 185 − 65 = 120 bpm
Zone 2 lower bound: (120 × 0.60) + 65 = 137 bpm
Zone 2 upper bound: (120 × 0.70) + 65 = 149 bpm
The 5 Zones: What Each One Does for You
Zone 1: Recovery (50–60% HRR)
This is gentle movement: a slow walk, light stretching, easy cycling. You can hold a full conversation with no trouble at all. Zone 1 isn't about burning calories; it's about keeping your body moving on rest days and flushing out muscle soreness. Beginners benefit from spending time here as their bodies adjust to regular activity.
Zone 2: Fat Burn (60–70% HRR)
Zone 2 is where most beginners should spend the majority of their cardio time. At this intensity, your body predominantly burns fat as its fuel source. It's sustainable for long periods, builds your aerobic base, and trains your cardiovascular system without overloading it. If you're targeting weight loss, this is your zone. Read more about exactly how this works in our article on the fat-burning heart rate zone.
Zone 3: Aerobic (70–80% HRR)
Breathing picks up noticeably here. Zone 3 improves your overall cardiovascular fitness and your body's ability to sustain moderate-to-hard effort. Brisk jogging, a fast walk on an incline, or cycling at a pace that challenges you would land most beginners in Zone 3.
Zone 4: Threshold (80–90% HRR)
This is hard. You're pushing into uncomfortable territory, and your muscles are producing lactic acid faster than your body can clear it. Short sentences are about all you can manage. Zone 4 training raises your lactate threshold, the point at which your body starts to fatigue rapidly, which is valuable for fitness progress, but beginners shouldn't live here. Occasional Zone 4 work is great; too much leads to burnout or injury.
Zone 5: Maximum Effort (90–100% HRR)
All-out sprints. HIIT intervals. Total exertion. Zone 5 can only be sustained for very short bursts, usually 30 seconds to a couple of minutes, and it's not where most beginners need to spend time. As your fitness develops, Zone 5 work can be added sparingly to build speed and peak power.
Which Zone Should Beginners Focus On?
For most beginners, the answer is Zone 2 the vast majority of the time, roughly 80% of workouts, with occasional ventures into Zone 3. This mirrors what exercise physiologists call the 80/20 principle: most of your training at lower intensity, a smaller portion at higher intensity.
The temptation for beginners is to go too hard, too soon. Every workout becomes a struggle. But training too often at high intensity without the aerobic base to support it is a fast track to exhaustion and injury.
Zone 2 is more effective than it looks. It builds the cardiovascular foundation that makes everything else possible, including eventually working out harder, for longer, with less effort. For a deeper look at structuring Zone 2 sessions, see our Zone 2 training guide.
How to Measure Your Heart Rate During Exercise
You don't need expensive equipment. A few options:
Chest strap monitor (Polar, Garmin): Most accurate. Research consistently shows chest straps match clinical-grade monitoring for steady-state cardio.
Smartwatch / fitness tracker (Apple Watch, Garmin, Fitbit): Reasonably accurate for steady-state activity like walking, running, and cycling. Less reliable during high-movement exercises or rapid intensity changes.
Manual pulse check: Press two fingers to your wrist or neck, count beats for 15 seconds, multiply by four. Less convenient during exercise but works fine for spot-checking at rest or during low-intensity activity.
Frequently Asked Questions
How often should I check my resting heart rate?
Once a week is plenty once you have a baseline. Measure it on the same day each week, first thing in the morning. Over time, a declining resting HR is one of the clearest signs your fitness is improving.
My heart rate jumps above my zone during workouts. Is that okay?
Completely normal for beginners. Your cardiovascular system is adapting. Slow down a little, let your rate drop into range, and build gradually. Don't force a pace that keeps you above zone.
Do my zones change as I get fitter?
Yes. As your resting heart rate drops with improved fitness, your Karvonen-calculated zones shift slightly. Recalculate every few months to keep your targets accurate.
Can I use these zones for any type of exercise?
Generally yes: running, cycling, swimming, and cardio machines. Note that heart rate zones tend to run slightly lower for cycling than running, because running engages more muscle mass.
The math isn't hard, but there's no reason to do it by hand. Head to CalculateMyHeartRate.com, enter your age and resting heart rate, and your five Karvonen zones will be ready in seconds. Your zones are personal to you; use them that way.
This article is for informational purposes only and does not constitute medical advice. Please consult a physician or certified fitness professional before starting a new exercise program.