Train smarter, not just harder
Knowing the right intensity is the difference between a workout that moves you forward and one that just tires you out. Heart rate zones translate the vague advice of “work hard” into precise numbers your body understands — and once you know your zones, every session has a purpose.
This free calculator takes your age — and optionally your resting heart rate for a more personal result — and instantly shows your estimated maximum heart rate plus all five training zones, so you can see exactly how hard to push for fat loss, cardio fitness, or peak performance.
| Zone | Target Range | % of Max | Purpose |
|---|
*The American Heart Association recommends exercising at 50–85% of your maximum heart rate. These estimates are for general guidance only — consult a healthcare professional before starting an exercise program, especially if you have a heart condition.
How to Use This Calculator
- Choose your method. Pick “Standard (220 − Age)” for a quick estimate, or “Karvonen (with Resting HR)” for a personalized result that accounts for your fitness level.
- Enter your age. Type your age or drag the slider — the zones update as you type.
- Enter your resting heart rate (Karvonen only). Measure your pulse first thing in the morning, before you get out of bed, for the most accurate number.
- Click “Calculate My Heart Rate Zones.” You will see your estimated max heart rate, a visual intensity bar, and a complete table of all five zones with their bpm ranges and purposes.
- Read your zones. The stat boxes below the table highlight your fat-burn zone and the moderate target range recommended by the American Heart Association.
What Are Heart Rate Zones?
Heart rate zones are intensity ranges, expressed as percentages of your maximum heart rate, that describe how hard your heart is working during exercise. Trainers and sports scientists divide effort into five zones, each using your body in a slightly different way:
| Zone | Intensity (% of max) | What it’s for |
|---|---|---|
| Zone 1 — Recovery | 50–60% | Gentle movement: easy walking, warm-ups and cool-downs |
| Zone 2 — Fat Burn | 60–70% | Endurance sweet spot; fat supplies a large share of the energy |
| Zone 3 — Aerobic | 70–80% | Heart and lungs adapt here; cardiovascular fitness builds fastest |
| Zone 4 — Anaerobic | 80–90% | Hard intervals; builds speed, power, and lactate tolerance |
| Zone 5 — Maximum | 90–100% | All-out sprints; short bursts for experienced athletes only |
The point of zone training is simple: instead of guessing how hard you are working, you train at the intensity that matches your goal. Want to lose weight without exhausting yourself? Spend most of your time in Zone 2. Training for a race? You will need structured time in Zones 3 and 4.
The Formula + Worked Example
Two formulas power this calculator, and understanding them helps you trust the numbers.
Karvonen: Target HR = Resting HR + (Heart Rate Reserve × Zone %), where HRR = Max HR − Resting HR
Worked example (Standard): A 35-year-old estimates max HR = 220 − 35 = 185 bpm. Zone 2 (60–70%) = 185 × 0.60 = 111 to 185 × 0.70 = 129.5, or about 111–130 bpm.
Worked example (Karvonen): The same 35-year-old with a resting heart rate of 62 bpm. Heart rate reserve = 185 − 62 = 123 bpm. Zone 2 = 62 + (123 × 0.60) ≈ 136 bpm to 62 + (123 × 0.70) ≈ 148 bpm — about 136–148 bpm. Notice the Karvonen zone runs higher, because this person’s low resting heart rate tells the formula they are reasonably fit.
Why Karvonen Numbers Look Higher Than the Gym Chart
The gym wall chart uses only your maximum heart rate. Karvonen starts from a simple insight: your heart is already beating at your resting rate, so the range you actually control is the reserve between resting and maximum. Building zones on that reserve pushes every zone upward. For a 40-year-old with a resting heart rate of 60 (max 180, reserve 120):
| Zone | Karvonen range |
|---|---|
| Zone 1 — Recovery | 120–132 bpm |
| Zone 2 — Fat Burn | 132–144 bpm |
| Zone 3 — Aerobic | 144–156 bpm |
| Zone 4 — Anaerobic | 156–168 bpm |
| Zone 5 — Maximum | 168–180 bpm |
Compare Zone 2: the standard method gives 108–126 bpm for the same person, while Karvonen gives 132–144. Neither is wrong — Karvonen simply credits your fitness (a lower resting rate means a bigger reserve) and asks more of you. Cross-check the effort with the talk test below, and see the fitness side of the same picture with our VO2 Max Calculator.
Which Zone Should You Train In?
- Weight loss and general health: live in Zones 1–2. Long Zone 2 sessions burn a high proportion of fat and are easy to recover from, so you can do them often.
- Building cardio fitness: add Zone 3. A weekly tempo session here steadily raises the effort you can sustain.
- Race performance and speed: include Zone 4 intervals. This is where your body learns to clear lactate and hold a faster pace.
- Zone 5: use sparingly — short intervals, full recovery between them, and only once you have a solid base.
Endurance research keeps returning to the same pattern: roughly 80% of training time in easy zones, 20% hard. The athletes who follow it get faster; the ones who spend every session in the middle grind themselves down. If your heart rate has been hovering in Zone 3 all week, you are probably training harder than your plan thinks — a common beginner mistake called “grey zone” training.
The talk test is the no-equipment cross-check: in Zones 1–2 you can speak in full sentences; in Zone 3, only short phrases; in Zone 4, a few words at a time; in Zone 5, talking is basically impossible. If your speech and your zone disagree, trust your speech — and pace the session with our Running Pace Calculator.
Limitations of Heart Rate Zone Calculators
- 220 − Age is a population average. Real maximum heart rates vary widely between individuals — that’s why your fitness watch may disagree with the calculator. Use the numbers as guidance and adjust by how you actually feel.
- Zones shift with conditions. Heat, dehydration, illness, poor sleep, caffeine, and altitude all raise heart rate for the same effort. On those days, slow down regardless of what the zone says.
- Medication changes everything. Beta-blockers and other heart-rate-affecting drugs lower your pulse and make these estimates unreliable — ask your doctor for personal target ranges instead.
- Formula choice matters with age. The Tanaka formula (208 − 0.7 × age) often fits older adults better than 220 − age: at age 60 it estimates a maximum of 166 bpm versus 160 bpm.
- Perceived effort still matters. A number on the screen beats “go hard” as coaching advice, but it doesn’t replace listening to your body.
Tips for Training by Heart Rate
- Measure resting heart rate properly: first thing in the morning, before coffee, while still lying down. It is the anchor of the Karvonen method.
- Warm up and cool down: five to ten minutes in Zone 1 on both ends protects your heart and improves recovery.
- Get a heart rate monitor. Wrist sensors are convenient, but a chest strap is noticeably more accurate during intervals.
- Recalculate as you improve. When your resting heart rate drops — and it will — your zones shift. Recheck every couple of months.