Heart Rate Zone Calculator
Enter your age — or your measured max heart rate — and get your five training zones. Supports both classic % Max HR and the Karvonen (HR Reserve) method when you supply resting HR.
Heart Rate Zone Calculator
Needed for the Karvonen (HR Reserve) method.
| Zone | Purpose | BPM | % Max |
|---|---|---|---|
| Z1 — Recovery | Active recovery, warm-ups, and cool-downs. Very easy effort. | 92–110 | 50–60% |
| Z2 — Easy / Aerobic | Conversational pace. Daily easy runs and long runs live here. Build aerobic base. | 110–129 | 60–70% |
| Z3 — Aerobic | Moderate effort. Marathon pace for most runners. Still controlled breathing. | 129–147 | 70–80% |
| Z4 — Threshold | Comfortably hard. Tempo runs and lactate-threshold work. You can only speak a few words. | 147–166 | 80–90% |
| Z5 — VO₂max | Hard intervals — 3 to 5 minute efforts near your max. Unable to speak. | 166–184 | 90–100% |
Estimates. Your true max HR is best measured via a controlled field test or lab assessment — formulas can miss individual values by 10+ BPM.
Why train by heart rate
Pace and perceived effort are useful, but neither controls for the things that change daily — heat, humidity, terrain, sleep, stress, nutrition. Heart rate is the one metric that actually reflects how hard your body is working right now. Training by HR zones keeps easy days truly easy and hard days truly hard, which is the single most common training mistake amateur runners make.
The five zones, at a glance
- Zone 1 — Recovery (50–60%): very easy. Walking pace. Used for warm-ups, cool-downs, and active recovery.
- Zone 2 — Easy / Aerobic (60–70%): conversational pace. Most of your weekly mileage should live here.
- Zone 3 — Aerobic (70–80%): moderate effort. Roughly marathon pace for most runners. Steady-state runs.
- Zone 4 — Threshold (80–90%): comfortably hard. Tempo runs and lactate-threshold work.
- Zone 5 — VO₂max (90–100%): hard intervals, 3–5 minute efforts. Limited reps, full recovery between.
% Max HR vs Karvonen (HR Reserve)
% Max HRis simple: zone = max HR × percentage. It works but doesn't account for how conditioned your heart is. Two 40-year-old runners with a max of 180 BPM get identical zones — even if one has a resting HR of 45 (very fit) and the other 70 (less fit).
Karvonen (HR Reserve) fixes this by anchoring zones to both your max and your resting HR. The formula is: target HR = resting HR + (max HR − resting HR) × intensity. Because fitter runners have lower resting HRs, Karvonen zones come out higher for them — which matches the reality that their hearts work harder at any absolute BPM.
If you know your resting HR, use Karvonen. If you don't, % Max HR is fine and gives you a reasonable starting point.
Finding your real max HR
Age-based formulas can be off by 10 BPM or more in either direction. If you race hard, the single best source of "real" max HR is the highest value you've seen during the last minute of a competitive 5K or 10K. Note that and plug it in as your measured max.
If you want to formally test, a classic protocol is: warm up for 15 minutes easy, then run as hard as you can for 3 minutes, jog easy for 3 minutes, then run all-out again for 2 minutes. The peak HR at the end of the second hard block is usually within 2–3 BPM of your true max.
Related tools and reading
Pair this calculator with our VDOT calculator for pace-based training zones, or our pace calculator for quick pace math. For a full guide on using heart rate in training, see Heart Rate Training for Runners.
Frequently asked questions
Can I use a chest strap or optical watch for zone training?
Chest straps are more accurate, especially at higher intensities. Optical (wrist) HR is generally fine for easy-moderate work but can lag or drift during intervals. Arm-band optical sensors are a middle ground.
My watch auto-calculates zones. Which is right?
Watches usually use 220 − age by default. If that produces a different max than you've measured, override the watch setting with your measured max. Otherwise, all your zones drift.