Heart-rate zones translate vague "easy/hard" into specific bpm windows that match your physiology. This tutorial gives you the cleanest path: compute max heart rate, optionally personalise with resting heart rate, and read off your five zones.
Quick Answer
Two pieces of math, plus optional cleanup:
- Max HR (Tanaka):
HRmax = 208 − 0.7 × age - Zones:
- Without resting HR: each zone is a percentage of HRmax
- With resting HR (more personalised): Karvonen uses heart-rate reserve (HRR)
Run them in seconds with our Heart Rate Zone Calculator.
Step 1: Calculate Max Heart Rate
The old rule 220 − age over-estimates HRmax for young adults and under-estimates for older ones. The Tanaka equation is the modern replacement:
HRmax = 208 − 0.7 × age
Age 30 → 208 − 21 = 187 bpm Age 50 → 208 − 35 = 173 bpm
Both formulas are population averages. Individual HRmax can sit 5–10 bpm higher or lower; a properly conducted max-effort test on a treadmill or bike is more accurate than any formula.
Step 2: Decide on a Method
Two choices once HRmax is set.
Method A: Percentage of HRmax
Each zone is a band of HRmax:
| Zone | % HRmax | |---|---| | Z1 — Recovery | 50–60% | | Z2 — Endurance | 60–70% | | Z3 — Aerobic | 70–80% | | Z4 — Threshold | 80–90% | | Z5 — Max | 90–100% |
Simple, no resting HR required.
Method B: Karvonen (Heart Rate Reserve)
Uses HRR = HRmax − HRrest:
Target HR = HRR × intensity + HRrest
Karvonen is more personal: fitter people have lower resting HR, wider HRR, and slightly different absolute zone bpm.
Step 3: Measure Resting HR (Optional but Recommended)
For the Karvonen method:
- First thing in the morning, before getting out of bed
- Count pulse for 60 seconds (more accurate than 15 × 4)
- Repeat for 3 mornings, average
A typical RHR for adults is 60–80 bpm; well-trained endurance athletes often run 40–55.
Worked Example — Age 30, RHR 60
HRmax = 187. HRR = 187 − 60 = 127.
| Zone | Karvonen formula | Range | |---|---|---| | Z1 | (127 × 0.50–0.60) + 60 | 124–136 bpm | | Z2 | (127 × 0.60–0.70) + 60 | 136–149 bpm | | Z3 | (127 × 0.70–0.80) + 60 | 149–162 bpm | | Z4 | (127 × 0.80–0.90) + 60 | 162–174 bpm | | Z5 | (127 × 0.90–1.00) + 60 | 174–187 bpm |
Same person without RHR (Method A) would see different absolute bpms — Karvonen tends to pull the numbers upward for fit individuals, downward for less fit.
Step 4: Apply Zones to Training
Once you have your zones, the practical rule is polarised distribution:
- 70–80% of weekly cardio volume in Zones 1–2 (easy aerobic)
- 10–15% in Zone 3 (steady tempo)
- 10–20% in Zones 4–5 (hard intervals)
The biggest amateur mistake is too much Zone 3 — feels productive, hard to recover from, lower per-minute aerobic return.
Step 5: Track and Re-test
Re-check zones every 8–12 weeks, especially if:
- You're significantly fitter (RHR drops 5+ bpm)
- You've changed sports (cycling and running have different HRmax)
- Body weight has changed meaningfully
A simple field re-test: a 20-minute time trial at all-out effort. Average HR is roughly your threshold HR. Anchoring zones from a measured threshold is more precise than the formula.
Field-Testing Your Personal Maximum
Formulas give you the population average. Your real HRmax can be 10 bpm above or below, and finding the personal number turns generic zones into personal ones. Two tested protocols:
For runners — the 5-minute hill repeat test:
- Warm up for 15 minutes easy.
- Find a steep hill (~5–8% grade) that takes about 2 minutes to climb hard.
- Run it three times, each time pushing harder; recover fully between (3 minutes walk).
- On the third repeat, sprint the final 30 seconds. The peak HR on this rep is within 2–3 bpm of your true HRmax.
For cyclists — the indoor ramp test:
- Warm up 10 minutes at 80 W or easy spin.
- Increase power by 25 W every minute.
- Hold each level until cadence collapses.
- The peak HR at exhaustion is your max.
Re-test once every 12–18 months. HRmax declines slowly (1 bpm per year on average), so frequent re-testing isn't necessary.
Why Heart Rate Lags Effort
A common frustration: you increase your pace, but the watch doesn't catch up for 30–60 seconds. That delay is normal physiology.
- Cardiac lag: the heart takes 20–40 seconds to fully accelerate to a new workload.
- Sensor lag: add another 5–15 seconds of smoothing in the watch firmware.
- Cardiac drift: at sustained sub-threshold effort, HR slowly rises over 30+ minutes at the same pace, often by 10+ bpm. The body recruits more reserve as fluid and glycogen deplete.
- Recovery lag: after stopping a hard interval, HR drops fast at first (~30 bpm in the first minute) then slows; fully resting HR can take 5–10 minutes.
The practical fix: for interval sessions, time the work-rest by the watch, not by HR. For steady efforts, give HR 1–2 minutes to settle before judging the zone.
Choosing the Right Zone for the Workout
| Goal | Zone | Effort feel | |---|---|---| | Active recovery | Z1 | Very easy, "could go forever" | | Long aerobic base | Z2 | Conversational | | Tempo run / bike | Z3 | Comfortably hard, talk only in clipped phrases | | Threshold intervals | Z4 | Hard, race-pace effort | | VO₂max intervals | Z5 | All-out, can't talk |
If pace pushes HR above your planned zone on an easy day, slow down. The zone is the plan; the pace is the result.
Common Mistakes
- Using
220 − age. Tanaka is more accurate. - Comparing zones across sports. Cycling HRmax is typically 5–10 bpm lower than running for the same person.
- Optical wrist sensors during intervals. Wrist-based HR drifts at intensity; chest straps are noticeably better for true zone work.
- Treating zones as fixed numbers forever. Fitness changes; re-test.
- Forgetting cardiac drift. Long sessions push HR up at the same pace; that's normal.
Frequently Asked Questions
Do I need a chest strap?
For everyday Z1–Z2 work, wrist sensors are fine. For intervals and threshold work, chest straps are noticeably more accurate.
Why does my HR run high in heat?
Hot conditions raise HR 10–20 bpm at the same workload. Hold the zone (not the pace) and you'll train correctly without overcooking.
Is Karvonen always better than %HRmax?
For fit individuals with low RHR, yes — Karvonen produces more personal bpm ranges. For sedentary or untested adults, %HRmax is often a fine starting point.
My max HR seems higher than the formula predicts. Should I use the higher number?
Yes, if you've tested it under controlled conditions. Personal best HR from a max effort is more accurate than any formula.
How long does it take to see Zone 2 pace improve?
With consistent base work, your Z2 pace at the same HR typically improves within 4–6 weeks. Threshold pace gains take 8–12 weeks of structured Z3–Z4 work.
Bottom Line
Heart-rate zones turn cardio from a guess into a plan:
- Compute HRmax with Tanaka in our Heart Rate Zone Calculator.
- Optionally add resting HR for personalised Karvonen zones.
- Match workouts to zones — most volume in Z1–Z2, hard work measured in Z4–Z5.
- Re-test every 8–12 weeks, especially as RHR drops.
The fitness gains follow the zones; the zones follow the math.
Health and fitness calculations are estimates only and not medical advice. If you take heart-rate-altering medication (e.g., beta-blockers), or have a heart condition, consult a doctor before training by zones.