Calculate Zone 4 (cardio, 80–90% HRmax) and Zone 5 (peak, 90–100% HRmax). Use these high-intensity zones to build VO₂ max, lactate threshold, and anaerobic power.
Zone 4 (cardio/threshold) is 80–90% of estimated maximum heart rate and Zone 5 (peak) is 90–100%. For a 40-year-old man (estimated HRmax ≈ 180 bpm, Tanaka) that is about 144–162 bpm for Zone 4 and 162–180 bpm for Zone 5. For a 40-year-old woman (estimated HRmax ≈ 171 bpm, Gulati) it is about 137–154 bpm and 154–171 bpm.
| Age | Est. HRmax, men (Tanaka) | Zone 4 (threshold) bpm, men | Est. HRmax, women (Gulati) | Zone 4 (threshold) bpm, women |
|---|---|---|---|---|
| 20 | 194 | 155–175 | 188 | 150–169 |
| 25 | 191 | 153–172 | 184 | 147–166 |
| 30 | 187 | 150–168 | 180 | 144–162 |
| 35 | 184 | 147–166 | 175 | 140–158 |
| 40 | 180 | 144–162 | 171 | 137–154 |
| 45 | 177 | 142–159 | 166 | 133–149 |
| 50 | 173 | 138–156 | 162 | 130–146 |
| 55 | 170 | 136–153 | 158 | 126–142 |
| 60 | 166 | 133–149 | 153 | 122–138 |
| 65 | 163 | 130–147 | 149 | 119–134 |
| 70 | 159 | 127–143 | 144 | 115–130 |
Why the men's and women's columns differ: the zone percentages are identical for both — 60–70% of HRmax is Zone 2 regardless of sex. Only the equation used to estimate HRmax differs: Tanaka (208 − 0.7 × age) is used for men and Gulati (206 − 0.88 × age), derived from a study of 5,437 women, is used for women. Because Gulati declines faster with age, the two estimates are close in the twenties and diverge by roughly 10 bpm by age 60. That gap reflects the study population each equation came from, not a different physiological zone model — and individual variation (±10–12 bpm) is larger than the difference between the formulas.
How to read these numbers: they are estimated maximum heart rates from age-based equations, not measured maximums. Individual HRmax varies by roughly ±10–12 bpm around any age prediction, so treat the bands as a starting range and adjust using perceived effort or a supervised maximum-effort test. Percent-of-HRmax zones are used here; Karvonen (heart-rate-reserve) zones are only shown once you enter a known resting heart rate.
Method: percentage of estimated HRmax. Formulas: Tanaka et al. 2001 (men), Gulati et al. 2010 (women). Last reviewed . Educational information only — not medical advice.
Zone 4 sits around your lactate threshold — the intensity above which blood lactate accumulates faster than your body can clear it. Sustained work in this zone teaches the muscles and cardiovascular system to buffer and clear lactate more efficiently, raising the pace or power you can hold "at threshold" without a runaway acidosis response.
Prescription: intervals of 5–15 min at Zone 4 with 2–4 min easy recovery, total work 20–40 min, once or twice per week.
Zone 5 targets your maximal oxygen uptake (VO₂max) — the highest rate at which your body can consume and use oxygen. Work in Zone 5 stresses the entire oxygen delivery cascade: stroke volume, cardiac output, capillary density, and mitochondrial oxygen extraction.
Prescription: the classic 4 × 4 min protocol (4 min at 90–95% HRmax, 3 min easy jog, repeat 4 times) is one of the most-studied and most-effective VO₂max sessions, popularised by the Norwegian University of Science and Technology's cardiac rehabilitation research.
Reference: Helgerud J, et al. Aerobic high-intensity intervals improve VO₂max more than moderate training. Medicine & Science in Sports & Exercise. 2007;39(4):665–71.
Both zones are neuromuscular-taxing. A hard Zone 5 session requires 48–72 hours before another high-intensity effort; a threshold session, 24–48 hours. Sandwich them between easy Zone 1–2 days, and never stack them back-to-back if you value long-term progression over short-term feels.
| Zone | Name | % HRmax | BPM (age 30) | Primary use |
|---|---|---|---|---|
| 1 | Recovery | 50–60% | 94–112 | Warm-up, recovery, active rest |
| 2 | Endurance | 60–70% | 112–131 | Aerobic base, fat oxidation |
| 3 | Aerobic | 70–80% | 131–150 | Tempo, aerobic capacity |
| 4 | Threshold | 80–90% | 150–168 | Lactate threshold intervals |
| 5 | Maximum | 90–100% | 168–187 | VO₂ max, neuromuscular power |
Formula-based calculators typically estimate HRmax within ±10–15 bpm. They are accurate enough to structure training for recreational athletes but not a substitute for a supervised max test.
Karvonen uses heart rate reserve (HRR = HRmax − HRrest). Target HR = HRrest + (Intensity% × HRR). It personalises zones by accounting for resting heart rate.
Your bpm targets stay the same, but heart rate response differs by sport. Cycling HR is typically 5–10 bpm lower than running at equivalent perceived effort due to the seated position.
Zone 2 maximises the percentage of calories from fat, but higher intensities burn more total calories per minute. Long-term fat loss is driven by total weekly energy balance.
Disclaimer: This calculator is for informational purposes only and does not provide medical advice. Always consult with a healthcare professional before starting any new exercise program.
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