Health & Medicine · Fitness · Cardio & Endurance
Training Heart Rate Zones Calculator
Calculate your 5 training heart rate zones using the Karvonen formula based on your age, resting heart rate, and desired intensity.
Calculator
Formula
HR_target is the target heart rate at a given intensity. HR_max is the maximum heart rate (220 minus age). HR_rest is resting heart rate measured in BPM. Intensity is the fractional training intensity (e.g. 0.60 for 60%). The term (HR_max - HR_rest) represents the heart rate reserve (HRR).
Source: Karvonen M.J., Kentala E., Mustala O. — 'The effects of training on heart rate', Annales Medicinae Experimentalis et Biologiae Fenniae, 1957.
How it works
The Karvonen formula calculates each zone boundary as a percentage of your Heart Rate Reserve (HRR), which is the difference between your maximum heart rate and your resting heart rate. The target heart rate at any intensity is: HR_target = (HR_max − HR_rest) × intensity + HR_rest. This means two people of the same age but different fitness levels (and therefore different resting heart rates) will have different zone boundaries, making the formula more accurate than age-only methods.
Maximum heart rate is estimated using one of three validated formulas: the classic Standard formula (220 − age), the Tanaka formula (208 − 0.7 × age), which was derived from a meta-analysis of over 350 studies, or the Gelish formula (207 − 0.7 × age). The Tanaka and Gelish formulas tend to be more accurate for older adults, as the standard formula underestimates HRmax in that population.
The five resulting zones correspond to well-established physiological intensities: Zone 1 (50–60% HRR) promotes active recovery and improves fat metabolism; Zone 2 (60–70% HRR) builds the aerobic base; Zone 3 (70–80% HRR) develops aerobic capacity and tempo pace; Zone 4 (80–90% HRR) targets the lactate threshold; and Zone 5 (90–100% HRR) pushes VO2 max and anaerobic capacity.
Worked example
Example: A 35-year-old runner has a resting heart rate of 55 BPM and uses the Tanaka formula.
Step 1 — Estimate Max HR: HR_max = 208 − (0.7 × 35) = 208 − 24.5 = 183.5 ≈ 184 BPM
Step 2 — Calculate HRR: HRR = 184 − 55 = 129 BPM
Step 3 — Zone boundaries:
Zone 1: (129 × 0.50) + 55 = 119 BPM to (129 × 0.60) + 55 = 132 BPM
Zone 2: 132 BPM to (129 × 0.70) + 55 = 145 BPM
Zone 3: 145 BPM to (129 × 0.80) + 55 = 158 BPM
Zone 4: 158 BPM to (129 × 0.90) + 55 = 171 BPM
Zone 5: 171 BPM to 184 BPM
This runner should aim for 119–132 BPM on easy recovery days, and 158–171 BPM on lactate threshold workouts such as tempo runs.
Limitations & notes
All max HR formulas are population-based estimates with significant individual variation — standard deviation is roughly ±10–12 BPM. The only accurate way to determine your true HRmax is through a maximal exercise test conducted under medical supervision. Resting heart rate should be measured upon waking, before getting out of bed, as activity, caffeine, and stress can elevate it considerably. The Karvonen zones assume a linear relationship between heart rate and exercise intensity, which is a reasonable approximation but breaks down at very high intensities or in extreme heat/humidity. Athletes on beta-blockers or other cardiac medications will have artificially suppressed heart rates and should not use age-based formulas without physician guidance. These zones are general guidelines — individualized lactate testing or metabolic testing provides more precise training zones for competitive athletes.
Frequently asked questions
What is the difference between the Karvonen method and simple percentage of max HR?
Simple percentage methods (e.g. 'train at 70% of max HR') ignore your resting heart rate entirely. The Karvonen method uses heart rate reserve — the range from rest to max — so two people with the same max HR but different resting rates (say 45 BPM vs. 80 BPM) get different zone boundaries. This makes the Karvonen approach more individualized and is especially important for highly trained athletes who have low resting heart rates.
How do I measure my resting heart rate accurately?
Measure it first thing in the morning before getting out of bed, ideally after at least 5 minutes of lying still. Use a pulse oximeter, a heart rate monitor, or count your pulse at your wrist or neck for a full 60 seconds. Avoid caffeine, alcohol, or stress before measuring. Take readings on 3–5 consecutive mornings and average them for a reliable baseline. Resting HR typically ranges from 40–60 BPM in trained athletes and 60–100 BPM in sedentary adults.
Which max HR formula should I use?
The Standard formula (220 − age) is the most widely known but tends to overestimate HRmax in younger adults and underestimate it in older adults. The Tanaka formula (208 − 0.7 × age), published in the Journal of the American College of Cardiology in 2001, was validated across a large dataset and is generally more accurate, especially for adults over 40. The Gelish formula (207 − 0.7 × age) from 2007 is very similar to Tanaka. For most general fitness purposes, any of the three will give useful training guidance.
What should each training zone feel like?
Zone 1 feels like a gentle stroll — you can easily hold a full conversation. Zone 2 feels like a brisk walk or easy jog — conversational but mildly breathless. Zone 3 feels comfortably hard — you can speak in short sentences. Zone 4 feels hard — speaking is difficult and sustainable only for 20–60 minutes. Zone 5 feels maximal — you cannot speak and can only sustain it for seconds to a few minutes. These perceived exertion cues are a useful supplement to your heart rate monitor.
How much time should I spend in each zone?
For general aerobic fitness and endurance development, a polarized or pyramidal training distribution is widely recommended: roughly 75–80% of training time in Zones 1–2 (easy aerobic), about 5–10% in Zone 3, and 15–20% in Zones 4–5 (high intensity). Spending too much time in Zone 3 — sometimes called the 'grey zone' — can lead to cumulative fatigue without the full benefits of either easy aerobic work or high-intensity training. Elite endurance athletes typically train with a similar high-volume low-intensity base.
Can I use these zones for cycling, swimming, and rowing, not just running?
Yes, but with caveats. Heart rate responds differently across sports. Maximum cycling HR is typically 5–10 BPM lower than running HR due to less total muscle mass involvement. Swimming HR is often lower still due to the horizontal body position and cool water temperature. For accurate sport-specific zones, ideally perform a maximal test in each sport. As a practical workaround, many athletes subtract approximately 5 BPM from running-derived zones when using them for cycling.
Last updated: 2025-01-30 · Formula verified against primary sources.