Heart Rate Zone Calculator

How Heart Rate Training Zones Work

Training in different heart rate zones produces different physiological adaptations. Zone 2 (60–70% max HR) builds aerobic base and fat oxidation capacity. Zone 4 (80–90%) improves lactate threshold. Zone 5 (90–100%) maximizes VO2 max. Most training programs balance easy aerobic work with targeted high-intensity sessions.

If you provide your resting heart rate, the calculator uses the Karvonen formula, which uses Heart Rate Reserve (max HR − resting HR) for more personalized zones.

Heart Rate Zone Formulas

Estimated Max HR = 220 − Age Simple Zone: Target = Max HR × Zone% Karvonen: Target = Resting HR + (Max HR − Resting HR) × Zone%

Heart Rate Zone Benefits

Zone	Intensity	Primary Benefit	Feel
Zone 1	50–60%	Active recovery	Easy, conversational
Zone 2	60–70%	Fat burning, aerobic base	Comfortable, can talk
Zone 3	70–80%	Aerobic improvement	Moderate effort
Zone 4	80–90%	Lactate threshold	Hard, short sentences
Zone 5	90–100%	VO2 max, speed	Maximum effort, no talking

Frequently Asked Questions

The formula 220 minus age gives a rough estimate. The most accurate method is a field test: after a proper warmup, run or cycle as hard as possible for 2–3 minutes up a steep hill, then check your peak reading. Alternatively, your peak HR during a VO2 max test at a sports science lab is the gold standard.

Zone 2 (60–70% max HR) burns the highest percentage of fat as fuel. However, higher-intensity zones burn more total calories per minute. A mix is optimal: long Zone 2 sessions for aerobic base and fat oxidation efficiency, plus 1–2 high-intensity sessions per week for overall calorie burn and cardiovascular fitness.

The Karvonen formula calculates target heart rate using Heart Rate Reserve (HRR = Max HR − Resting HR). It adjusts for fitness level — fit people with low resting HR get higher absolute targets within each zone. Formula: Target HR = Resting HR + (HRR × Zone%). This is more personalized than simple percentage of max HR.

The 220−age formula has a standard deviation of about 12 bpm, meaning your actual max HR could easily be 10–15 bpm higher or lower. It is a useful starting point but should be validated with actual exercise testing if you are doing precise training. Age-predicted max HR tends to underestimate max HR in very fit older adults.