A target heart rate calculator estimates your maximum heart rate from age and breaks down two common training zones: the fat-burn zone (50-70% of max) and the cardio zone (70-85% of max). Enter your age, the calculator returns the bpm range for each zone using the Tanaka formula, which is more accurate for older adults than the older "220 minus age" rule.
Useful for setting effort targets on a treadmill, exercise bike, rower, or outdoor run. Most modern fitness watches let you set custom zones, these numbers are a sensible starting point if you don't have a chest strap or recent stress test.
Key takeaway
The "fat-burn zone" name is a marketing artifact, not a metabolic truth. Higher-intensity cardio burns more total fat per minute, just at a lower percentage of total calories. The fat-burn zone is just easier to sustain for longer durations. For weight management, total calorie burn matters more than the zone you're in, but the cardio zone is where cardiovascular fitness gains happen fastest.
How it's calculated
Maximum heart rate is the highest beats-per-minute your heart can achieve at maximum effort. Two common formulas:
- 220 − age (Fox formula, 1971): the textbook standard, but consistently overestimates max HR for older adults and underestimates for some younger ones.
- 208 − 0.7 × age (Tanaka formula, 2001): based on a meta-analysis of 351 studies; significantly more accurate than 220 − age. This calculator uses the Tanaka formula.
Training zones as percentages of max HR:
- 50-60%: Warm-up / very light. Recovery rides, gentle walking.
- 60-70%: Fat-burn / "easy" zone. Sustainable for long durations; good for endurance base-building.
- 70-80%: Aerobic / cardio zone. Improves cardiovascular fitness; typical "moderate" workout intensity.
- 80-90%: Threshold / lactate threshold. Pushes endurance ceiling; typical for tempo runs and race-pace efforts.
- 90-100%: Max effort / VO2 max. Sprint intervals; can only be held for short bursts.
For best accuracy, replace the formula estimate with your actual measured max HR from a graded exercise test or a recent all-out 5K finish-line reading on a chest strap.
Source: Max HR via Tanaka (208 − 0.7 × age), more accurate than the older 220 − age formula
Examples
35-year-old training for general fitness
- Age 35 yr
At age 35, estimated max HR is 184 bpm. Fat-burn zone runs 92-129 bpm; cardio zone runs 129-156 bpm. For a typical cardio session, aim for the 130-150 bpm range, sustainable for 30-45 min and trains aerobic capacity. The older 220 − age formula would give a max of 185, close in this case, but the gap widens with age.
55-year-old beginning cardio program
- Age 55 yr
At age 55, max HR estimates to 170 bpm (Tanaka) versus 165 from the older 220 − age formula, a 5 bpm gap that meaningfully shifts the zones. Cardio zone is roughly 119-144 bpm. For a beginning program, the lower end of fat-burn (85-100 bpm) is a safer starting point that builds aerobic capacity without overreaching.
Frequently asked questions
How do I calculate my max heart rate?
Use the Tanaka formula: Max HR = 208 − 0.7 × age. So at age 40, that's 208 − 28 = 180 bpm. Tanaka is significantly more accurate than the older "220 − age" rule, especially over age 40. The formula is a population average; your individual max can be ±10-15 bpm from the predicted value. For precise targets, a graded exercise test or all-out treadmill protocol gives a real measured number.
What's the difference between fat-burn zone and cardio zone?
Fat-burn zone (50-70% of max HR) burns a higher percentage of calories from fat, but fewer total calories per minute, because the effort level is lower. Cardio zone (70-85%) burns a lower percentage from fat but more total calories overall, and it's where most cardiovascular fitness gains happen. For weight management, total calories matters more than zone. For fitness improvements, spend most of your time in the cardio zone with occasional fat-burn / easy days for recovery.
Should I worry if I exceed my predicted max HR?
Not necessarily, the formula is just a population average, and individuals genuinely vary by ±10-15 bpm from the prediction. Briefly hitting 5-10 bpm above predicted max during a hard workout is normal and not dangerous for healthy adults. However: any unexplained chest pain, dizziness, or sudden inability to continue is a stop-and-call-a-doctor signal regardless of the heart rate number. Don't push toward maximum if you have known heart conditions or are on rate-limiting medications.
Do beta blockers affect heart rate calculations?
Yes. Beta blockers lower both resting and exercising heart rate, often by 20-30 bpm. The formula-based max HR will overshoot for someone on a beta blocker, using the formula's targets could push you to dangerously high effort to "hit" zones the medication is preventing you from reaching. People on rate-limiting medications should ignore HR-based targets and use perceived exertion (Borg scale) or talk-test cues instead, ideally guided by a clinical exercise physiologist.