Target Heart Rate Calculator

About the Target Heart Rate Calculator

A target heart rate calculator determines the optimal heart rate zones for different types of cardiovascular exercise — from fat-burning easy aerobic work to high-intensity interval training — based on your age and resting heart rate. Training at the right heart rate intensity produces specific physiological adaptations: easy aerobic work builds cardiovascular base and burns fat; threshold training improves lactate clearance and race pace; VO2 max training maximises aerobic power. Without heart rate guidance, most people train in a poorly defined "moderate" zone that is too hard for easy days (accumulating unnecessary fatigue) and not hard enough for hard days (failing to produce sufficient training stimulus). Our free target heart rate calculator uses both the simple age-based formula (220 minus age) and the more accurate Karvonen formula (which accounts for your individual resting heart rate) to give you personalised training zones. Results are displayed as both beats per minute (BPM) and percentage of maximum heart rate for each of the five standard training zones used in endurance sports.

How It Works

Step 1 — Maximum Heart Rate (MHR): Age-based formula: MHR = 220 - age. More accurate formula by Tanaka: MHR = 208 - (0.7 x age). Example: 35-year-old. MHR (simple) = 220 - 35 = 185 bpm. MHR (Tanaka) = 208 - 24.5 = 183.5 bpm. Step 2 — Karvonen formula for heart rate reserve (HRR): Heart Rate Reserve = MHR - Resting Heart Rate. Target HR for intensity% = ((MHR - RHR) x intensity%) + RHR. Example: 35-year-old, resting HR 60 bpm. HRR = 185 - 60 = 125. Zone 2 (60-70% HRR) = (125 x 0.60 + 60) to (125 x 0.70 + 60) = 135-148 bpm. Five standard zones: Zone 1 (50-60%) = active recovery. Zone 2 (60-70%) = aerobic base, fat burning. Zone 3 (70-80%) = tempo/aerobic threshold. Zone 4 (80-90%) = lactate threshold, race pace. Zone 5 (90-100%) = VO2 max, maximum effort.

Tips & Best Practices

• ✓The "fat burning zone" (Zone 2, 60-70% MHR) burns the highest percentage of fat as fuel, but higher intensity zones burn more total calories per minute — both have a role in a comprehensive training programme.
• ✓Zone 2 training is the cornerstone of endurance performance: elite marathon runners and cyclists spend 75-80% of their training volume in Zone 2, building the aerobic engine that supports all higher-intensity work.
• ✓Heart rate drift: during long Zone 2 efforts in heat or at altitude, heart rate will gradually rise (cardiac drift) even at constant effort. Reduce pace to maintain the target zone rather than increasing to "keep up" with the drifting heart rate.
• ✓The 220-age formula has high individual variability: standard deviation is approximately 10-12 bpm. A 40-year-old might have a true max heart rate anywhere from 158 to 198 bpm using this formula. Karvonen formula using measured (not estimated) max HR is significantly more accurate.
• ✓Measuring your true maximum heart rate: perform a 20-minute aerobic warm-up, then run as hard as possible uphill for 2-3 minutes, noting the highest HR recorded. This is more accurate than any formula.
• ✓Overtraining warning sign: if your resting heart rate is consistently 5-10 bpm above normal for several consecutive days, this may indicate inadequate recovery — reduce intensity and volume until it normalises.
• ✓Heart rate variability (HRV): a higher HRV (more variation between heartbeats) indicates better autonomic nervous system recovery. Many athletes use HRV apps to guide daily training intensity decisions.
• ✓Medications affecting heart rate: beta-blockers significantly lower maximum and resting heart rate, making all standard heart rate formulas and zones inaccurate. Athletes on beta-blockers should use perceived exertion (RPE) rather than heart rate for training guidance.

Who Uses This Calculator

Beginner runners and cyclists use the target heart rate calculator to avoid the common mistake of training too hard on easy days — discovering that their comfortable-feeling training pace often exceeds Zone 2, explaining why they feel chronically fatigued. Endurance athletes preparing for marathons, triathlons, and cycling events use it to structure polarised training with clear zone demarcation between easy aerobic work and hard threshold sessions. Personal trainers prescribe specific heart rate zones to clients for cardio sessions, replacing vague instructions like "moderate intensity" with quantitative, monitored targets. Cardiac rehabilitation patients use target heart rate guidance from their cardiologist — often prescribed as a maximum heart rate limit — to ensure safe exercise intensity during recovery from cardiac events. Sports science students use the Karvonen formula as a foundational exercise physiology calculation. Fitness app developers incorporate heart rate zone calculations into their training programmes and workout recommendations.