Target Heart Rate Calculator — Free Online Training Zone Tool

How to Use the Target Heart Rate Calculator

1. Enter your age: Type your current age in years. The calculator uses the standard formula of 220 minus your age to estimate your maximum heart rate. This is a population-level estimate — your actual maximum heart rate may differ by up to 10-12 bpm. If you know your actual max heart rate from testing, note that this calculator uses the estimated value.
2. Enter your resting heart rate: Type your resting heart rate in beats per minute (bpm). For the most accurate result, measure your pulse first thing in the morning before getting out of bed. Place two fingers on your wrist or neck and count beats for 60 seconds. The default value of 65 bpm represents a typical resting rate for a moderately active adult.
3. Review your training zones: The results panel displays your estimated maximum heart rate, your heart rate reserve (max HR minus resting HR), and five training zones. Each zone shows a specific BPM range and a description of the training benefit. The color coding helps you quickly identify zones during workouts — from blue (warm-up) through green and yellow (aerobic) to orange and red (anaerobic and max effort).

Use these zones with a heart rate monitor during exercise to ensure you are training at the right intensity for your goals. Most of your training time (about 80%) should be spent in Zones 1 and 2, with the remaining 20% in Zones 3 through 5.

Target Heart Rate Formula (Karvonen Method)

Variables Explained

• Maximum Heart Rate (Max HR): The highest heart rate your body can achieve during all-out effort. Estimated as 220 minus your age. For a 30-year-old, Max HR = 220 - 30 = 190 bpm.
• Resting Heart Rate (Resting HR): Your heart rate at complete rest, measured in beats per minute. This reflects your baseline cardiovascular fitness — lower resting rates generally indicate better fitness. Normal range for adults: 60-100 bpm.
• Heart Rate Reserve (HRR): The difference between your max HR and resting HR. This represents the working range of your heart. A person with Max HR 190 and Resting HR 65 has an HRR of 125 bpm.
• Intensity Percentage: The fraction of HRR at which you want to train. Zone boundaries are 50/60%, 60/70%, 70/80%, 80/90%, and 90/100% of HRR.

Step-by-Step Calculation Example

Suppose you are 35 years old with a resting heart rate of 60 bpm:

1. Max HR: 220 - 35 = 185 bpm
2. Heart Rate Reserve: 185 - 60 = 125 bpm
3. Zone 2 lower bound (60%): 60 + (125 x 0.60) = 60 + 75 = 135 bpm
4. Zone 2 upper bound (70%): 60 + (125 x 0.70) = 60 + 87.5 = 148 bpm
5. Zone 4 lower bound (80%): 60 + (125 x 0.80) = 60 + 100 = 160 bpm
6. Zone 4 upper bound (90%): 60 + (125 x 0.90) = 60 + 112.5 = 173 bpm

For this person, easy aerobic training would be in Zone 2 at 135-148 bpm, while hard interval work would be in Zone 4 at 160-173 bpm. The Karvonen method provides more personalized zones than simply using a percentage of max HR because it accounts for fitness level through the resting heart rate.

Practical Examples

Example 1: Emma Starting a Cardio Program

Emma is a 42-year-old who has been sedentary and wants to start a walking and jogging program. Her resting heart rate is 78 bpm:

• Max HR: 220 - 42 = 178 bpm
• Heart Rate Reserve: 178 - 78 = 100 bpm
• Zone 1 (warm-up): 78 + (100 x 0.50) to 78 + (100 x 0.60) = 128-138 bpm
• Zone 2 (fat burn): 78 + (100 x 0.60) to 78 + (100 x 0.70) = 138-148 bpm

Emma's coach recommends spending the first 4 weeks training exclusively in Zones 1-2, keeping her heart rate between 128 and 148 bpm. This builds aerobic fitness safely without overexertion. She uses a wrist-based heart rate monitor during walks to stay within range.

Example 2: Kevin Optimizing Marathon Training

Kevin is a 29-year-old experienced runner training for a marathon. His resting heart rate is 52 bpm, reflecting his training history:

• Max HR: 220 - 29 = 191 bpm
• Heart Rate Reserve: 191 - 52 = 139 bpm
• Zone 2 (easy runs): 52 + (139 x 0.60) to 52 + (139 x 0.70) = 135-149 bpm
• Zone 3 (tempo): 52 + (139 x 0.70) to 52 + (139 x 0.80) = 149-163 bpm
• Zone 4 (intervals): 52 + (139 x 0.80) to 52 + (139 x 0.90) = 163-177 bpm

Kevin structures his week with 4 easy runs in Zone 2 (135-149 bpm), 1 tempo run in Zone 3 (149-163 bpm), and 1 interval session reaching Zone 4 (163-177 bpm). He uses the pace calculator alongside heart rate to correlate his pace with zone data.

Example 3: Patricia Monitoring Recovery After Illness

Patricia is a 55-year-old returning to exercise after recovering from a respiratory illness. Her resting heart rate, which was 68 bpm before illness, is now 82 bpm:

• Max HR: 220 - 55 = 165 bpm
• Heart Rate Reserve: 165 - 82 = 83 bpm
• Zone 1 (recovery): 82 + (83 x 0.50) to 82 + (83 x 0.60) = 124-132 bpm
• Zone 2 (light): 82 + (83 x 0.60) to 82 + (83 x 0.70) = 132-140 bpm

Patricia's doctor recommends staying in Zone 1 for the first two weeks and monitoring how she feels. Her elevated resting heart rate means her zones are compressed (smaller range), which is normal during recovery. As her resting heart rate drops back toward 68, she can recalculate and gradually increase intensity.

Heart Rate Training Zone Reference Table

Tips and Complete Guide to Heart Rate Training

Why Heart Rate Training Works

Heart rate-based training provides an objective measure of exercise intensity that accounts for day-to-day variations in fitness, fatigue, stress, and environmental conditions. Unlike pace, which stays the same regardless of how your body feels, heart rate reflects actual physiological stress. On a hot day or after poor sleep, your heart rate at a given pace will be higher than usual — this tells you to ease up. Conversely, as fitness improves, the same heart rate sustains a faster pace, providing clear evidence of progress.

The 80/20 Training Principle

Research consistently shows that the most effective endurance training follows an 80/20 intensity distribution: roughly 80% of training volume at low intensity (Zones 1-2) and 20% at moderate-to-high intensity (Zones 3-5). This applies across all levels from recreational joggers to Olympic athletes. The common mistake of training too hard on easy days and too easy on hard days (the "moderate intensity rut") leads to slower improvement and higher injury rates. Heart rate monitoring enforces this distribution by giving you an objective boundary between easy and hard efforts.

Factors That Elevate Resting Heart Rate

Your resting heart rate is not a fixed number — it varies day to day based on several factors. Elevated resting heart rate can indicate overtraining, illness, dehydration, stress, poor sleep, or high caffeine intake. If your resting heart rate is 5 to 10 bpm higher than normal for several consecutive days, this is often a sign that your body needs more recovery. Many athletes track morning resting heart rate as an early warning system for overtraining and illness. A consistently decreasing resting heart rate over weeks and months is a reliable indicator of improving cardiovascular fitness.

Common Mistakes to Avoid

• Ignoring your resting heart rate when calculating zones: Using simple percentage of max HR (e.g., 70% of 190 = 133 bpm) gives less personalized zones than the Karvonen method. Two people with the same max HR but different resting rates should train at different intensities.
• Relying solely on the 220 minus age formula: This formula has a large margin of error. If your calculated zones feel obviously wrong (too easy or impossibly hard), consider getting a graded exercise test to determine your actual max heart rate.
• Training in Zone 3 too often: Zone 3 (moderate effort) is sometimes called the "gray zone" because it is too hard to be easy recovery training but not hard enough to produce the adaptations of high-intensity work. Most training time should be in Zone 2 (easy) or Zone 4-5 (hard).
• Not recalculating zones as fitness improves: As your resting heart rate decreases with improved fitness, your training zones shift. Recalculate zones every 2 to 3 months or whenever your resting heart rate changes significantly.
• Comparing heart rate zones with others: Heart rate zones are highly individual. A heart rate of 150 bpm might be Zone 2 for one person and Zone 4 for another. Train based on your own zones, not someone else's numbers.

Frequently Asked Questions