How to Calculate Your Heart Rate Zones for Effective Cardio Training

If you are serious about cardio training, knowing your heart rate zones is the difference between spinning your wheels and making real progress. Your heart rate reveals exactly how hard your body is working and which energy system it is using. Training in the right zone for your goals — whether fat burning, endurance, or speed — makes every minute of exercise count.

The Five Heart Rate Zones

Zone	% of Max HR	Intensity	Primary Benefit
Zone 1	50–60%	Very light	Recovery, warm-up
Zone 2	60–70%	Light	Fat burning, aerobic base
Zone 3	70–80%	Moderate	Cardiovascular endurance
Zone 4	80–90%	Hard	Lactate threshold, speed
Zone 5	90–100%	Maximum	Anaerobic power, sprinting

Step 1: Calculate Your Maximum Heart Rate

The simplest formula is the age-predicted method:

Max HR = 220 – your age

For a 35-year-old, this gives 185 bpm. However, this formula has a margin of error of about ±10–15 bpm. A more accurate version is the Tanaka formula: 208 – (0.7 × age). For a more precise calculation, use our heart rate calculator which includes both formulas and lets you input your resting heart rate for a more personalized result.

Step 2: Calculate Your Zone Ranges

Once you know your max heart rate, multiply it by the zone percentages:

Example for a 35-year-old (max HR = 185 bpm):

• Zone 2 (fat burn): 185 × 0.60 = 111 bpm to 185 × 0.70 = 130 bpm
• Zone 4 (threshold): 185 × 0.80 = 148 bpm to 185 × 0.90 = 167 bpm

Step 3: Train in the Right Zone for Your Goal

Goal	Recommended Zone	Time per Session
Fat loss	Zone 2 (60–70%)	45–60 min
General fitness	Zone 2–3 (60–80%)	30–45 min
5K/10K race	Zone 3–4 (70–90%)	20–40 min intervals
Marathon endurance	Zone 2 (60–70%)	60–120 min
Sprint/explosive power	Zone 5 (90–100%)	5–10 min intervals

Using a Heart Rate Monitor

A chest strap heart rate monitor is the most accurate for zone training. Optical wrist sensors (smartwatches) are less accurate during high-intensity intervals. If you do not have a monitor, the “talk test” is a reasonable substitute: Zone 2 = you can hold a conversation; Zone 4 = you can only speak single words.

Calculate your personal heart rate zones instantly with our heart rate zone calculator and take the guesswork out of your next workout.