Karvonen builds the zone off your reserve, not raw max
The gap between your maximum and resting pulse is your heart rate reserve. Take a slice of it for the intensity you want, then add your resting rate back on. Because it starts from your own resting pulse, two people the same age get different target rates, which a plain "% of max" never captures.
Target heart rate by intensity
Worked for a 30-year-old (max 190) with a resting pulse of 70, so a reserve of 120 beats.
| Intensity | Zone | Target (this example) | Feels like |
|---|---|---|---|
| 50% | Warm-up | 130 bpm | Very easy, can chat freely |
| 60% | Fat burn / base | 142 bpm | Easy, full sentences |
| 70% | Aerobic | 154 bpm | Working, short sentences only |
| 80% | Anaerobic | 166 bpm | Hard, cannot hold a conversation |
| 90% | VO2 max | 178 bpm | All-out, short intervals only |
Most steady cardio lives in the 50–70% band; 70–85% is threshold work. Above 90% is for brief intervals, not daily training.
Getting the inputs right
- Resting rate, measured properly. Morning, in bed, before moving. A chest-strap monitor reads more accurately than a wrist sensor during fast movement.
- Max is an estimate. 220 minus age is a starting point with real spread. A stress test gives your true ceiling.
- Vary the zone. Training in one band every day stalls progress and risks overtraining. Mix easy, moderate, and hard days.
- Illness moves the baseline. Fever, dehydration, or stress raise your resting pulse, which skews every target. Wait until you have recovered.
Common questions
Why is the Karvonen formula better than a plain percentage of max heart rate?
It uses your heart rate reserve, the gap between your maximum and resting rate, so it factors in your fitness. A trained person with a low resting pulse gets a personalized zone, while a flat percentage of max heart rate ignores that entirely.
What resting heart rate should I use?
Measure it first thing in the morning, before you get out of bed. A normal adult range is 60 to 100 beats per minute; trained endurance athletes often sit at 40 to 60. Take it on several mornings and use the average.
How accurate is 220 minus age for maximum heart rate?
It is only an estimate and can be off by 10 to 20 beats per minute in either direction. If you want a real number, a supervised graded exercise test on a treadmill or bike is far more reliable.
