Fitness
Target Heart Rate Calculator
Get your training heart rate zones from your age, refined with the Karvonen method when you add a resting heart rate.
Calculation inputs
Leave resting heart rate blank to use the simpler age-based calculation.
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Estimates only, for general information. Not medical advice — check with a doctor before starting hard training.
About this calculator
A target heart rate calculator estimates the heart rate ranges commonly associated with different training intensities, based on age and, optionally, resting heart rate. It's used as a general reference point during exercise, not as medical guidance.
How the calculation works
- Maximum heart rate = 220 − age
- Without a resting heart rate: zone = maximum heart rate × zone percentage
- Karvonen: zone = ((maximum − resting) × zone percentage) + resting
Notes and assumptions
The 220 − age rule is a population average and can be off by 10-12 beats for any individual.
Measure resting heart rate first thing in the morning, before getting out of bed, for the most useful number.
How it works in plain English
The simplest approach starts with an estimated maximum heart rate, commonly calculated as 220 minus your age. From that maximum, percentage ranges are used to describe general intensity zones, such as a lower range often associated with easier, sustained effort and a higher range associated with more vigorous effort.
A more refined method, the Karvonen formula, also factors in resting heart rate, which is your heart rate at complete rest, typically measured first thing in the morning. This method calculates a heart rate reserve, the gap between resting and maximum heart rate, and applies the target percentage to that reserve before adding resting heart rate back in. This tends to produce more personalized ranges than the age-only method.
Both approaches are estimates built from population averages, not measurements of your individual cardiovascular system, so actual maximum heart rate can vary meaningfully from person to person even at the same age.
The formula
- Estimated max heart rate = 220 - age
- Karvonen: target HR = ((max HR - resting HR) x intensity%) + resting HR
Worked example
For a 35-year-old, estimated maximum heart rate is 220 - 35 = 185 beats per minute. A commonly referenced moderate-intensity range of 50-70% of that maximum works out to roughly 93 to 130 beats per minute.
Adding a resting heart rate of 65 bpm and using the Karvonen method for the same 50-70% range: heart rate reserve is 185 - 65 = 120. At 50%, target is (120 x 0.5) + 65 = 125 bpm; at 70%, target is (120 x 0.7) + 65 = 149 bpm, a noticeably different range from the age-only estimate.
Commonly referenced heart rate training zones
| Zone | % of max heart rate | Common description |
|---|---|---|
| Very light | 50-60% | Easy, warm-up effort |
| Light | 60-70% | Fat-burning, conversational pace |
| Moderate | 70-80% | Aerobic, cardio training |
| Hard | 80-90% | Anaerobic threshold |
| Maximum | 90-100% | Peak, short-duration effort |
Zones reflect widely cited percentage-of-maximum guidelines and are general reference points, not individualized prescriptions.
Frequently asked questions
How accurate is the 220 minus age formula?
It's a widely used population average, but individual maximum heart rate can vary by 10 to 15 beats per minute or more from the estimate, even among people of the same age and fitness level, so treat it as a rough guide.
What is the Karvonen method and why use it?
It factors in resting heart rate along with age, producing a target range scaled to your own heart rate reserve rather than a flat percentage of an estimated maximum. Many find it a more personalized starting point, especially for people with a notably low or high resting rate.
How do I find my resting heart rate?
It's typically measured by checking your pulse for a full minute right after waking up, before getting out of bed or having caffeine, on a few different mornings and averaging the results together. Taking several mornings this way smooths out day-to-day fluctuations caused by sleep quality, stress, or the previous day's activity, giving a steadier baseline number to plug into the Karvonen calculation.
Can heart rate zones be affected by things other than exercise intensity?
Yes. Heat, humidity, hydration, sleep, stress, altitude, and certain medications can all shift heart rate independent of effort level, so the same zone number can feel noticeably different from one day to the next. Because of this, many people treat heart rate zones as a general guide alongside perceived effort rather than a strict, unchanging target to hit every session.
Should I use this calculator instead of talking to a doctor?
No. This tool provides general reference numbers based on standard population formulas rather than a personal cardiovascular assessment. Anyone with heart conditions, a family history of heart disease, or other health concerns should check with a qualified medical professional before using heart rate zones to guide exercise intensity or starting a new exercise program.