Warm-up / Recovery 50%–60%
Very easy, full conversation possible
Good for warm-ups, cool-downs and active recovery. Fat contributes a fair share, but total calories burned are low.
Fat Burning Heart Rate
Find your
optimal fat-burning zone
The same age with a different resting heart rate gives you a different fat-burning zone. This tool calculates your range with both the Karvonen formula (resting heart rate included) and the traditional formula (220 − age), so the difference is clear at a glance.
2
formulas compared
5
training zones
0
sign-up, always free
Enter your details
Heart Rate Zones
What do the five zones mean?
The percentages below are training intensity: the Karvonen formula uses your heart-rate reserve (HRR) as its basis and the traditional formula uses your maximum heart rate (HRmax), so the same intensity produces different bpm values.
Fat-burning zone 60%–70% Best for fat burning
Breathing faster, still able to talk
The highest proportion of energy from fat. Aim for a steady pace lasting 30 minutes or more.
Aerobic endurance 70%–80%
Talking takes real effort
The strongest gains in heart and muscle endurance, and the highest total calorie burn.
Anaerobic / Hard 80%–90%
Only short sentences
Lactate builds up quickly. Great for intervals, not meant to be held for long.
Maximum effort 90%–100%
Barely able to speak
For short sprints or advanced training only — always listen to your body.
Recent calculations
The Formulas
How do the two formulas differ?
Both start from your maximum heart rate (HRmax = 220 − age). The difference is whether your resting heart rate is taken into account. A lower resting heart rate usually means better fitness, and the Karvonen formula then gives a range closer to your own capability.
Karvonen formulaResting HR included
Target HR = ((HRmax − HRrest) × intensity%) + HRrest
HRmax = 220 − age; HRrest = resting heart rate; (HRmax − HRrest) is your heart-rate reserve (HRR)
- Best if you already exercise and want your own numbers rather than an age-group average.
- The lower your resting heart rate, the lower the target bpm at the same intensity.
- You need an accurate resting heart rate — measure it in the morning before getting up.
Traditional formulaNo resting HR
Target HR = HRmax × intensity% = (220 − age) × intensity%
Age is the only variable
- The quickest and easiest to remember — the default on most treadmills and watches.
- For people with a low resting heart rate (good fitness) the result tends to be too high.
- For people with a high resting heart rate it may underestimate the intensity they can handle.
FAQ
Frequently asked questions
The questions we are asked most often about fat-burning heart rate, resting heart rate and choosing a formula.
Why do the two formulas give different numbers, and which one should I use?
The traditional formula uses age only, so it represents the average of your age group. The Karvonen formula also includes your resting heart rate, so it reflects your current fitness. If you have a reliable resting heart rate, use the Karvonen formula as your main guide and the traditional formula as a reference.
How long should I stay in the fat-burning zone?
A common guideline is at least 150 minutes of moderate cardio per week — for example 30–45 minutes, 3–5 times a week. A pace you can maintain consistently matters more than short bursts of maximum effort.
How do I know I am in the zone without a heart-rate monitor?
Use the talk test: in the fat-burning zone your breathing is faster and you sweat lightly, but you can still speak a full sentence. Once you can only manage short phrases, you are usually in the aerobic zone or higher. You can also check your pulse manually for 15 seconds and multiply by four.
How do I measure my resting heart rate accurately?
The most accurate way is right after waking up, before getting out of bed: count your pulse at the wrist or neck for 60 seconds. Averaging three consecutive days is even better. If you measure later in the day, sit quietly for five minutes first. Caffeine, poor sleep, illness and stress all push the number up.
Is “220 − age” accurate?
It is a convenient rule of thumb; individual error can reach 10–15 beats per minute. If your watch has measured your maximum heart rate, or you have had an exercise test, use that real value instead of 220 − age.
Do I have to stay in the fat-burning zone to make progress?
No. The fat-burning zone burns the highest proportion of fat, but higher intensities burn more total calories. Combining both — for example two longer fat-burning sessions plus one or two interval sessions a week — usually works best for body composition and fitness.
Health note: This tool estimates your maximum heart rate as 220 − age, which is a population average. Your real maximum heart rate varies with genetics, training status and age, so treat these numbers as a general reference for healthy adults.
If you take medication that affects heart rate (such as beta blockers), have a cardiovascular condition, are pregnant, or experience chest tightness, dizziness or unusual breathlessness during exercise, please consult a doctor or qualified coach first — do not set your training intensity from this page alone.