Karvonen Formula Calculator

Karvonen Formula Calculator. Enter your age, resting heart rate, and choose your intensity level to calculate your target heart rate using the Karvonen Formula. You'll get your personalized target heart rate range across five training zones — from light recovery to maximum effort — based on your individual heart rate reserve. Also try the VO2 Max Calculator (General).

Results

Target Heart Rate Range

Maximum Heart Rate

Heart Rate Reserve

Target HR (Lower Bound)

Target HR (Upper Bound)

Results Table

What is the Karvonen Formula?

The Karvonen Formula is a method for calculating target heart rate that accounts for your individual fitness level by using your heart rate reserve (HRR) — the difference between your maximum and resting heart rate. The formula is: THR = ((MHR − RHR) × Intensity) + RHR. This makes it more personalized than simple percentage-of-max-heart-rate methods. See also our calculate Anaerobic Zone (Lower Bound), Maximum Heart Rate (BPMmax) & Anaerobic Zone (Upper Bound) — Anaerobic Threshold.

How do I calculate heart rate reserve?

Heart rate reserve (HRR) is simply your maximum heart rate minus your resting heart rate. For example, if your max HR is 190 bpm and your resting HR is 65 bpm, your HRR is 125 bpm. The Karvonen Formula uses this reserve to scale your target heart rate based on effort intensity.

Is the 220 minus age formula accurate for maximum heart rate?

The 220 − Age formula is a common estimate but can vary by ±10–20 bpm for individuals. It's a convenient starting point, especially if you haven't done a max effort test. For greater accuracy — particularly for serious athletes — a supervised maximum exercise test or a 3-minute all-out field test is recommended.

How do I accurately measure my resting heart rate?

Measure your resting heart rate first thing in the morning before getting out of bed. Count your pulse for 60 seconds (or 30 seconds and double it). For best accuracy, take readings on 3–5 consecutive mornings and use the average, as stress, training load, and sleep can cause day-to-day variation of 5–10 bpm.

Which training zone should I spend the most time in?

For general health and aerobic fitness, most experts recommend spending the majority of your training time in Zone 2 (moderate intensity, 40–59% HRR). This builds aerobic base, improves fat metabolism, and aids recovery. Higher zones (4–5) are reserved for interval training and should make up a smaller portion of weekly volume.

What is the target heart rate for the fat-burning zone?

The fat-burning zone is generally considered to be around 50–70% of your heart rate reserve using the Karvonen Formula. At this intensity, your body relies more heavily on fat as a fuel source. However, total calorie burn and training consistency matter more for fat loss than staying exclusively in this zone.

Why does the Karvonen Formula give different results than basic heart rate percentage methods?

Basic methods calculate target HR as a percentage of maximum heart rate only (THR = MHR × Intensity%). The Karvonen Formula applies the intensity percentage to your heart rate reserve and then adds back the resting heart rate. This means two people with the same max HR but different resting heart rates will get different training zones, making the Karvonen approach more individualized.

Should I adjust my training zones for environmental factors like heat or altitude?

Yes. Heat and humidity increase cardiovascular strain, causing your heart rate to rise at any given effort level. At altitude, reduced oxygen availability also elevates heart rate. In these conditions, consider working at the lower end of your target zone or using perceived exertion alongside heart rate to avoid overtraining. You might also find our calculate Training Load (TRIMP) TRIMP Score useful.