Anaerobic Threshold Calculator

Created by Piotr Wawrzyńczyk
Reviewed by Hanna Pamuła, PhD and Steven Wooding
Based on research by
Fox SM 3rd, Naughton JP, Haskell WL Physical activity and the prevention of coronary heart disease Annals of Clinical Research (1971)See 2 more sources
Nes BM, Janszky I, Wisløff U, et al. Age-predicted maximal heart rate in healthy subjects: the HUNT fitness study The Scandinavian Journal of Medicine & Science in Sports (2013)Tanaka H, Monahan K, Seals D. Age-predicted maximal heart rate revisited Journal of the American College of Cardiology (2001)
Last updated: Jan 17, 2023

The anaerobic threshold calculator allows you to quickly determine your ideal average anaerobic heart rate, as well as your anaerobic heart rate zone. You may also use it in reverse by providing an anaerobic threshold to compute the expected age.

Are you interested in what anaerobic means or what is an anaerobic threshold? Then read on!

What heart rate is anaerobic?

Let's start by explaining what an anaerobic threshold is. During an exercise, our heart quickens up its pace – this happens to adjust the intensity of blood flow, which keeps our muscles active. As it turns out, the increase in our pulse is not arbitrary – we can define different heart rate zones depending on a percentage of one's maximal heart rate:

  • Recovery zone: from 50% to 60%.
  • Endurance zone: from 60% to 70%.
  • Aerobic zone: from 70% to 80%.
  • Anaerobic zone: from 80% to 90%.
  • VO2 max zone: up to 100%.

Here we focus on the fourth zone. What does anaerobic mean? In contrast to the aerobic zone, where oxygen is the main energy source for our body, in the anaerobic zone, oxygen is insufficient. Our bodies switch to burning the glucose, which produces lactic acid – the famous culprit of after-exercise muscle aches. Training in an anaerobic zone allows us to lose more weight, build muscles and improve bone density and strength. However, you must remember to take care of proper recovery after training – check it out with our heart rate recovery calculator!

According to the anaerobic threshold formula used in the anaerobic threshold calculator, your heart rate should lay around 85% of your maximal heart rate:

anaerobic heart rate = maximal heart rate × 0.85

You can check out the advanced form of the calculator, where a range of anaerobic threshold zone is additionally displayed.

Formula behind the anaerobic threshold calculator

The formula for anaerobic threshold is pretty simple (as simple as calculating your heart rate with heart rate calculator), but where do the numbers come from?

First, let's deal with the calculation of maximal heart rate (BPMmax\small\rm BPM_{max}), measured in beats per minute. There are many formulas; some of the most popular are Fox & Haskell formula, Nes formula, and Tanaka, Monahan & Seals formula – you can check out other formulas in our max heart rate calculator.

The Fox & Haskell formula:

BPMmax=220age\small \rm BPM_{max} = 220 - age

The Nes formula:

BPMmax=2110.64×age\small\rm BPM_{max} = 211 - 0.64 \times age

And finally, the Tanaka, Monahan, & Seals formula:

BPMmax=2080.7×age\small\rm BPM_{max} = 208 - 0.7 \times age

As you can see above, each of those formulas may return slightly different results, even for the same age – but fear not, this is only a reasonably accurate estimate. Besides age, your heart rate depends on your physical condition, stress, and other factors.

Now we can talk about the second mysterious constant from the equation – the 0.85 multiplier. As mentioned before, the anaerobic heart rate zone should lay between 80% and 90% of a maximum heart rate – and we want to find an average of those, which would be exactly 85% (or 0.85, as a decimal). If you have doubts about this, make sure to consult our average calculator.

As in the case of calculating maximum heart rate, this is only an estimation – some experts propose that the anaerobic threshold should lay from 80% up to 95% of a maximum heart rate.


What affects anaerobic threshold?

As we can see from the formula used in the anaerobic threshold calculator, the main factor influencing the anaerobic heart rate is one's age – the rate decreases as we get older. The other factors are genetics or general conditioning, like energy levels or even altitude – the higher we get, the less oxygen reaches our muscles, changing our heart rate zones.

How long can you sustain anaerobic heart rate?

As it turns out, not for long – one should be able to keep their heart in an anaerobic heart rate zone for from thirty to sixty seconds. Professional athletes are able to lengthen this period to about two minutes. In contrast, you can stay in the aerobic heart rate zone for over forty minutes!

What is a heart rate?

Heart rate is the number of heartbeats a heart performs per minute. It varies with age – a resting heart rate for a typical adult lies between 60 and 100 BPM (beats per minute).

How to measure the heart rate?

First, you need to find your pulse – either on the thumb side of your wrist (radial artery) or on your neck, on either side of the windpipe (carotid artery). After feeling the pulse, set up a timer for 15 seconds and count the beats during the countdown. The number you receive is your heart rate per quarter of a minute – to find out the BPM (beats per minute), just multiply it by 4. That's it!

Piotr Wawrzyńczyk
Formula type
Haskell & Fox formula
Anaerobic threshold
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