VO2 Max Training Zones Calculator

Training zones divide exercise intensity into bands, each producing a different physiological adaptation. The catch is that there are two different ways to draw the lines, and they do not land in the same place.

Percent of maximum heart rate, and why it is the weaker method

The familiar zones are percentages of maximum heart rate. They are easy, and they systematically overstate how hard you are working, because your heart is already beating at rest. At 60% of a maximum of 185 you are at 111 bpm, and if your resting rate is 60 then you are only 33% of the way from rest to flat out. That is a warm-up, not an aerobic base session.

Percent of VO2 max, using heart rate reserve

The better method uses heart rate reserve, the span between your resting and maximum pulse:

Target = resting HR + intensity × (max HR − resting HR)

This is the Karvonen formula, and the reason it belongs on a page about VO2 max is that percent of heart rate reserve tracks percent of VO2 max almost one for one. Swain and Leutholtz established that relationship in the 1990s and it has held up. So a zone written as “70% of VO2 max” translates directly into a heart rate you can read off a watch, and it accounts for your own resting pulse instead of assuming an average one.

For a 35-year-old with a resting pulse of 55 and a maximum of 184, the two methods put the bottom of Zone 2 at 110 bpm and 132 bpm respectively. Twenty-two beats apart, on the zone people spend the most hours in.

The 5 zones, by percent of VO2 max

• Zone 1 (50-60%): active recovery. Genuinely easy. Warm-ups, cool-downs, the day after a hard session.
• Zone 2 (60-70%): aerobic base. Conversational, and the foundation of endurance training. This is where mitochondrial density is built, and it takes hours, not minutes.
• Zone 3 (70-80%): tempo. Moderately hard. The most common training error is living here, too hard to recover from and too easy to drive adaptation.
• Zone 4 (80-90%): lactate threshold. Short sentences only. Raises the pace you can hold for a long time. The 10K and half-marathon zone.
• Zone 5 (90-100%): VO2 max and neuromuscular. Minutes at a time at most. Top-end speed and maximal oxygen uptake.

Estimating maximum heart rate

The classic MHR = 220 − age is still everywhere and it is not very good: it overestimates the young and underestimates the old, with a standard deviation around 10 beats. Tanaka’s MHR = 208 − (0.7 × age) fits the population better and is the default here. Neither beats an actual measurement from a hard field test, so if you have a real number, use it.

Worked example

A 35-year-old, Tanaka maximum 184 bpm, resting 55 bpm. Heart rate reserve is 129.

Zone 2 by heart rate reserve: 55 + 0.60 × 129 = 132 bpm at the bottom, 55 + 0.70 × 129 = 145 at the top. Zone 4: 55 + 0.80 × 129 = 158 to 55 + 0.90 × 129 = 171.

The same zones as bare percentages of maximum would read 110 to 129 and 147 to 166. If you have ever wondered why easy runs feel so slow when you follow a watch’s default zones, this gap is usually why.

Your data stays in your browser. We do not store, collect, or transmit any information you enter.