Zone 2 Heart Rate by Age:
How Wrong Is Yours?

Zone 2 Heart Rate by Age: The Reference Table

Below is the standard Zone 2 heart rate chart based on the 220-minus-age formula (60–70% of estimated max HR). The "Actual Possible Range" column shows how wide your real Zone 2 could be when you account for the ±15 bpm individual variation in max heart rate.

Age	Formula Zone 2	Actual Possible Range
25	117 – 137 bpm	108 – 147 bpm
30	114 – 133 bpm	105 – 144 bpm
35	111 – 130 bpm	102 – 140 bpm
40	108 – 126 bpm	99 – 137 bpm
45	105 – 123 bpm	96 – 133 bpm
50	102 – 119 bpm	93 – 130 bpm
55	99 – 116 bpm	90 – 126 bpm
60	96 – 112 bpm	87 – 123 bpm
65	93 – 109 bpm	84 – 119 bpm
70	90 – 105 bpm	81 – 116 bpm

Why the 220-Minus-Age Formula Fails

The formula was published by Fox et al. in 1971 based on aggregated data — not a rigorous study. It describes a population trend, not individual physiology. A large-scale analysis by Tanaka et al. (2001) proposed a more accurate formula (208 - 0.7 × age), but even that has a standard deviation of ±10 bpm.

The core problem: no formula based on age alone can account for genetics, fitness level, training history, medication, sleep, or stress — all of which affect your actual max heart rate and your aerobic threshold.

What Happens When You Train in the Wrong Zone

Training just 10 bpm above your real Zone 2 puts you in Zone 3 — the grey zone. Zone 3 feels like you're working. You sweat. Your heart rate is elevated. But you're not building the mitochondrial density or fat oxidation that makes Zone 2 training so powerful for longevity. You're grinding without adapting.

Training 10 bpm below your real Zone 2 means you're barely stressing your aerobic system. You're getting fresh air and little else. The adaptation signal is too weak to trigger meaningful change.

How Zone2AI Solves This

Zone2AI doesn't use the 220-minus-age formula. It reads your actual biometric data from Apple Health — your true max heart rate from real workouts, your resting heart rate, your VO2 max — and calculates a personalized Zone 2 range using the Karvonen (Heart Rate Reserve) method.

After every workout, it asks how the effort felt and adjusts your zones accordingly. The longer you use it, the more accurate your Zone 2 becomes. It's the closest thing to a lactate test you can get without going to a lab.