Heart Rate Zone Calculator

What Are Heart Rate Zones?

Heart rate training zones divide your exercise intensity into five levels based on percentages of your maximum heart rate. Zone 1 (50–60%) is very light activity like walking. Zone 2 (60–70%) is moderate effort – conversational pace running or brisk walking. Zone 3 (70–80%) is aerobic conditioning where breathing becomes heavier. Zone 4 (80–90%) is the threshold zone where sustained effort is difficult. Zone 5 (90–100%) is maximum effort that can only be maintained for short intervals.

How to Estimate Your Max Heart Rate

The simplest estimation is 220 minus your age. A 35-year-old has an estimated max heart rate of 185 bpm. This formula is a rough average and can be off by 10–15 bpm in either direction. The Tanaka formula (208 – 0.7 × age) is considered slightly more accurate. The most reliable method is a supervised graded exercise test, but for most recreational exercisers, the age-based estimate provides a practical starting point for zone training.

Training Benefits of Each Zone

Zone 2 is where most of your weekly exercise should happen. It builds aerobic base, improves fat metabolism, and supports recovery without excessive fatigue. Zone 3 improves aerobic capacity and is the effort level of steady-state cardio. Zone 4 training raises your lactate threshold – the point at which fatigue accumulates rapidly. Zone 5 intervals improve VO2 max and peak power output. A well-structured training week includes roughly 80% of time in Zones 1–2 and 20% in Zones 3–5.

Using a Heart Rate Monitor

Chest strap monitors are the most accurate for real-time heart rate tracking. Wrist-based optical sensors on smartwatches work well at steady paces but can lag during intervals and miss rapid changes. For zone training, accuracy within 3–5 bpm is acceptable. Check your resting heart rate first thing in the morning for a baseline – lower resting heart rate generally indicates better cardiovascular fitness. A sudden rise in resting HR may signal overtraining, illness, or inadequate recovery.

Frequently asked questions