Heart Rate Zones Calculator

The Five Zone Convention

Heart rate zones divide the range between rest and maximum into bands, most often five of them. A common layout places zone one at 50 to 60 percent of maximum for recovery, zone two at 60 to 70 for easy aerobic work, zone three at 70 to 80 for steady tempo, zone four at 80 to 90 for hard effort, and zone five above 90 for short maximal bursts.

These boundaries are a convention, not a law of physiology. Laboratories often define zones from lactate or ventilatory thresholds instead, and those personal breakpoints can land above or below the percentage bands. The percentages are simply an accessible approximation when no lab data is available.

Using the Zones Well

The value of zones is that they name intensities so a plan can balance them. Most endurance work belongs in the lower zones, where the body adapts without excessive fatigue, while the upper zones are used sparingly to sharpen speed and power. If your estimated maximum is off, every band shifts with it, so a tested maximum makes the whole system more trustworthy.