Zone 2 Heart Rate Calculator

Zone 2 training refers to exercising at a low-to-moderate intensity — typically 60–70% of your maximum heart rate — where your body primarily burns fat for fuel and builds aerobic base fitness. It's the cornerstone of endurance training used by elite athletes and is sustainable for long durations without excessive fatigue.

The most widely used formula is MHR = 220 − Age, established by the American Heart Association. While simple, it's an estimate — individual MHR can vary by 10–20 bpm from this prediction. For greater accuracy, you can enter a measured maximum heart rate (e.g. from a lab test or all-out effort) directly into this calculator.

The Karvonen formula accounts for your Heart Rate Reserve (HRR = MHR − Resting HR), which reflects your cardiovascular fitness level. The target zone is calculated as: THR = [(MHR − RHR) × %Intensity] + RHR. Because it personalizes the range to your resting HR, it tends to produce more individualized and effective training zones than the basic age-only method.

Measure your resting heart rate first thing in the morning before getting out of bed. Count your pulse for 60 seconds (or 30 seconds and double it). Most adults have a resting HR between 60–80 bpm, while well-trained endurance athletes can be 40–55 bpm. A lower resting HR generally indicates better cardiovascular fitness.

Zone 1 (50–60% MHR) is active recovery — very light effort. Zone 2 (60–70% MHR) is the aerobic base zone — comfortable, conversational pace. Zone 3 (70–80% MHR) is aerobic development — moderate effort. Zone 4 (80–90% MHR) is lactate threshold — hard, unsustainable for long periods. Zone 5 (90–100% MHR) is maximum effort — sprint intervals and all-out work.

Most endurance coaches and sports scientists recommend spending 70–80% of total training volume in Zone 2. This polarized approach — mostly easy with some high-intensity work — has been shown to improve endurance performance more effectively than training at moderate intensities all the time.

Yes — heart rate zones apply to any aerobic activity. However, note that maximum heart rate can differ slightly between sports due to body position and muscle mass recruited. Cyclists often record slightly lower max HRs than runners, and swimmers even lower. For sport-specific precision, use a measured MHR from that activity rather than the age-based formula.

Zone 2 feels like a comfortable, conversational pace — you should be able to speak in full sentences without gasping. Many beginners find true Zone 2 surprisingly slow at first, especially when running. Using a heart rate monitor is the most reliable way to confirm you're staying within the zone rather than relying on perceived effort alone.