Cycling Heart Rate Zone Calculator

Heart rate zones are typically calculated as percentages of your maximum heart rate (MHR). The standard method defines five zones ranging from roughly 50–60% (Zone 1) up to 90–100% (Zone 5) of max HR. The Karvonen method refines this by factoring in your resting heart rate, producing a Heart Rate Reserve (HRR) calculation that is more personalised to your fitness level.

The simplest estimate is the formula 220 minus your age. However, this is only an approximation — individual max HR can vary by 10–20 bpm. A more accurate method is a field test: after a thorough warm-up, complete 2–3 hard 3-minute efforts near your absolute limit, recording the highest HR you reach. Using a measured max HR gives you much more precise training zones.

The Karvonen (Heart Rate Reserve) method calculates zones based on the range between your resting HR and your max HR. Because it accounts for your cardiovascular fitness baseline, it generally produces more accurate training zones than a simple percentage of max HR — especially for well-trained cyclists with a low resting heart rate.

Zone 2 (aerobic base, roughly 60–70% of max HR) is the cornerstone of endurance cycling training. Riding in Zone 2 builds mitochondrial density, improves fat oxidation, and develops the aerobic engine needed for long rides. Most coaches recommend that 60–80% of your total weekly training volume be in Zone 2 for long-term performance development.

Zone 4 corresponds to riding near your lactate threshold — the intensity at which lactate begins to accumulate faster than it can be cleared. This is roughly 80–90% of max HR and feels like a hard, sustainable effort for 20–60 minutes. Threshold intervals in Zone 4 are among the most effective sessions for improving cycling time trial and race performance.

A common approach is the 80/20 polarised model: around 80% of training volume at low intensity (Zones 1–2) and 20% at high intensity (Zones 4–5), with limited time in Zone 3. Zone 5 work (VO2 max intervals) is highly effective but stressful, so it is typically reserved for specific build phases and limited to 1–2 sessions per week.

Yes — heart rate zones are equally valid for indoor cycling and turbo trainer workouts. Note that heart rate can run slightly higher indoors due to heat and lack of airflow, so ensure good ventilation. Many indoor cyclists also combine HR zones with power zones, using HR as a secondary guide to check that perceived effort aligns with actual physiological load.

Different calculators use different zone models. Some use a 5-zone system, others use 6 or 7 zones. The percentage boundaries also vary by model — for example, Coggan, British Cycling, and Joe Friel all define zones slightly differently. The most important thing is to pick one consistent system and stick to it throughout your training season.