HomeAll ToolsAboutBlog
Cardio & Running

Heart Rate Zone Calculator

Find your 5 heart rate training zones based on your maximum heart rate — and know exactly what to aim for in every workout.

Heart Rate Zone Calculator

5-zone model · Karvonen method

Heart rate zones segment your training intensity into meaningful bands. Each zone trains a different energy system — from fat-burning low-intensity work (Zone 2) to VO2 max development intervals (Zone 5). Knowing your zones prevents you from always training in the "grey zone" — too hard for recovery adaptation, too easy for performance gains.

Max HR estimate (Fox formula): 220 - age. For accuracy, use a real max HR test or field test value.

The 5 Training Zones Explained

Zone% Max HRFeelPurpose
Zone 150–60%Very easyRecovery, warm-up
Zone 260–70%ConversationalAerobic base, fat oxidation
Zone 370–80%Moderate effortAerobic capacity, tempo
Zone 480–90%Hard, breathing laboredLactate threshold, race pace
Zone 590–100%Maximum effortVO2 max, speed

80/20 Rule of Training

Elite endurance athletes spend ~80% of training time in Zone 1–2 and only ~20% at higher intensities. Most recreational athletes invert this accidentally — training mostly at moderate intensity, which is metabolically tiring but doesn't produce the best aerobic adaptations.

Frequently Asked Questions

Zone 2 (60–70% max HR) is the intensity at which your body primarily uses fat as fuel and where mitochondrial density adaptations occur. Long Zone 2 sessions are the foundation of all elite endurance training. Most recreational athletes under-invest here — spending too much time at moderate intensities (Zone 3) that are metabolically expensive but don’t produce the same aerobic base adaptations.
The most reliable field test: run hard for 3–5 minutes, then sprint the final 30–60 seconds at absolute maximum effort. Your max HR at the end is your actual MHR. The 220-age formula is accurate to within ±10–15 bpm for most people. If this estimate feels off during hard efforts, use a field test value instead.
The Karvonen method calculates Heart Rate Reserve (HRR = max HR - resting HR) and then applies zone percentages to this reserve rather than max HR alone. This is more precise because it accounts for your resting HR, which changes with fitness. Add your resting HR back at the end: Zone % of HRR + resting HR = target HR.
Following the 80/20 principle: for 5 training days/week, aim for 4 days Zone 1–2 and 1 day at Zone 4–5 (intervals or tempo). Zone 5 should be used sparingly (1–2x/week max) because it requires 48–72 hours for full recovery. Overloading high zones is the primary cause of overtraining and stagnation.

Related Calculators

Max Heart Rate CalculatorEstimate your true maximum heart rate using multiple formulas.Calculate MHR → VO2 Max CalculatorEstimate your aerobic capacity from performance data.Calculate VO2 Max → Running Pace CalculatorConvert pace, time, and distance for any run.Calculate Pace → Recovery Heart Rate CalculatorTest your cardiac fitness from post-exercise heart rate drop.Calculate →