Heart Rate Training Zones Explained (Karvonen Method)

Not all cardio is created equal. A slow jog and an all-out sprint both raise your heart rate, but they train completely different systems. Heart rate zones give you the precision to train with purpose.

The Karvonen formula

Unlike the simple percentage-of-max method, Karvonen accounts for your resting heart rate, making it more personalized:

Target HR = ((Max HR − Resting HR) × % Intensity) + Resting HR

Where:
  Max HR = 220 − age (simple estimate)
  Or: 208 − (0.7 × age) (more accurate for active adults)
  Resting HR = measured first thing in the morning

The 5 training zones

Zone	Intensity	Karvonen %	Purpose
Zone 1	Very light	50–60%	Recovery, warm-up
Zone 2	Light	60–70%	Fat burning, base endurance
Zone 3	Moderate	70–80%	Aerobic fitness, stamina
Zone 4	Hard	80–90%	Anaerobic threshold, speed
Zone 5	Maximum	90–100%	VO2 max, sprint power

Worked example

Age 35, resting heart rate 62 bpm:

Max HR = 220 − 35 = 185 bpm
Heart Rate Reserve (HRR) = 185 − 62 = 123 bpm

Zone 2 (60–70%):
  Lower: (123 × 0.60) + 62 = 73.8 + 62 = 136 bpm
  Upper: (123 × 0.70) + 62 = 86.1 + 62 = 148 bpm

Zone 4 (80–90%):
  Lower: (123 × 0.80) + 62 = 98.4 + 62 = 160 bpm
  Upper: (123 × 0.90) + 62 = 110.7 + 62 = 173 bpm

Why Zone 2 gets all the hype

Zone 2 training (conversational pace) builds your aerobic base:

• Increases mitochondrial density
• Improves fat oxidation efficiency
• Builds capillary networks in muscles
• Low injury risk, high recovery
• Elite endurance athletes spend 80% of training here

When to use each zone

• Easy runs / active recovery: Zone 1–2
• Long runs / base building: Zone 2
• Tempo runs / race pace: Zone 3–4
• Intervals / hill sprints: Zone 4–5
• Max effort testing: Zone 5

Tips for heart rate training

• Measure resting HR for 5 mornings and average them
• The 220-minus-age formula has a ±10–12 bpm error margin
• Chest straps are more accurate than wrist-based optical sensors
• Caffeine, heat, and dehydration artificially inflate heart rate
• Cardiac drift (HR rising during steady effort) is normal after 45+ minutes
• Train polarized: 80% easy (Zone 1–2) and 20% hard (Zone 4–5)

Calculate your personal zones with OurDailyCalc’s heart rate zone calculator — enter your age and resting heart rate for instant Karvonen-based targets.

TL;DR

• Karvonen formula uses resting HR for personalized zones
• 5 zones from recovery (50%) to max effort (100%)
• Zone 2 builds aerobic base — where most training should live
• 80/20 rule: 80% easy, 20% hard for optimal fitness gains
• Measure resting HR in the morning for accuracy