What are heart rate zones?
Heart rate zones are ranges (as a percentage of your maximum heart rate) that each train your body differently. Staying in the right zone for your goal — whether that's burning fat, building endurance, or boosting speed — makes your cardio far more effective than just "going hard".
The 5 zones explained
- Zone 1 · 50–60% — Recovery: very easy, warm-ups and cool-downs.
- Zone 2 · 60–70% — Fat burn / endurance: the base-building sweet spot; you can still hold a conversation.
- Zone 3 · 70–80% — Aerobic: improves cardiovascular fitness and stamina.
- Zone 4 · 80–90% — Threshold: hard; raises your lactate threshold and speed.
- Zone 5 · 90–100% — Maximum: all-out intervals, short bursts only.
What is the Karvonen method?
The Karvonen formula uses your heart rate reserve (max HR minus resting HR) to set zones, which accounts for your fitness level. Target = ((Max HR − Resting HR) × intensity%) + Resting HR. Fitter people with lower resting rates get more accurate, personalised zones.
How do I find my resting heart rate?
Measure your pulse for 60 seconds first thing in the morning before getting out of bed, ideally across a few days.
Which zone burns the most fat?
Zone 2 burns the highest share of calories from fat, but higher zones burn more total calories. Most training plans mix zones.