What Is My Heart Rate Zone 2? Calculate Yours Now
Zone 2 heart rate is moderate aerobic exercise at 60–70% of your maximum heart rate. For a 40-year-old that is roughly 108–126 bpm; for a 30-year-old, 114–133 bpm. This guide compares the three main calculation methods and shows how to structure Zone 2 into your week.
How to Calculate Your Zone 2 Heart Rate
- 220 − age (Fox): Fast and popular, but ±10–12 bpm variability. A 40-year-old: Zone 2 ≈ 108–126 bpm.
- Tanaka (208 − 0.7 × age): More accurate for adults over 40. A 50-year-old: HRmax ≈ 173 bpm.
- Karvonen (uses resting HR): Zone 2 = (HRmax − HRrest) × 0.60–0.70 + HRrest. A 40-year-old with HRmax 180 and HRrest 55 gets 130–143 bpm — a personalized range that shifts with fitness.
Why Zone 2 Works: The Physiology
Zone 2 sits just below the lactate threshold. Consistent training in this range increases mitochondrial density in slow-twitch muscle fibers, improves fat oxidation, and produces eccentric cardiac hypertrophy — the heart chambers enlarge and stroke volume rises. Trained endurance athletes often see resting heart rates in the low 40s as a result.
How to Verify You Are in Zone 2
- Talk test: full sentences yes, singing no.
- RPE ≈ 4/10: steady, sustainable, not comfortable.
- Watch for HR drift on longer sessions — heat and fatigue push HR up at the same pace.
- Use walk breaks when HR climbs above the ceiling. Not a failure — a legitimate reset tool.
Structuring Zone 2 Into Your Week
Follow the polarized 80/20 model: ~80% of weekly training in Zone 2, ~20% in Zones 4–5. Aim for 3–5 sessions per week of 45–90 minutes each. Track pace or power at the same heart rate over weeks — when you go faster at the same Zone 2 HR, your aerobic base is growing.
Zone 2 FAQ
What is Zone 2 heart rate as a percentage of max?
60–70% of your maximum heart rate.
How do I find Zone 2 without a monitor?
Use the talk test and target RPE 4/10.
Is Karvonen better than 220 − age?
Yes — it personalizes the range using resting heart rate.
How long should a Zone 2 session last?
45–90 minutes maximizes mitochondrial adaptation.
Does Zone 2 burn fat?
Higher fat percentage per minute than harder work, but total energy balance drives body composition.
SnapHRZones — Heart Rate Zone Calculator · Guides · FAQ · About
This page requires JavaScript for the interactive calculator. Enable JavaScript for personalised results.