Fat Burning Zone Calculator
Find your personal fat-burning heart rate zone (60–70% of HRmax). Zone 2 is where the highest percentage of calories comes from fat oxidation.
What the "Fat-Burning Zone" Really Is
The fat-burning zone is the intensity band (roughly 60–70% HRmax, corresponding to Zone 2) where the highest percentage of your energy comes from fat oxidation. It is not the zone that burns the most fat calories in absolute terms — higher-intensity work burns more total calories, and a proportional share of those is still fat.
FATmax — The Individual Fat-Oxidation Peak
Sport scientists use the term FATmax to describe the exercise intensity at which an individual's fat oxidation is maximised. In lab studies using indirect calorimetry, FATmax falls between 55% and 72% of VO₂max for most adults, with trained endurance athletes able to sustain higher fat oxidation rates and at higher relative intensities than untrained subjects.
Reference: Achten J, Jeukendrup AE. Maximal fat oxidation during exercise in trained men. International Journal of Sports Medicine. 2003;24(8):603–8.
Fat Oxidation Rates: Trained vs Untrained
| Group |
Peak fat oxidation |
Occurs at |
| Sedentary adult | 0.2–0.4 g/min | ~50% VO₂max |
| Recreationally trained | 0.4–0.6 g/min | ~60% VO₂max |
| Highly trained endurance | 0.7–1.0 g/min | ~65–72% VO₂max |
Should You Actually Care About the Fat-Burning Zone?
If your goal is body composition, focus on weekly energy balance and total training volume — the zone breakdown matters less. If your goal is endurance performance (marathon, gran fondo, triathlon), improving fat oxidation is genuinely important: better fat metabolism spares glycogen and pushes back the point at which you "bonk." That is the real reason serious endurance athletes prioritise Zone 2.
Heart Rate Zones (reference: age 30, HRmax ≈ 187 bpm, Tanaka)
| Zone |
Name |
% HRmax |
BPM (age 30) |
Primary use |
| 1 | Recovery | 50–60% | 94–112 | Warm-up, recovery, active rest |
| 2 | Endurance | 60–70% | 112–131 | Aerobic base, fat oxidation |
| 3 | Aerobic | 70–80% | 131–150 | Tempo, aerobic capacity |
| 4 | Threshold | 80–90% | 150–168 | Lactate threshold intervals |
| 5 | Maximum | 90–100% | 168–187 | VO₂ max, neuromuscular power |
What Each Zone Feels Like (Talk Test)
- Zone 1 · Recovery: You can sing.
- Zone 2 · Endurance: You can hold a full conversation.
- Zone 3 · Aerobic: Speaking becomes noticeably harder.
- Zone 4 · Threshold: Only short phrases of a few words.
- Zone 5 · Maximum: Almost impossible to speak.
Frequently Asked Questions
How accurate are heart rate calculators?
Formula-based calculators typically estimate HRmax within ±10–15 bpm. They are accurate enough to structure training for recreational athletes but not a substitute for a supervised max test.
What is the Karvonen method?
Karvonen uses heart rate reserve (HRR = HRmax − HRrest). Target HR = HRrest + (Intensity% × HRR). It personalises zones by accounting for resting heart rate.
Should I use different zones for cycling vs running?
Your bpm targets stay the same, but heart rate response differs by sport. Cycling HR is typically 5–10 bpm lower than running at equivalent perceived effort due to the seated position.
Is Zone 2 the best zone for fat loss?
Zone 2 maximises the percentage of calories from fat, but higher intensities burn more total calories per minute. Long-term fat loss is driven by total weekly energy balance.
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