Fat Burning Zone Calculator
Work out your fat-burning heart-rate zone — the 60–70% band where fat supplies the largest share of the calories you burn — from your age, with an optional Karvonen method anchored to your resting heart rate.
Fat-burning zone
102–119 bpm
- Estimated max heart rate
- 170 bpm
- Lower bound (60% of max heart rate)
- 102 bpm
- Upper bound (70% of max heart rate)
- 119 bpm
The fat-burning zone is the 60–70% band — Zone 2 of the standard five-zone model. Fat supplies the largest share of calories here, but harder efforts burn more total calories per minute. Max heart rate is an age-based estimate; individual values vary by ±10 bpm or more.
How to use this calculator
Enter your age and pick a max heart rate formula — 220 − age is the familiar classic; 208 − 0.7 × age (Tanaka) is the better-validated research formula, especially past age 40. Then choose a zone method. "% of max heart rate" needs nothing else and gives the fat-burning band most fitness charts and cardio machines show. "Heart-rate reserve (Karvonen)" also uses your resting heart rate — measured before getting out of bed — and anchors the band to it, which personalises the range to your fitness level. The result panel shows your fat-burning zone as a bpm range, along with your estimated max heart rate and both bounds.
How the calculation works
Your maximum heart rate is estimated from age: 220 − age (Fox, 1971) or 208 − 0.7 × age (Tanaka, 2001). The fat-burning zone is then the 60–70% band — the same band as Zone 2 in the standard five-zone training model. At this light, sustainable intensity your body draws the largest proportion of its fuel from fat; push harder and total calorie burn rises but the fat share falls as carbohydrate takes over. With the %-of-max method the band is a straight percentage of max heart rate; with the Karvonen method the percentages apply to your heart-rate reserve — max minus resting — and are added back on top of resting, which places the same band higher on the bpm scale. Laboratory studies locate peak fat oxidation near 74% of max heart rate on average, with wide individual spread, so treat the 60–70% convention as a practical guide rather than a personal measurement.
Worked example
A 50-year-old using 220 − age has an estimated max heart rate of 170 bpm. The fat-burning zone is 60–70% of that: 0.60 × 170 = 102 bpm and 0.70 × 170 = 119 bpm, so the range is 102–119 bpm — a brisk walk, easy jog or steady bike ride for most people. Switching to the Karvonen method with a resting heart rate of 60 bpm gives a heart-rate reserve of 170 − 60 = 110 bpm, and the same band becomes 60 + 0.60 × 110 = 126 bpm to 60 + 0.70 × 110 = 137 bpm — noticeably higher, because the reserve method anchors the zone to your resting rate.
Frequently asked questions
What is the fat-burning zone?
It is the conventional name for exercise at roughly 60–70% of your maximum heart rate — the same band as Zone 2 in the five-zone training model. At this intensity your muscles draw the largest proportion of their fuel from fat rather than carbohydrate, and the effort is light enough to sustain for a long time: think brisk walking, easy jogging or steady cycling where you can still talk in full sentences. The name describes the fuel mix during the session, not a special mechanism for losing body fat.
Do I actually burn the most fat in the fat-burning zone?
You burn the highest proportion of calories from fat there, but not necessarily the most fat overall. Total calorie burn rises with intensity, so a harder session can burn more absolute fat per minute even though fat makes up a smaller share of it — as an illustration, 30 minutes of easy effort might burn around 200 kcal with half from fat, while 30 minutes of hard effort might burn around 400 kcal with a third from fat: more fat calories in total. The fat-burning zone wins on sustainability, not on per-minute fat burn: you can stay in it far longer and recover from it faster.
What does the research say about the best fat-burning intensity?
Laboratory studies measure the intensity of maximal fat oxidation — called Fatmax — with a graded exercise test and indirect calorimetry. A frequently cited study in moderately trained cyclists (Achten, Gleeson and Jeukendrup, 2002) found peak fat oxidation at 64% of VO2max, corresponding to about 74% of maximum heart rate, with fat oxidation staying high across a broad zone either side of the peak. Individual results vary widely with fitness, diet and training history, so the consumer 60–70% band is a reasonable heuristic that sits slightly below the average lab-measured peak — if the exact number matters to you, only a metabolic test can find your personal Fatmax.
Is the fat-burning zone the same as Zone 2?
Numerically yes — both are the 60–70% band of maximum heart rate in the standard five-zone model, so this calculator and a Zone 2 target give you the same bpm range. The difference is framing: "Zone 2" language comes from endurance training, where the band is prized for building aerobic base with minimal fatigue, while "fat-burning zone" language comes from gym cardio charts and describes the fuel mix. If you want all five zones rather than just this band, use our heart rate zone calculator.
Will training in the fat-burning zone make me lose weight?
Only if it helps you maintain a calorie deficit — weight loss is governed by calories in versus calories out over weeks, not by which fuel your muscles favour during a workout. Burning more fat during a session does not mean more fat loss overall, because fuel use rebalances across the rest of the day. What the zone genuinely offers is exercise that is comfortable enough to do often and for long stretches, which makes it easier to accumulate a meaningful weekly calorie burn and stick with it. Pair it with our calories burned and TDEE calculators to see the energy-balance picture.
Should I use the %-of-max or the Karvonen method?
The %-of-max method matches the charts printed on cardio machines and most fitness articles, and needs only your age. The Karvonen method also uses your resting heart rate and applies the 60–70% band to your heart-rate reserve (max minus resting), which places the zone higher in bpm — in the worked example above, 126–137 bpm instead of 102–119 bpm for the same person. Because it credits a low resting heart rate, Karvonen personalises the band to your fitness level and tracks physiological effort more closely; if you know your true resting heart rate from a few morning measurements, it is the better choice. Whichever you pick, stay consistent so your sessions are comparable.