What heart rate zones are for
Heart rate zones split your effort range into five bands, from gentle recovery to all-out. Each band trains something slightly different: low zones build your aerobic base and help you recover, high zones raise your lactate threshold and VO2 max.
The biggest practical benefit is honesty. Most people run or cycle their easy sessions too hard and their hard sessions too easy, and end up stuck in the middle. A number on a watch makes that obvious.
How to use the calculator
Enter your age. The calculator estimates your maximum heart rate with the Tanaka formula by default, or with the classic 220 minus age if you choose it.
Then, if you can, add your resting heart rate. With it, the calculator uses the Karvonen method, which builds each zone on your heart rate reserve rather than a flat percentage of maximum. Without it, zones are simple percentages of your estimated max. If you have tested your real maximum in a supervised or field test, that is always better than any age formula.
The formulas
Max HR (Tanaka) = 208 − 0.7 × age
Max HR (classic) = 220 − age
Heart rate reserve (HRR) = max HR − resting HR
Karvonen target = resting HR + (HRR × intensity %)
Percent-of-max target = max HR × intensity %
Tanaka's 2001 analysis of hundreds of studies found that 220 minus age underestimates max heart rate in older adults. The two agree at age 40 (180 bpm) and drift apart above and below it.
Karvonen tends to give higher, more individual numbers for fit people. Someone with a resting rate of 50 bpm has more reserve than someone at 75, so their zones sit differently even at the same age.
The five zones
| Zone | Intensity | Feels like | Main purpose |
|---|---|---|---|
| Zone 1 | 50-60% | Very easy, chatty | Recovery and warm-ups |
| Zone 2 | 60-70% | Easy, can hold a conversation | Aerobic base, fat oxidation, endurance |
| Zone 3 | 70-80% | Moderate, short sentences | Aerobic fitness, tempo work |
| Zone 4 | 80-90% | Hard, a few words at a time | Lactate threshold, race pace |
| Zone 5 | 90-100% | Maximal, no talking | VO2 max, short intervals |
A 35-year-old with a resting rate of 60 bpm has a Tanaka max of about 184 bpm and a reserve of 124. Their zone 2 by Karvonen is 60 + 124 × 0.6 to 0.7, or roughly 134-147 bpm.
Why zone 2 is everywhere right now
Zone 2 training has become popular well beyond endurance sport, and with reason. Long, easy sessions improve the ability of your muscles to use fat and clear lactate, build mitochondria and strengthen the heart, with little recovery cost.
Many endurance coaches have long used roughly an 80/20 split: around 80% of training time at low intensity and 20% hard. For lifters, two or three 30-45 minute zone 2 sessions per week improve work capacity between sets without eating into strength. The HIIT vs LISS guide covers how to fit it around a lifting plan.
A quick check for zone 2: you can breathe through your nose and speak in full sentences, but you would not want to sing.
How to measure resting heart rate
- Measure first thing in the morning, before getting up or drinking coffee.
- Find your pulse at the wrist or neck, or use a chest strap.
- Count beats for 60 seconds, or 30 seconds and double it.
- Repeat on three to five mornings and use the average.
Most adults sit between 60 and 100 bpm, and trained endurance athletes often fall below 60. A resting rate several beats above your usual can be a sign of poor sleep, illness or under-recovery, which is covered in the recovery guide.
Using zones alongside lifting
Most people reading this train with weights first and do cardio second. Heart rate zones still help, but the goal shifts from racing performance to fitness, recovery and fat loss without hurting strength.
- Keep most cardio in zone 2. It builds the aerobic base that speeds recovery between sets and barely touches leg recovery.
- Limit zone 4-5 work to one or two short sessions a week. Hard intervals are effective but taxing; stack them on the same day as upper-body lifting, or well away from heavy squats and deadlifts.
- Use zone 1 for active recovery. A 20-minute easy walk or bike ride on a rest day can reduce stiffness without adding fatigue.
- Separate cardio and lifting by at least a few hours when you can, or do cardio after lifting so it does not tire you before heavy sets.
Heart rate during lifting itself is a poor guide to effort. A set of heavy squats can push heart rate into zone 4 for a minute, then it falls during rest. That is normal and does not mean the session counts as cardio.
Zones also shift as you get fitter. Your resting heart rate will often drop by several beats over the first few months of regular cardio, which raises your heart rate reserve. Re-measure your resting rate every couple of months and recalculate so your zones stay accurate.
Limitations
Age formulas predict the average, and individuals can differ from them by 10-15 bpm or more. If your zones feel wrong, trust your breathing and perceived effort and adjust. Wrist-based optical sensors lag and misread during intervals and lifting, so a chest strap is more reliable for hard efforts.
Beta blockers and some other medications lower heart rate and make these zones inaccurate. If you have a heart condition, are pregnant or are new to exercise after a long break, ask your doctor what intensity is appropriate before training in zones 4 and 5.
Frequently asked questions
Which max heart rate formula should I use?
Tanaka (208 minus 0.7 times age) is more accurate across age groups, especially for people over 40. 220 minus age is simpler and widely used. A real field test beats both.
Is the Karvonen method better?
For most people, yes. It accounts for your resting heart rate, so fitter people with low resting rates get zones that match their actual reserve instead of a generic percentage.
What zone burns the most fat?
Zone 2 burns the highest proportion of fat, but higher zones burn more total calories per minute. For fat loss, total weekly energy balance matters far more than the zone you train in.
Why is my heart rate higher than usual during workouts?
Heat, dehydration, caffeine, stress, poor sleep and illness all raise heart rate at the same pace. If it stays elevated for days, take an easier week.
How much time should I spend in each zone?
A common approach is roughly 80% of cardio time in zones 1-2 and 20% in zones 3-5. Beginners can do almost everything in zone 2 for the first couple of months.
References
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001.
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Ann Med Exp Biol Fenn. 1957.
- Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. 2010.
Results are estimates for healthy adults and are not medical advice. See our medical disclaimer.
