Heart Rate Zones Calculator (Karvonen)

About this tool

Karvonen HRR 5-zone method

Heart rate training zones calculator using the Karvonen Heart Rate Reserve method with your actual resting HR. The most accurate zone-based prescription for cardio training.

RT-HLT-053 · Health & Fitness

Age (years)

Resting HR (bpm)

Max HR (override, 0 = use Tanaka)

⚠ Disclaimer: FOR FITNESS AND EDUCATIONAL PURPOSES ONLY. NOT MEDICAL ADVICE. These calculations are based on population-average formulas and may not reflect your individual physiology. Consult a physician before beginning any exercise programme, especially if you have cardiovascular conditions, pregnancy, or other medical concerns. Heart rate, body composition, and metabolic estimates from this tool are not substitutes for direct medical measurement.

Max HR (Tanaka)

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Resting HR

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HR Reserve

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5 Karvonen training zones

Zone + purpose	% HRR	Range

How to use the HR zones calculator

Find your resting heart rate

Measure your RHR first thing in the morning before getting up, lying still for 1-2 minutes. Use a fitness tracker, smartwatch, or finger-on-wrist count for 60 seconds. Untrained adults: 60-80 bpm. Recreational athletes: 50-65. Elite endurance athletes: 35-50.

Enter age

Age in years. The calculator uses Tanaka 2001 (208 − 0.7 × age) by default. To override with your tested max HR from a field test or treadmill stress test, enter it in the override field.

(Optional) Override max HR with tested value

If you've done a max-effort field test (1-mile all-out run, treadmill ramp test, or sprint test) and observed a higher peak HR than Tanaka predicts, enter it. Otherwise leave at 0 and Tanaka 2001 is used.

Read the 5 zones

Z1 (50-60%): recovery + warm-up. Z2 (60-70%): aerobic base — most weekly miles. Z3 (70-80%): tempo / marathon pace. Z4 (80-90%): lactate threshold / 10K pace. Z5 (90-100%): VO2 max intervals.

Apply polarised training

Modern endurance theory (Seiler 2010): spend ~80% of weekly volume in Zone 1-2, ~20% in Zone 4-5, minimal time in Zone 3 ("junk miles"). This builds aerobic base + top-end power without the moderate-intensity grind that produces fatigue without optimal adaptation.

Karvonen zones — using YOUR baseline, not a generic chart

Most gym wall posters give you heart rate zones as percentages of "220 minus age". That\'s a percentage-of-max-HR method — easy to compute but ignores individual aerobic baseline. A 40-year-old endurance athlete with resting HR 45 and a 40-year-old sedentary office worker with resting HR 85 both share the same predicted max HR (180), but their actual training zones are wildly different. The athlete\'s Zone 2 should be around 126-140 bpm (60-70% of HRR + RHR); the office worker\'s Zone 2 is 142-152 bpm. The Karvonen Heart Rate Reserve (HRR) method, published in 1957 by Finnish physiologist M.J. Karvonen, captures this difference. Modern wearables (Garmin, Polar, Apple Watch, Whoop) all default to Karvonen-based personalised zones.

The HRR formula

Karvonen: Target HR = RHR + (MaxHR − RHR) × intensity%. Example: 40-year-old, MaxHR 180 (Tanaka), RHR 60. HRR = 120. Zone 2 (60-70%): RHR + 0.60 × 120 to RHR + 0.70 × 120 = 132 to 144 bpm. Compare to the percentage-of-max-HR method (60-70% of 180): 108-126 bpm — much lower. The HRR method better captures the working-heart-rate range. Both methods are widely used; Karvonen is the more accurate one when you have a reliable RHR measurement.

Karvonen\'s 1957 paper introduced the idea that "heart rate reserve" matters more than absolute heart rate. Modern wearables make this trivial to compute — but only if you measure RHR accurately.

The 5-zone system + polarised training

Modern endurance science recognises 5 zones. Zone 1 (50-60% HRR) is true active recovery — easy enough to converse easily. Zone 2 (60-70%) is the aerobic base where mitochondrial density develops; the foundation of long-term endurance fitness. Zone 3 (70-80%) is "tempo" or marathon pace — sustainable hard. Zone 4 (80-90%) is lactate threshold, the 10K race pace. Zone 5 (90-100%) is VO2 max intervals, 3-5 minute repeats. Polarised training (Seiler 2010): elite endurance athletes spend ~80% of training time in Zones 1-2, ~20% in Zones 4-5, with minimal Zone 3. The "moderate-intensity sweet spot" is actually a trap — too hard to recover from, too easy to develop top-end fitness. Polarised volume produces both aerobic base and threshold power.

ASEAN heat + heart rate

Cardiovascular drift in tropical climates: at the same running pace, ASEAN-based athletes\' HR runs 5-15 bpm higher than temperate climates. Either: (a) slow down to keep HR in target zone, or (b) accept higher HR at given pace as heat acclimation cost. Heat acclimation takes 10-14 days of consistent training in heat to develop. Singapore + KL + Bangkok endurance athletes commonly train in 30°C 80% humidity — substantial HR adaptation required vs identical training in 18°C / dry.

10 Things to Know About HR Zones

Karvonen 1957 introduced HRR method. Modern wearables default to it.

HRR = Max HR − Resting HR. Wider HRR = more zone resolution.

5 zones: recovery, aerobic base, tempo, threshold, VO2 max.

Polarised training (Seiler 2010): 80% Z1-2, 20% Z4-5. Replaces threshold-dominant models.

RHR is a key fitness indicator: elite endurance athletes 35-50, recreational 50-65, untrained 60-80.

RHR drops with fitness over 6-12 weeks of consistent aerobic training. Track it as a progress marker.

Heat raises HR 5-15 bpm at the same pace. ASEAN-based athletes need to acclimate.

Sleep + stress affect HR. Bad sleep can elevate RHR 5-15 bpm; train accordingly.

Zone 2 fat oxidation peaks around the upper end of Z2 (~70% HRR). Below = too easy; above = carbs dominate.

"Talk test" cross-check: Z2 = full sentences possible. Z3 = phrases. Z4-5 = single words gasped.

Frequently asked questions

First thing in the morning, lying still for 1-2 minutes before getting up. Use a fitness tracker, smartwatch, or count pulse at wrist/neck for 60 seconds. Repeat 3-5 mornings and average. Trackers (Apple Watch, Whoop, Oura, Garmin) automate this with sleep RHR data.
Karvonen HRR is more accurate when you have a reliable RHR — accounts for individual aerobic baseline. % max HR alone is simpler but gives different zone widths. Modern wearables default to Karvonen. For competitive athletes targeting precise zones, Karvonen is the standard.
Zone 2 builds mitochondrial density and fat oxidation capacity — the foundation of endurance. Elite endurance athletes spend 70-80% of training there. Recreational runners often spend too much time in Zone 3, which fatigues without optimally adapting top or bottom.
Three possibilities. (1) Your tested max HR is higher than Tanaka prediction — use the override field. (2) You\'re training in heat — adjust pace down. (3) RHR is higher than entered — re-measure. Also: chronic fatigue, dehydration, illness all elevate HR. Use perceived exertion as a cross-check.
Modern endurance training model (Stephen Seiler, 2010): ~80% of weekly volume in Zones 1-2 (easy aerobic base), ~20% in Zones 4-5 (threshold + VO2 max work), minimal Zone 3. Used by elite cross-country skiers, marathon runners, cyclists, triathletes. Builds both aerobic base and top-end power efficiently.
Poor sleep elevates RHR 5-15 bpm + reduces HRV. Same effort feels harder + reaches target zones at slower paces. Use HRV trends + morning RHR to gauge readiness; on poor-sleep days, reduce intensity or substitute Zone 2 work for Zone 4 intervals.
Both. Talk test is rough but immune to monitor errors + heat/sleep variability: Z2 = full sentences, Z3 = phrases, Z4-5 = single words gasped. Use as cross-check vs HR data. If your monitor says Zone 2 but you can barely speak, you\'re actually in Zone 3-4.
No. All inputs stay in your browser.
Yes, slightly. Cycling HR at same intensity runs ~5-10 bpm lower than running (less muscle mass recruited). Some athletes use separate sport-specific max HR + zones. For most recreational use, the same zones work for both.
Karvonen 1957 paper. Seiler 2010 polarised training research. Joe Friel\'s "The Triathlete\'s Training Bible". Iñigo San Millán + Peter Attia podcasts on Zone 2.