How do I calculate my maximum heart rate?

The traditional 220-minus-age formula is widely used but has a standard deviation of 10–12 beats, so many people are 20 or more off. The Tanaka equation, 208 − (0.7 × age), fits better across the age range. For a 40-year-old both give 180; for a 25-year-old they differ by 4.5 beats and for a 65-year-old by 7.5. Measuring beats predicting.

What is the difference between Karvonen and percentage of max?

Karvonen uses heart rate reserve — maximum minus resting — so it accounts for fitness. For a 40-year-old with a resting rate of 55, zone 2 is 108–126 by percentage of max but 130–142 by Karvonen. That is a 20+ beat gap, so always state which method a zone came from.

Which zone should I train in?

Most of the time, zone 2. Elite endurance athletes spend roughly 80% of their training in zones 1–2 and reserve genuinely hard work for the rest. The common recreational error is clustering in zone 3 — too hard to recover from, not hard enough to drive peak adaptation.

Why is zone 2 so slow?

Because it is meant to be. True zone 2 lets you speak in full sentences, which for many people means a pace that feels almost embarrassingly easy. The discomfort of going that slowly is exactly why people drift into zone 3 and compromise both their recovery and their hard sessions.

Are cycling and running zones the same?

No. Maximum heart rate in cycling typically sits 5–10 beats below running for the same person, largely because less muscle mass is engaged. Using running zones on the bike overstates the intensity you are actually achieving. Set them separately.

Why is my heart rate higher than usual at the same pace?

Heat, dehydration, caffeine, poor sleep, illness or accumulated training stress all raise heart rate at a given effort — a phenomenon sometimes called cardiac drift when it happens within a session. It usually means back off rather than push, particularly if it persists across days.

Heart Rate Zone Calculator (2025)

Calculate your 5 heart rate training zones for optimal fat burning, endurance, and performance. Uses both Max HR% and Karvonen (HRR) methods.

Age

Est. Max HR: 185 bpm

Resting Heart Rate (bpm)

Method

Zone 1 — Recovery125–137 bpm

Very light. Warm-up, cool-down, active recovery. (50–60% max HR)

Zone 2 — Aerobic Base137–149 bpm

Fat burning zone. Conversational pace. Build endurance. (60–70% max HR)

Zone 3 — Aerobic Fitness149–161 bpm

Improved aerobic capacity. Moderate effort. (70–80% max HR)

Zone 4 — Lactate Threshold161–173 bpm

Hard effort. Race pace. Increases lactate threshold. (80–90% max HR)

Zone 5 — Max Effort173–185 bpm

Maximum effort. Short intervals only. (90–100% max HR)

Analysis & insights

Your estimated max heart rate is 185 bpm (220 minus your age of 35). Your resting HR of 65 bpm is within the healthy range for adults. For most training, spend the majority of time in Zone 2 (137-149 bpm) — that's where you build the aerobic engine that powers everything else.

Max HR: 185 bpm

Calculated using Heart Rate Reserve (Karvonen). Resting HR in the healthy range.

Risk & benchmark gauge

Current band

Healthy

Resting HR: 65 bpm

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AthleteHealthyAverageElevated

Industry benchmarks

Your max HR185 bpm
Your resting HR65 bpm
Healthy resting range60-80 bpm
Endurance athletes40-60 bpm
Zone 2 (fat burn)137-149 bpm
Zone 4 (threshold)161-173 bpm

Key insights

Zone 2 is where the magic happens

Most aerobic adaptation (mitochondrial density, fat oxidation, capillary growth) happens at Zone 2 — a conversational pace you could maintain for 60+ minutes. Most amateurs train too hard most of the time and miss this.

The 80/20 rule

Elite endurance athletes spend ~80% of training in Zone 2 and 20% in high-intensity (Zones 4-5). This polarized pattern outperforms moderate-intensity-everywhere ("gray zone") training.

HRR is more accurate than %MaxHR

The Karvonen formula (HRR) accounts for your resting HR, which varies wildly between individuals. Use it if you can measure your true resting HR (first thing in the morning).

Recommended actions(4)

Spend 80% of cardio in Zone 2

High priority

You should be able to hold a conversation, breathing steadily through your nose. If you're mouth-breathing, slow down.

Impact: Builds the aerobic base that all higher-intensity work depends on.

Add 1-2 high-intensity sessions per week

High priority

Short intervals (4x4 minutes at Zone 5 with 3-minute recovery) drive VO2 max improvements that Zone 2 alone won't.

Impact: Even 6-8 weeks of structured intervals can raise VO2 max by 5-10%.

Track resting HR weekly

Medium priority

Persistent elevation (>10 bpm above baseline) signals overreaching, illness, or poor sleep. Listen to it.

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This tool is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for advice specific to your situation.

What is Heart Rate Training Zones?

Heart rate zones divide your usable range into bands, each associated with a different training effect. The idea is sound and genuinely useful: it stops easy days from creeping too hard and gives hard days a target worth hitting.

The weak link is how maximum heart rate is estimated. The famous 220-minus-age formula was never derived from careful research — it emerged from a rough fit to scattered data in the 1970s and its authors later acknowledged it had no scientific pedigree. Its standard deviation is around 10–12 beats per minute, meaning a substantial share of people sit more than 20 beats from their predicted maximum.

That matters because every zone is a percentage of that number. If the maximum is wrong by 15 beats, every zone boundary is wrong too. The formula is a reasonable starting point and a poor finishing one.

The formula — how to calculate Heart Rate Training Zones

Max HR (Tanaka) = 208 − (0.7 × age) Max HR (traditional) = 220 − age %MaxHR method: Zone = Max HR × percentage Karvonen (HRR): Zone = Resting HR + (Max HR − Resting HR) × percentage

Heart rate reserve: = Max HR minus resting HR — the range you can actually work within
Karvonen: = accounts for fitness by using resting heart rate, giving more individualised zones

Karvonen and %MaxHR produce meaningfully different targets for the same person. Karvonen is generally preferred because a fit person with a low resting heart rate gets appropriately harder zones.

Step-by-step example

01A 40-year-old with a resting heart rate of 55.
02Traditional max: 220 − 40 = 180. Tanaka: 208 − (0.7 × 40) = 180. They agree here; they diverge at the extremes of age.
03Heart rate reserve: 180 − 55 = 125.
04Zone 2 (60–70%) by %MaxHR: 180 × 0.60 = 108 to 180 × 0.70 = 126 bpm.
05Zone 2 by Karvonen: 55 + (125 × 0.60) = 130 to 55 + (125 × 0.70) = 142.5 bpm.
06That is a 20+ beat difference for the same zone and the same person — which is why the method used has to be stated, not assumed.
07For a 25-year-old the two max formulas diverge: 220 − 25 = 195 versus 208 − 17.5 = 190.5. For a 65-year-old: 155 versus 162.5.

The five zones and what each is for

Training zones by intensity

Zone	% of max	Feels like	Develops
1 — Recovery	50–60%	Very easy, full conversation	Active recovery, warm-up
2 — Aerobic base	60–70%	Comfortable, can talk in sentences	Fat oxidation, endurance, capillary density
3 — Tempo	70–80%	Moderately hard, short sentences	Aerobic capacity, lactate clearance
4 — Threshold	80–90%	Hard, few words	Lactate threshold, race pace
5 — VO2 max	90–100%	Maximal, no speech	Peak aerobic power, short intervals

Zone boundaries differ between systems — some use three zones, some seven. Comparing a zone number between apps without checking the underlying percentages is meaningless.

Why most people train too hard on easy days

A consistent finding in endurance training is that recreational athletes cluster in zone 3 — too hard to recover from, not hard enough to drive peak adaptation. Elite endurance athletes typically spend around 80% of their training time in zones 1 and 2, reserving genuinely hard efforts for the remaining fifth.

The reason zone 2 feels unsatisfying is that it is meant to. It should feel almost too easy, at a pace where you could hold a conversation in full sentences. Many people find their true zone 2 requires slowing to a pace that feels embarrassing, and that discomfort is exactly why they drift upward.

The practical value of a zone calculator is mostly in enforcing that restraint. Hard days benefit from a target too, but the more common error by a wide margin is making easy days moderately hard.

The talk test beats the formula

If you can speak in full sentences you are in zone 2. Short phrases means zone 3–4. Single words or none means zone 5. This requires no estimate of maximum heart rate and is often more accurate than a calculated zone, because it responds to how you are actually performing today rather than to a population average.

Getting a real maximum

Any age formula is a population estimate. If zones matter to your training, measure rather than predict.

A supervised laboratory test is the reference standard. A practical field alternative is a hard progressive effort — after thorough warm-up, several minutes at increasing intensity finishing with an all-out effort, taking the highest reading observed. This is genuinely strenuous and is not appropriate without medical clearance if you have cardiovascular risk factors, are over 40 and untrained, or have been inactive for a long period.

Two other factors are worth knowing. Maximum heart rate is activity-specific — cycling maximums typically run around 5–10 beats below running maximums for the same person, so zones set from a running test overstate cycling intensity. And heart rate lags: it takes a minute or two to respond to a change in effort, which makes it unreliable for short intervals where the effort is over before the number catches up.

Key considerations

State which method you are using — Karvonen and %MaxHR give different zones for the same person.
Measure maximum heart rate rather than predicting it if zones genuinely matter to you.
Aim for roughly 80% of training in zones 1–2, not the middle.
Use the talk test as a cross-check; it responds to today rather than to an average.
Set separate zones for cycling and running — maximums differ by 5–10 beats.
Heart rate lags effort by a minute or more, so it is poor for short intervals.
Heat, dehydration, caffeine, illness and stress all raise heart rate at a given effort.
Get medical clearance before maximal testing if you have cardiovascular risk factors.

Common mistakes to avoid

Treating 220-minus-age as accurate when its standard deviation is 10–12 beats.
Comparing zone numbers between apps that define zones differently.
Spending most training time in zone 3 — too hard to recover, too easy to adapt.
Using running zones for cycling, which overstates the intensity.
Chasing a heart rate target during short intervals where the number lags the effort.
Assuming an elevated heart rate on a hot day means you are working harder than planned.

Frequently asked questions

Sources & references

Written and fact-checked by the CalcProLabs Editorial Team. Read our calculation methodology and editorial policy.

Last updated July 28, 2026