Zone 4 & Zone 5 Heart Rate Calculator
Find your Zone 4 and Zone 5 heart rate, and see how the two high-intensity zones differ.
What is Zone 4 heart rate?
In the five-zone framework used on this page, Zone 4 is 80–90% of maximum heart rate — a hard, high-intensity zone.[1] Zone 4 may overlap with threshold intensity for some athletes, but a percentage of max HR and an individually measured lactate threshold heart rate (LTHR) are different ways of defining intensity.
What is Zone 5 heart rate?
In the same framework, Zone 5 is 90–100% of maximum heart rate — the highest heart-rate zone.[1] It is commonly used for very hard intervals, but Zone 5 heart rate is not the same thing as VO₂max, and a watch showing Zone 5 does not prove you are at VO₂max.
Worked example
A 30-year-old man has an estimated max HR of 187 bpm (Tanaka). Zone 4 is about 150–168 bpm and Zone 5 about 168–187 bpm. For a 40-year-old man (180 bpm): Zone 4 144–162, Zone 5 162–180 bpm. For a 40-year-old woman (171 bpm, Gulati): Zone 4 137–154, Zone 5 154–171 bpm.
Zone systems vary between methods and platforms — some devices and coaches use different boundaries, reserve-based percentages, or threshold-based zones. Age-based max HR is only an estimate; see max heart rate formulas.
Your Zone 4 & Zone 5 Heart Rate
Zone 4 · Zone 5
How the calculator works
Without a resting heart rate: Zone 4 = 80–90% and Zone 5 = 90–100% of estimated max HR (Tanaka for men, Gulati for women). With a resting heart rate it switches to the Karvonen method: resting HR + percentage × (max HR − resting HR). The active method is shown above your results.
Disclaimer: This calculator is for informational purposes only and does not provide medical advice. Always consult with a healthcare professional before starting any new exercise program.
Zone 4 vs Zone 5
| Zone 4 | Zone 5 | |
|---|---|---|
| % of max HR (this page) | 80–90% | 90–100% |
| Relative intensity | Hard | Maximum / near-maximal |
| Typical use | Longer hard intervals and sustained hard efforts | Short, very hard intervals |
| Interval character | Longer repeats with shorter recoveries | Shorter repeats; harder to sustain, usually more recovery |
| Relationship to threshold | May overlap threshold intensity for some people — not the same as measured LTHR | Above threshold intensity for most people |
| Relationship to VO₂max | Not a VO₂max measure | Often used for VO₂max-oriented intervals — but Zone 5 ≠ VO₂max |
| Heart-rate limitation | HR can lag at the start of each interval | HR lag matters most: short efforts may end before HR reaches Zone 5 |
% of max HR (this page)
Zone 4: 80–90%
Zone 5: 90–100%
Relative intensity
Zone 4: Hard
Zone 5: Maximum / near-maximal
Typical use
Zone 4: Longer hard intervals and sustained hard efforts
Zone 5: Short, very hard intervals
Interval character
Zone 4: Longer repeats with shorter recoveries
Zone 5: Shorter repeats; harder to sustain, usually more recovery
Relationship to threshold
Zone 4: May overlap threshold intensity for some people — not the same as measured LTHR
Zone 5: Above threshold intensity for most people
Relationship to VO₂max
Zone 4: Not a VO₂max measure
Zone 5: Often used for VO₂max-oriented intervals — but Zone 5 ≠ VO₂max
Heart-rate limitation
Zone 4: HR can lag at the start of each interval
Zone 5: HR lag matters most: short efforts may end before HR reaches Zone 5
Zone 4, threshold and LTHR are not the same thing
This page uses a percentage-of-max-HR five-zone framework. Lactate threshold is a physiological point measured in a lab or field test, and LTHR is the heart rate at that point. Threshold intensity can fall inside Zone 4 for some people, but not for everyone. Our 80/20 calculator uses LTHR and a different seven-zone system — keep the two systems separate. To get an LTHR estimate, use the LTHR field-test calculator.
Zone 5 and VO₂max are not synonyms
VO₂max is your maximal oxygen uptake, measured with gas analysis. Zone 5 is a heart-rate range. Very hard intervals that reach Zone 5 can be relevant to VO₂max-oriented training, but entering Zone 5 does not mean VO₂max has been reached.
Heart rate lags during short, hard intervals
Heart rate does not change instantly with work intensity.[4] In practice:
- A short hard effort can start well before your heart rate reaches the target zone.
- Heart rate can stay high after the work intensity drops, into the recovery period.
- So during short intervals, heart rate alone is a lagging guide — effort, pace or power often react faster.
- Wearable time-in-zone is useful, but should not be read as exact time spent in a specific physiological state.
Why your watch may show a long time in Zone 5
If a device reports, say, 30 minutes in Zone 5, that can reflect how your max HR and zones were configured, individual differences in heart rate, heart rate staying elevated after hard efforts, or the device using a different zone framework. It is not automatically wrong — and it is not the same as exercising at VO₂max for that whole time. If your zones are based on an age estimate, checking the max HR your device uses is a good first step.
The 4 × 4 interval example
A well-studied session is 4 × 4 minutes at roughly 85–95% of max HR with easy recovery between intervals — spanning the top of Zone 4 and the lower part of Zone 5, so it does not belong to Zone 5 alone. In one study, 4 × 4 minutes at 90–95% HRmax improved VO₂max more than moderate training in the participants tested.[2] That result applies to that protocol and group; it is not a guarantee for every athlete.
A separate study of the 4 × 4 protocol found participants spent about 12.9 of 16 work minutes between 85 and 95% HRmax, with less time in range during the first interval than the later ones.[3] That is heart-rate lag in action: you should not expect to hit the target the moment each interval starts.
What Zone 4 and Zone 5 work is used for
The zones describe intensity, not guaranteed outcomes. Zone 4 work is typically used to practice sustaining hard efforts; Zone 5 work to train near-maximal efforts. Specific interval studies — like the 4 × 4 research above — have shown improvements in the groups tested, but those findings cannot be generalized into promises about any one person.
How long, and how much?
Zone 4 efforts tend to be longer intervals than Zone 5 efforts. Zone 5 efforts are generally shorter because near-maximal intensity is much harder to sustain. How much high-intensity training suits you depends on your fitness, goals, total training load and recovery — there is no universal weekly number. Many endurance plans keep most training easy; the 80/20 method is one example of a training-distribution approach.
Running and cycling
The same Zone 4 and Zone 5 concepts apply to running and cycling, but measured heart rates can differ between sports, and an age-estimated max HR is only an estimate. See running heart rate zones and cycling heart rate zones.
Frequently Asked Questions
What is Zone 4 heart rate?
In the five-zone framework used on this page, Zone 4 is 80–90% of maximum heart rate — a hard, high-intensity zone. For a 30-year-old man with an estimated max HR of 187 bpm (Tanaka), that is about 150–168 bpm. Other zone systems use different boundaries.
What is Zone 5 heart rate?
In the same framework, Zone 5 is 90–100% of maximum heart rate — the highest heart-rate zone. For a 30-year-old man with an estimated max HR of 187 bpm, that is about 168–187 bpm.
What is the difference between Zone 4 and Zone 5?
Zone 4 (80–90% of max HR) covers hard efforts that can be held for longer intervals. Zone 5 (90–100% of max HR) covers near-maximal efforts, which are usually shorter because they are much harder to sustain.
Is Zone 4 the same as lactate threshold?
Not necessarily. Zone 4 on this page is a percentage of estimated max HR. Lactate threshold and lactate threshold heart rate (LTHR) are measured individually. For some people threshold intensity falls inside Zone 4, for others it does not.
Is Zone 5 the same as VO2max?
No. Zone 5 is a heart-rate range. VO2max is your maximal oxygen uptake, measured with gas analysis. Zone 5 is often used for very hard intervals that can be relevant to VO2max-oriented training, but being in Zone 5 does not show that you are at VO2max.
Why does my watch show so much time in Zone 5?
Long Zone 5 readings can reflect how your max HR and zones are configured on the device, individual differences in heart rate, heart rate staying high after the hardest part of an effort, or the device using a different zone framework. It is not automatically an error, and it does not mean you exercised at VO2max the whole time.
How do I calculate my Zone 4 and Zone 5 heart rate?
Multiply your max heart rate by 0.80 and 0.90 for Zone 4, and by 0.90 and 1.00 for Zone 5. If you add a resting heart rate, the calculator uses the Karvonen method instead: resting HR + (80–90% or 90–100%) × (max HR − resting HR).
Sources
- Polar Electro. Heart Rate Zones — Polar Loop user manual.
Supports: Five-zone percentage framework (Zone 4 = 80–90%, Zone 5 = 90–100% of HRmax). - Helgerud J, et al. Aerobic high-intensity intervals improve VO₂max more than moderate training. Med Sci Sports Exerc. 2007;39(4):665–671.
Supports: 4 × 4-minute intervals at 90–95% HRmax improved VO₂max more than moderate training in that study. - Acala JJ, Roche-Willis D, Astorino TA. Characterizing the heart rate response to the 4 × 4 interval exercise protocol. Int J Environ Res Public Health. 2020;17(14):5103.
Supports: 4 × 4 protocol at 85–95% HRmax: about 12.9 of 16 work minutes spent in that range, with less time in range during interval 1. - Buchheit M, Laursen PB. High-intensity interval training, solutions to the programming puzzle. Part I. Sports Med. 2013;43(5):313–338.
Supports: Heart rate responds with a delay relative to work intensity during high-intensity intervals.