How to use (3 steps)
- Choose a method: quick %HRmax, Karvonen (HRR) if you know resting HR, or %LTHR if you train with threshold data.
- Enter HRmax directly or estimate from age. The default 5-zone model works for most people; open Advanced settings if you need 3-zone, 7-zone LTHR, or custom boundaries.
- Results update automatically. Use "Copy table" or "Copy URL" to share exactly what you see.
Targets are training guidelines, not medical advice. Stop if you feel unwell and consult a professional if needed.
Inputs
Enter or adjust values to see bpm ranges for each zone. Zone 2 is highlighted by default.
Boundaries are rounded to whole bpm, and each zone gets its own non-overlapping range.
| Zone | Percent range | Low (bpm) | High (bpm) | Purpose |
|---|
How it's calculated
- %HRmax: target = HRmax x %. Age formulas are estimates; a tested HRmax is best when available.
- Karvonen (HRR): HRR = HRmax - HRrest, target = HRrest + HRR x %. This often personalises Zones 1-2.
- %LTHR: target = LTHR x %. The optional 7-zone preset mirrors common threshold-based training.
- Rounding: boundaries are rounded (half-up by default). To avoid overlap, each zone ends at "next boundary - 1" unless you pick inclusive boundaries.
- Current HR is matched against the integer ranges shown. Use it during a workout to check which zone you are in.
Interpretation (with a worked example)
Heart rate zones are training guidelines. Your actual effort can shift with sleep, heat, hills, dehydration, altitude, caffeine, and stress. If you feel unwell, stop and consult a professional.
Example: Karvonen (HRR), default 5-zone model
Suppose HRmax = 190 bpm and resting HR = 60 bpm, so HRR = 190 − 60 = 130. In the default 5-zone model, Zone 2 is 60–70%. The Zone 2 range is:
- Lower: 60 + 130×0.60 ≈ 138 bpm
- Upper: 60 + 130×0.70 ≈ 151 bpm
Why different methods give different bpm
- %HRmax is quick (needs only HRmax) but can be less individual when resting HR varies.
- HRR (Karvonen) includes resting HR, which shifts zone ranges compared with %HRmax.
- %LTHR is useful when you have threshold data from a field test or lab test.
Common pitfalls
- Wrist optical sensors can lag during intervals. A chest strap is often more stable for zone training.
- Use a measured HRmax if you have one; age formulas are population averages.
- Medication (for example beta blockers) and some medical conditions can make zone targets less meaningful.
References
How to use this calculator effectively
This guide helps you use Heart Rate Zone Calculator in a repeatable way: define a baseline, change one variable at a time, and interpret outputs with explicit assumptions before you share or act on results.
How it works
The page applies deterministic logic to your inputs and shows rounded output for readability. Treat it as a comparison workflow: run one baseline case, adjust a single parameter, and measure both absolute and percentage deltas. If a result seems off, verify units, time basis, and sign conventions before drawing conclusions. This approach keeps your analysis reproducible across teammates and sessions.
When to use
Use this page when you need a fast estimate, a classroom check, or a practical what-if comparison. It works best for planning and prioritization steps where you need direction and magnitude quickly before investing in deeper modeling, manual spreadsheets, or formal external review.
Common mistakes to avoid
- Changing multiple parameters at once, which hides the true cause of output movement.
- Mixing units (percent vs decimal, monthly vs yearly, gross vs net) across scenarios.
- Comparing with another tool without aligning defaults, constants, and rounding rules.
- Using rounded display values as exact downstream inputs without re-checking precision.
Interpretation and worked example
Run a baseline scenario and keep that result visible. Next, modify one assumption to reflect your realistic alternative and compare direction plus size of change. If the direction matches your domain expectation and the size is plausible, your setup is usually coherent. If not, check hidden defaults, boundary conditions, and interpretation notes before deciding which scenario to adopt.
See also
FAQ
What is the difference between %HRmax and Karvonen (HRR)?
%HRmax uses only your maximum heart rate. Karvonen (HRR) also uses resting heart rate: target = HRrest + (HRmax - HRrest) x %. HRR can place Zone 2 slightly lower for people with low resting HR.
How do I estimate HRmax?
If you do not have a lab test, pick an age formula such as 220 - age or 208 - 0.7*age (Tanaka). They are estimates only. If you have a measured HRmax from a hard effort, enter it directly.
Why do zone boundaries sometimes look close together?
All boundaries are rounded to whole bpm. Each zone ends at the next boundary minus one to avoid overlap, so adjacent numbers can be very close after rounding.
Is this medical advice?
No. This tool is informational. If you have heart issues, are pregnant, or feel unwell, consult a medical professional before training by heart rate.
What should I do first on this page?
Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.
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