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
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.